Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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  #1   Report Post  
Q
 
Posts: n/a
Default Fibreglassing 101?

I need to make a couple of horns ( for audio use ) and have a couple of
questions as I never worked with this stuff before...

The local Home Depot clone ( in scandinavia ) sells the glass fibres,
polyester resin, hardener and gelcoat wich should be everything I need ?

The mold is made from a big chunk of MDF ( Medium Density Fibreboard ) that
I laminated from several smaller sheets, then cut the horn flare contour in
it on a lathe..

To give you an idea of what I am trying to do I put a picture of an existing
horn he http://www.naeslund.dk/peter/files/oprydning/hpt42.jpg The mold
I made fits inside the horn.. Note that the actual horn I am trying to make
is round, not rectangular like this..

Can anyone give me some idiot proof instructions on where to go from here,
before I waste 100$ worth of fibreglassing ingredients?

If not, heres a few questions:

How do I get the surface thats touching the mold as smooth as possible? (
The mold was turned on a lathe, so it is smooth, but I'd prefer the fancy
shiny surface :-)

How do I keep the fibreglass from sticking to the mold?

Any tips that may come in handy?

I know that this process involves nasty chemicals and nasty dust, so I will
be doing this outside wearing some sort of dust filtering mask..

Thanks in advance

/peter


  #2   Report Post  
wmbjk
 
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On Sun, 17 Jul 2005 00:44:34 +0200, "Q" wrote:

I need to make a couple of horns ( for audio use ) and have a couple of
questions as I never worked with this stuff before...

The local Home Depot clone ( in scandinavia ) sells the glass fibres,
polyester resin, hardener and gelcoat wich should be everything I need ?

The mold is made from a big chunk of MDF ( Medium Density Fibreboard ) that
I laminated from several smaller sheets, then cut the horn flare contour in
it on a lathe..

To give you an idea of what I am trying to do I put a picture of an existing
horn he http://www.naeslund.dk/peter/files/oprydning/hpt42.jpg The mold
I made fits inside the horn.. Note that the actual horn I am trying to make
is round, not rectangular like this..

Can anyone give me some idiot proof instructions on where to go from here,
before I waste 100$ worth of fibreglassing ingredients?

If not, heres a few questions:

How do I get the surface thats touching the mold as smooth as possible? (
The mold was turned on a lathe, so it is smooth, but I'd prefer the fancy
shiny surface :-)


That surface needs to be as non-porous as possible. Seal it with
whatever your fiberglass supplier has on hand and recommends. Furane
is one product, sprays easily, dries fast, sands readily, polishes
shiny, smells terrible. It's not very durable though.

How do I keep the fibreglass from sticking to the mold?


After sealing the surface, use a specialty type paste wax. Apply wax,
let dry as recommended (perhaps overnight), and buff. Do about 6
coats. Do not try to speed the process. You might also bake the mold
in a warm oven between coats to help get the wax to penetrate the
surface. For at least the first part, apply a couple of coats of PVA
(from the fiberglass supplier). Spray it on if you can, it won't brush
very well on a waxed surface.

Any tips that may come in handy?


I can't tell you how many times I've heard that folks making their
first piece don't get the mold sealed and waxed properly, and end up
with the mold and the part permanently bonded together. So you might
try sealing and waxing some samples first to test that your technique
is adequate. The first release on a new mold can be troublesome. Try
getting a little compressed air into one corner. If that doesn't work,
try getting some water into the released areas to dissolve the PVA.
After the first release, add another coat of wax. If the first part
was tough to release, you might use PVA on the second one as well. But
if the mold is properly prepped, all releases after the first one
should be easy. The tail on your horn doesn't appear to have much
taper, and the part is going to shrink around the mold. So expect the
part to have a good grip on your mold in that area. You might make the
first part a single layer thick. That will give you some layup
practice, and enable you to peel the part off the mold if it's stuck
in some areas.

Wayne
  #3   Report Post  
Franklin Newton
 
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"Q" wrote in message
...
I need to make a couple of horns ( for audio use ) and have a couple of
questions as I never worked with this stuff before...

The local Home Depot clone ( in scandinavia ) sells the glass fibres,
polyester resin, hardener and gelcoat wich should be everything I need ?

The mold is made from a big chunk of MDF ( Medium Density Fibreboard )

that
I laminated from several smaller sheets, then cut the horn flare contour

in
it on a lathe..

To give you an idea of what I am trying to do I put a picture of an

existing
horn he http://www.naeslund.dk/peter/files/oprydning/hpt42.jpg The

mold
I made fits inside the horn.. Note that the actual horn I am trying to

make
is round, not rectangular like this..

Can anyone give me some idiot proof instructions on where to go from here,
before I waste 100$ worth of fibreglassing ingredients?

If not, heres a few questions:

How do I get the surface thats touching the mold as smooth as possible? (
The mold was turned on a lathe, so it is smooth, but I'd prefer the fancy
shiny surface :-)

How do I keep the fibreglass from sticking to the mold?

Any tips that may come in handy?

I know that this process involves nasty chemicals and nasty dust, so I

will
be doing this outside wearing some sort of dust filtering mask..

Thanks in advance

/peter


1.Mold release to prevent the part sticking to the mold, one brand name is
Freekote, choose one that cures at room temp.
2. The gel coat goes on first, that's what makes the smooth surface.
3.Follow the directions for the resin system you have picked out, i.e. cure
times for the gel coat before bond coats and fabric, shouldn't have any
problems.
4. Do wear protective gear, you can build a reaction to the stuff over time,
so no bare hands.
5. Good luck!


  #4   Report Post  
Eide
 
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Default

Any local boat repair guys? Marinas? They'll show you just what you need.

"Q" wrote in message
...
I need to make a couple of horns ( for audio use ) and have a couple of
questions as I never worked with this stuff before...

The local Home Depot clone ( in scandinavia ) sells the glass fibres,
polyester resin, hardener and gelcoat wich should be everything I need ?

The mold is made from a big chunk of MDF ( Medium Density Fibreboard )
that
I laminated from several smaller sheets, then cut the horn flare contour
in
it on a lathe..

To give you an idea of what I am trying to do I put a picture of an
existing
horn he http://www.naeslund.dk/peter/files/oprydning/hpt42.jpg The
mold
I made fits inside the horn.. Note that the actual horn I am trying to
make
is round, not rectangular like this..

Can anyone give me some idiot proof instructions on where to go from here,
before I waste 100$ worth of fibreglassing ingredients?

If not, heres a few questions:

How do I get the surface thats touching the mold as smooth as possible? (
The mold was turned on a lathe, so it is smooth, but I'd prefer the fancy
shiny surface :-)

How do I keep the fibreglass from sticking to the mold?

Any tips that may come in handy?

I know that this process involves nasty chemicals and nasty dust, so I
will
be doing this outside wearing some sort of dust filtering mask..

Thanks in advance

/peter




  #5   Report Post  
Q
 
Posts: n/a
Default


"wmbjk" skrev i en meddelelse
...

That surface needs to be as non-porous as possible. Seal it with
whatever your fiberglass supplier has on hand and recommends. Furane
is one product, sprays easily, dries fast, sands readily, polishes
shiny, smells terrible. It's not very durable though.


The supplier is a local Home Depot clone w. highschool student employees, so
I doubt they have any recommandations :-)... They do have a boating supply
dept, wich is where I found the fibreglass stuff..

I found some silicon based mold release designed for Polyester resins at an
electronics supply place.. I just ordered a couple of cans..

How do I keep the fibreglass from sticking to the mold?


After sealing the surface, use a specialty type paste wax. Apply wax,
let dry as recommended (perhaps overnight), and buff. Do about 6
coats. Do not try to speed the process. You might also bake the mold
in a warm oven between coats to help get the wax to penetrate the
surface. For at least the first part, apply a couple of coats of PVA
(from the fiberglass supplier). Spray it on if you can, it won't brush
very well on a waxed surface.


Any clue if boatwax will work?

PVA is regular (white) wood glue ?... I could add a little destilled water
and spray it on

Someone mentioned using babypowder on the mold as a release.. Will that
work?

Any tips that may come in handy?


I can't tell you how many times I've heard that folks making their
first piece don't get the mold sealed and waxed properly, and end up
with the mold and the part permanently bonded together. So you might
try sealing and waxing some samples first to test that your technique
is adequate. The first release on a new mold can be troublesome. Try
getting a little compressed air into one corner. If that doesn't work,
try getting some water into the released areas to dissolve the PVA.
After the first release, add another coat of wax. If the first part
was tough to release, you might use PVA on the second one as well. But
if the mold is properly prepped, all releases after the first one
should be easy. The tail on your horn doesn't appear to have much
taper, and the part is going to shrink around the mold. So expect the
part to have a good grip on your mold in that area. You might make the
first part a single layer thick. That will give you some layup
practice, and enable you to peel the part off the mold if it's stuck
in some areas.


I could integrate a quickrelease fitting for the airhose in the mold, so I
can blow air between the mold and the piece..

I could do just a few layers on the mold, let it harden and add more layers
after I remove it from the mold... This would help the shrinking problem to
some degree, or am I way off track ?

Thanks for the input so far!

/peter




  #6   Report Post  
Q
 
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"Franklin Newton" skrev i en meddelelse
ink.net...


1.Mold release to prevent the part sticking to the mold, one brand name is
Freekote, choose one that cures at room temp.


I found some silicon based stuff.... If I start by applying a layer of
polyester on the mold, let it harden and spray it with the silicon based
stuff, will this be enough?

2. The gel coat goes on first, that's what makes the smooth surface.


AHA!... I learned something new today :-)

3.Follow the directions for the resin system you have picked out, i.e.

cure
times for the gel coat before bond coats and fabric, shouldn't have any
problems.


The directions are on the cans, so that wont be a problem..

4. Do wear protective gear, you can build a reaction to the stuff over

time,
so no bare hands.


Yup... have heard about some poor aircraft maintenance person who sprayed
his arm w. resin by accident.. The story says that the arm more or less
rotted in a few weeks... Besides local OSHA codes on the fibreglass industry
are mad here...I think you'd need less protective equipment to walk on the
moon :-)

5. Good luck!


Thanks, and thanks for the input..

/peter


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Q
 
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"Eide" skrev i en meddelelse
news:yyhCe.64565$R21.12623@lakeread06...
Any local boat repair guys? Marinas? They'll show you just what you need.


I have been looking around the area to see if I could bribe someone to do
these horns for me, but no luck so far.. Besides.. I might aswell play a
little with nasty chemicals :-)

/peter


  #8   Report Post  
Richard J Kinch
 
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Q writes:

How do I keep the fibreglass from sticking to the mold?


Silicone grease spread thinly, or petrolatum (Vaseline), or Rain-X.

This isn't that difficult. You don't fancy mold-release products.

You can also craft your mold out of that cheap pink polyester Bondo.
Unlike the MDF, you can add it as well as take it away.
  #9   Report Post  
Eide
 
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It's not that toxic, the Portuguese guys around here (RI) had been spreading
it with their bare hands until a few years ago. Don't get me wrong, most of
them aren't around anymore, and those that are have the shakes, but you
won't be rotting your arms off.

Yup... have heard about some poor aircraft maintenance person who sprayed
his arm w. resin by accident.. The story says that the arm more or less
rotted in a few weeks... Besides local OSHA codes on the fibreglass
industry
are mad here...I think you'd need less protective equipment to walk on the
moon :-)



  #10   Report Post  
Glenn Ashmore
 
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I have been making one off patterns molds and parts regularly for the boat
and can tell you what works for me but I don't know what would be available
where you are. Scandinavia is a big place. I think Denmark and Sweden have
some good sources for composite materials.

Mold finish: I sand to about 120 and spray on a polyester based tooling
primer called Duratec Surface primer. It is a soft high build polyester
primer. Wet sand from 400 to 1200 then an automotive compound and finally a
fine polish like McGuire's. Two coats of cake type carnauba based
automotive wax as a base for the mold release.

Mold release: PVA is polyvinyl alcohol. A green liquid that dries to a
thin water soluble film. Spray a very light coat as a binder coat. After
about 10 minutes it will be dry enough to spray a wet coat.

Glassing: To do a proper job you need several different glass fabrics and
the Home Despot is definitely not toe place to get them. Price is way to
high and you will be lucky to find anything outer than 6 oz plain weave
cloth.

Some terminology: "Gel Coat" is a thick surfacing polyester with lots of
solids. It is the surface that you see when you look at most fiberglass
boats. "Cloth" is a plain weave material. It comes in various weights from
..5 oz/sq yard to 8 oz. and is used to reinforce the surface. "Roving" is a
very heavy yarn woven into a loose fabric. It is used for strength and
mass. "Mat" is a random oriented fiberglass felt like material used to fill
the voids in the coarser roving and prevent the weave pattern from printing
through the gel coat. "Sanding Aid" is a liquid wax additive that is mixed
with the last coat of polyester resin. Polyester does not cure hard in the
presence of air. The wax migrates to the surface and forms a shielding
layer to keep air away from the curing resin.

Start with a sprayed on polyester gel coat as soon as the first coat has
flashed off spray on another. You can roll it on but be careful not to
damage the PVA release. Repeat until you have about 30 mills of thickness
and let is cure for an hour or so. Then you can roll on some regular
polyester resin and lay a scrim of 2oz cloth followed by a layer of 6 oz
cloth and a layer of 8oz mat. You want the resin to fully wet out
everything. Next come several layers alternating roving and mat to build
the thickness you need. Cover the last layer of mat with some 6 oz cloth
and seal it with resin with the wax additive..

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Q" wrote in message
...
I need to make a couple of horns ( for audio use ) and have a couple of
questions as I never worked with this stuff before...

The local Home Depot clone ( in scandinavia ) sells the glass fibres,
polyester resin, hardener and gelcoat wich should be everything I need ?

The mold is made from a big chunk of MDF ( Medium Density Fibreboard )
that
I laminated from several smaller sheets, then cut the horn flare contour
in
it on a lathe..

To give you an idea of what I am trying to do I put a picture of an
existing
horn he http://www.naeslund.dk/peter/files/oprydning/hpt42.jpg The
mold
I made fits inside the horn.. Note that the actual horn I am trying to
make
is round, not rectangular like this..

Can anyone give me some idiot proof instructions on where to go from here,
before I waste 100$ worth of fibreglassing ingredients?

If not, heres a few questions:

How do I get the surface thats touching the mold as smooth as possible? (
The mold was turned on a lathe, so it is smooth, but I'd prefer the fancy
shiny surface :-)

How do I keep the fibreglass from sticking to the mold?

Any tips that may come in handy?

I know that this process involves nasty chemicals and nasty dust, so I
will
be doing this outside wearing some sort of dust filtering mask..

Thanks in advance

/peter






  #11   Report Post  
Nick Müller
 
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Q wrote:

PVA is regular (white) wood glue ?


Yes, it is. But you should not take a water-resistant for obvious
reasons. :-))


Nick

--
Motormodelle / Engine Models:
http://www.motor-manufaktur.de
Ellwe 2FB * VTM 87 * DLM-S3a * cubic
more to come ...
  #12   Report Post  
Q
 
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"Glenn Ashmore" skrev i en meddelelse
news:xOlCe.171881$sy6.140027@lakeread04...
I have been making one off patterns molds and parts regularly for the boat
and can tell you what works for me but I don't know what would be

available
where you are. Scandinavia is a big place. I think Denmark and Sweden

have
some good sources for composite materials.


The main problem here seems to be limited availability simply because very
few people do stuff like this at home.. From the sound of the replies I
think I need to stop by one of the local yachtbuilders and see if they will
sell me the materials I need.. The Home Depot clone only has one grade of
cloth ( 300 grams per sq. meter ) and it aint cheap.... Altho: A common
wallpaper type here is woven glass cloth is dirt cheap.. Could I use the
Home Depot clone for the first layer ( the inner layer actually, but this is
the layer that would be visible ) and just use the wallpapergrade stuff for
a "filler" ? I dont need much strength, just need it to be relatively
stiff...

Mold finish: I sand to about 120 and spray on a polyester based tooling
primer called Duratec Surface primer. It is a soft high build polyester
primer. Wet sand from 400 to 1200 then an automotive compound and finally

a
fine polish like McGuire's. Two coats of cake type carnauba based
automotive wax as a base for the mold release.


Sounds reasonably simple... Although I'd need to replace the primer etc. for
something local...

Mold release: PVA is polyvinyl alcohol. A green liquid that dries to a
thin water soluble film. Spray a very light coat as a binder coat. After
about 10 minutes it will be dry enough to spray a wet coat.


Seems I am going to the yachtbuilder again :-)

Glassing: To do a proper job you need several different glass fabrics and
the Home Despot is definitely not toe place to get them. Price is way to
high and you will be lucky to find anything outer than 6 oz plain weave
cloth.


Seems I am going to the yachtbuilder again :-)


Some terminology: "Gel Coat" is a thick surfacing polyester with lots of
solids. It is the surface that you see when you look at most fiberglass
boats. "Cloth" is a plain weave material. It comes in various weights

from
.5 oz/sq yard to 8 oz. and is used to reinforce the surface. "Roving" is

a
very heavy yarn woven into a loose fabric. It is used for strength and
mass. "Mat" is a random oriented fiberglass felt like material used to

fill
the voids in the coarser roving and prevent the weave pattern from

printing
through the gel coat. "Sanding Aid" is a liquid wax additive that is

mixed
with the last coat of polyester resin. Polyester does not cure hard in

the
presence of air. The wax migrates to the surface and forms a shielding
layer to keep air away from the curing resin.


Excellent.. I needed some words here and there :-)

Start with a sprayed on polyester gel coat as soon as the first coat has
flashed off spray on another. You can roll it on but be careful not to
damage the PVA release. Repeat until you have about 30 mills of thickness
and let is cure for an hour or so. Then you can roll on some regular
polyester resin and lay a scrim of 2oz cloth followed by a layer of 6 oz
cloth and a layer of 8oz mat. You want the resin to fully wet out
everything. Next come several layers alternating roving and mat to build
the thickness you need. Cover the last layer of mat with some 6 oz cloth
and seal it with resin with the wax additive..


This was exactly what I was looking for, now I just need to source the
materials and try not to end up spending thousands of dollars in the process
:-)

/peter


  #13   Report Post  
Nick Müller
 
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Q wrote:

The main problem here seems to be limited availability


But you should have model builder shops (planes, ships) that sell that
stuff. At least per mail order. Or you get hints where to look for at
modelbuilders forums (yes, the colorful forums are evil for NewsGroups
users).

Nick
--
Motormodelle / Engine Models:
http://www.motor-manufaktur.de
Ellwe 2FB * VTM 87 * DLM-S3a * cubic
more to come ...
  #14   Report Post  
Q
 
Posts: n/a
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"Nick Müller" skrev i en meddelelse
...
Q wrote:

PVA is regular (white) wood glue ?


Yes, it is. But you should not take a water-resistant for obvious
reasons. :-))


Know of any online shops in Germany that sell the fibreglass materials?...
Am just north of you in Denmark, so it wouldnt be a huge problem getting the
stuff from Germany?

/peter


  #15   Report Post  
Q
 
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"Nick Müller" skrev i en meddelelse
...
Q wrote:

The main problem here seems to be limited availability


But you should have model builder shops (planes, ships) that sell that
stuff. At least per mail order. Or you get hints where to look for at
modelbuilders forums (yes, the colorful forums are evil for NewsGroups
users).



Most of the model builders I know either buy their stuff at the place I
mentioned or from Conrad in Germany.. Problem is the quantity... I need more
than a model boat would need but on the other hand I dont need a 55 gallon
drum of polyester :-)

I am going to Wacken near Hamburg in a few weeks ( www.wacken.com ) and
could stop in Hamburg if there are any good places to get the materials I
need?

/peter




  #16   Report Post  
Nick Müller
 
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Q wrote:

Know of any online shops in Germany that sell the fibreglass materials?...


Yep! Here you go (even in English): http://www.r-g.de/

Don't know wether they ship to Denmark, but I guess.
This company seems to be the best resource for that stuff. At least I've
seen it referenced many times in model builders NGs. I'm not in the
laminating.

HTH,
Niick
--
Motormodelle / Engine Models:
http://www.motor-manufaktur.de
Ellwe 2FB * VTM 87 * DLM-S3a * cubic
more to come ...
  #17   Report Post  
Nick Müller
 
Posts: n/a
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Q wrote:

Conrad in Germany..


Urgs! Not the best place. For anything. :-)


I am going to Wacken near Hamburg in a few weeks ( www.wacken.com ) and
could stop in Hamburg if there are any good places to get the materials I
need?


I'm from Munich, so I can't help you now. But I will post in
de.rec.modelle.misc to find a shop for you in Hamburg.

Stay tuned ...

Nick
--
Motormodelle / Engine Models:
http://www.motor-manufaktur.de
Ellwe 2FB * VTM 87 * DLM-S3a * cubic
more to come ...
  #18   Report Post  
Q
 
Posts: n/a
Default


"Nick Müller" skrev i en meddelelse
...
Q wrote:

Know of any online shops in Germany that sell the fibreglass

materials?...

Yep! Here you go (even in English): http://www.r-g.de/


This looks perfect.. I dont know about the prices, but compared to bribing a
yachtbuilder to do the hoens for me this would most likely be cheaper...

Don't know wether they ship to Denmark, but I guess.
This company seems to be the best resource for that stuff. At least I've
seen it referenced many times in model builders NGs. I'm not in the
laminating.


It seems that they do ship to DK.. Now I am just confused about the
quantities to order :-)..

/peter




  #19   Report Post  
patrick mitchel
 
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I'd also check for any radio control model airplane clubs or experimental
aircraft groups in your area as they might have several individuals that are
conversent on the composite subject. How bout kit car manufacturers? They
use glass bodies quite a bit. One thing I'm impressed with is the
willingness of the r.c.m guys to offer knowlegable suggestions on subjects
far from metal. Sometimes I think that rec.crafts...should be "materials"
instead of metal.. Regards Pat


  #20   Report Post  
Glenn Ashmore
 
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All the materials I mentioned are regularly used by all sorts of composite
workers. You should be able to find a distributor of FRP supplies somewhere
around any major coastal city or you can search the web for mail order
distributors Northern Europe. You might try Bang & Bonsomer in Finland or
Armatech in Sweden. They are distributors but can tell you who sells their
products retail. Or check with a local small boat designer for a source A
quick Google came up with http://www.thomassondesign.com/index.php . FRP
canoes use all the materials you will need.

In order from worst place to best places to buy composite supplies in the
quantity and types you need a

1) Model builder supply stores (Don't carry the heavier materials and they
specialize in small quantities so the price will be WAY to high.)
2) Big Box building Supply stores ( very limited choice and high prices)
3) Commercial boat builders - ( have everything you need but no way to sell
it to you. You have to rely on the sympathy factor)
4) Chandlers (boating supply store) (Usually can get anything you need but
at a price)
5) Mail order boat building supply companies (Set up to sell cut length
material and resins in liters)

As a wild guess I would think that an Electrovoice HPT42 horn would require
about 250 ml of gel coat, 2 meters of 2 and 6 oz cloth, 3-4 meters of mat
and roving and a little more than a liter of polyester. If your low end is
limited to 1300 Hz you can build it a lot lighter than a low end horn. If
you are working on a low end horn double or triple the roving and mat.

Either way be sure to roll out all the voids and consolidate the lay-up
really well. Any voids are going to add unwanted color. Ideally I would
vacuum bag the mat/roving lay-up. Keep the temperatures fairly low and cut
back some on the MEK (catalyst) to extend your working time long enough to
get the bag pulled before the resin kicks..

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Q" wrote in message
...

"Glenn Ashmore" skrev i en meddelelse
news:xOlCe.171881$sy6.140027@lakeread04...
I have been making one off patterns molds and parts regularly for the
boat
and can tell you what works for me but I don't know what would be

available
where you are. Scandinavia is a big place. I think Denmark and Sweden

have
some good sources for composite materials.


The main problem here seems to be limited availability simply because very
few people do stuff like this at home.. From the sound of the replies I
think I need to stop by one of the local yachtbuilders and see if they
will
sell me the materials I need.. The Home Depot clone only has one grade of
cloth ( 300 grams per sq. meter ) and it aint cheap.... Altho: A common
wallpaper type here is woven glass cloth is dirt cheap.. Could I use the
Home Depot clone for the first layer ( the inner layer actually, but this
is
the layer that would be visible ) and just use the wallpapergrade stuff
for
a "filler" ? I dont need much strength, just need it to be relatively
stiff...

Mold finish: I sand to about 120 and spray on a polyester based tooling
primer called Duratec Surface primer. It is a soft high build polyester
primer. Wet sand from 400 to 1200 then an automotive compound and
finally

a
fine polish like McGuire's. Two coats of cake type carnauba based
automotive wax as a base for the mold release.


Sounds reasonably simple... Although I'd need to replace the primer etc.
for
something local...

Mold release: PVA is polyvinyl alcohol. A green liquid that dries to a
thin water soluble film. Spray a very light coat as a binder coat.
After
about 10 minutes it will be dry enough to spray a wet coat.


Seems I am going to the yachtbuilder again :-)

Glassing: To do a proper job you need several different glass fabrics
and
the Home Despot is definitely not toe place to get them. Price is way to
high and you will be lucky to find anything outer than 6 oz plain weave
cloth.


Seems I am going to the yachtbuilder again :-)


Some terminology: "Gel Coat" is a thick surfacing polyester with lots of
solids. It is the surface that you see when you look at most fiberglass
boats. "Cloth" is a plain weave material. It comes in various weights

from
.5 oz/sq yard to 8 oz. and is used to reinforce the surface. "Roving"
is

a
very heavy yarn woven into a loose fabric. It is used for strength and
mass. "Mat" is a random oriented fiberglass felt like material used to

fill
the voids in the coarser roving and prevent the weave pattern from

printing
through the gel coat. "Sanding Aid" is a liquid wax additive that is

mixed
with the last coat of polyester resin. Polyester does not cure hard in

the
presence of air. The wax migrates to the surface and forms a shielding
layer to keep air away from the curing resin.


Excellent.. I needed some words here and there :-)

Start with a sprayed on polyester gel coat as soon as the first coat has
flashed off spray on another. You can roll it on but be careful not to
damage the PVA release. Repeat until you have about 30 mills of
thickness
and let is cure for an hour or so. Then you can roll on some regular
polyester resin and lay a scrim of 2oz cloth followed by a layer of 6 oz
cloth and a layer of 8oz mat. You want the resin to fully wet out
everything. Next come several layers alternating roving and mat to build
the thickness you need. Cover the last layer of mat with some 6 oz cloth
and seal it with resin with the wax additive..


This was exactly what I was looking for, now I just need to source the
materials and try not to end up spending thousands of dollars in the
process
:-)

/peter






  #21   Report Post  
Nick Müller
 
Posts: n/a
Default

Q wrote:

This looks perfect.. I dont know about the prices,


It just came to my mind, that R&G is filling the bottles for Conrad
(there's a fine print on Conrad's bottles). So you can guess who has the
better prices...


Now I am just confused about the quantities to order :-)..


Don't know. But there should be a rule of thump. Maybe 20% resin
compared to the fibre? You don't want to much resin, it just has to glue
the fibres together, 'cause the resin is weak compared to the fibres.
Some illuminated here will have a better answer.


I'm still waiting for tips for other suppliers (maybe in Hamburg)


Nick

--
Motormodelle / Engine Models:
http://www.motor-manufaktur.de
Ellwe 2FB * VTM 87 * DLM-S3a * cubic
more to come ...
  #22   Report Post  
Glenn Ashmore
 
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Default

Just checked out the R&G site. Looks like they have everything you need
except the tooling primer. Prices seem a little high but not outrageous.
That VAT really kills you guys.

Check out my post further down the thread for a SWAG on quantities. Always
best to order a bit extra. You can always find a use for it later.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Q" wrote in message
...

"Nick Müller" skrev i en meddelelse
...
Q wrote:

Know of any online shops in Germany that sell the fibreglass

materials?...

Yep! Here you go (even in English): http://www.r-g.de/


This looks perfect.. I dont know about the prices, but compared to bribing
a
yachtbuilder to do the hoens for me this would most likely be cheaper...

Don't know wether they ship to Denmark, but I guess.
This company seems to be the best resource for that stuff. At least I've
seen it referenced many times in model builders NGs. I'm not in the
laminating.


It seems that they do ship to DK.. Now I am just confused about the
quantities to order :-)..

/peter






  #23   Report Post  
Q
 
Posts: n/a
Default


"Glenn Ashmore" skrev i en meddelelse
news:5DsCe.171890$sy6.143080@lakeread04...
All the materials I mentioned are regularly used by all sorts of composite
workers. You should be able to find a distributor of FRP supplies

somewhere
around any major coastal city or you can search the web for mail order
distributors Northern Europe. You might try Bang & Bonsomer in Finland or
Armatech in Sweden. They are distributors but can tell you who sells

their
products retail. Or check with a local small boat designer for a source A
quick Google came up with http://www.thomassondesign.com/index.php . FRP
canoes use all the materials you will need.


Nick Müller pointed me towards www.r-g-composites.com and they seem to be
willing to ship to Denmark, although the resin seems to be cheaper at the
local home depot wannabe....

As a wild guess I would think that an Electrovoice HPT42 horn would

require
about 250 ml of gel coat, 2 meters of 2 and 6 oz cloth, 3-4 meters of mat
and roving and a little more than a liter of polyester. If your low end

is
limited to 1300 Hz you can build it a lot lighter than a low end horn. If
you are working on a low end horn double or triple the roving and mat.


These are approx. 4 times the size... So if I order:
10 lb bucket of resin
4 lbs of gelcoat
50 meters of mat ( http://tinyurl.com/aqe73 )
10 meters of cloth (http://tinyurl.com/bpbcy )
10 meters of cloth ( http://tinyurl.com/7mdyh )
+ an appropriate quantity of hardener and release for a pair

Incase you are curious ( you seem to know something about horns ):

The horn is a Tractrix type straight midrange horn for an 8" driver w. a
cutoff freq. at 300 Hz..

Either way be sure to roll out all the voids and consolidate the lay-up
really well. Any voids are going to add unwanted color. Ideally I would
vacuum bag the mat/roving lay-up. Keep the temperatures fairly low and cut
back some on the MEK (catalyst) to extend your working time long enough to
get the bag pulled before the resin kicks..


The vacuum is to drive the airbubbles out of the cast ? I have a couple of
vacuum pumps from scrapped vacuum bagging machines ( industrial models for
food products ) I might be able to make something usable from those..

Thanks for the guidance so far..

/peter


  #24   Report Post  
Nick Müller
 
Posts: n/a
Default

Glenn Ashmore wrote:

That VAT really kills you guys.


They will raise it next year here in Germany. The year after, government
will be bankrupt. :-(


Ni-****edoff-ck
--
Motormodelle / Engine Models:
http://www.motor-manufaktur.de
Ellwe 2FB * VTM 87 * DLM-S3a * cubic
more to come ...
  #25   Report Post  
Nick Müller
 
Posts: n/a
Default

Q wrote:

although the resin seems to be cheaper at the local home depot wannabe....


I wouldn't take that risk. You don't know how old the home dept's one
is, and you also can't select between different "pot time".


Just checked, they say R&G is good for fiberglas stuff.
.... and Wacken is good for music. :-)


Nick
--
Motormodelle / Engine Models:
http://www.motor-manufaktur.de
Ellwe 2FB * VTM 87 * DLM-S3a * cubic
more to come ...


  #26   Report Post  
Q
 
Posts: n/a
Default


"Nick Müller" skrev i en meddelelse
...
Glenn Ashmore wrote:

That VAT really kills you guys.


They will raise it next year here in Germany. The year after, government
will be bankrupt. :-(


You think its bad in Germany?..

Try 25% on everything, like here.. And no, its not lower on food like it is
on your side of the Border..

The fuel prices are rediculous too.. Diesel fuel costs about 5 US$ per
gallon here and the price keeps going up at a scary rate... I was thinking
of converting the van to run on plant oil, but unlike Germany, the plant oil
for automotive use is taxed like diesel here, so if you want the conversion
to pay off in an economical sense you need to cheat the tax people ( this is
relatively easy with the plant oil trick, but damned expensive if you get
caught )

Maybe its time to become a religious organisation and see about getting a
tax exempt like that amusement park in the US I heard about recently..

/peter


  #27   Report Post  
Q
 
Posts: n/a
Default


"Q" skrev i en meddelelse
...

Maybe its time to become a religious organisation and see about getting a
tax exempt like that amusement park in the US I heard about recently..


He
http://www.usatoday.com/travel/news/...k_x.htm?csp=34

/peter


  #28   Report Post  
wmbjk
 
Posts: n/a
Default

On Sun, 17 Jul 2005 02:38:04 +0200, "Q" wrote:


Any clue if boatwax will work?


There are lots of things that will work, but you'd need to do more
experimenting with them. The special purpose waxes aren't much more
expensive than car wax, floor wax, etc. But for two parts, you could
skip the wax altogether if you use a secure layer of PVA.

PVA is regular (white) wood glue ?... I could add a little destilled water
and spray it on


PolyVinyl Alcohol. A liter of it should be plenty for your project.
If you can't find a local place to buy proper supplies, just take some
empty bottles and a box of donuts to a local fiberglass shop.
Hopefully one that's used to building and prepping their own molds.

Someone mentioned using babypowder on the mold as a release.. Will that
work?


I can't imagine how. I'm guessing that you'll be brushing gelcoat onto
your prepped mold. Whatever's under your brush strokes can't be
disturbed.

This might be a good time to mention that gelcoat isn't really
necessary. You could brush on a layer of resin instead, let dry, then
start laminating. You'd probably get a bit more print-through, and
you'd have to paint the finished horns.

I could integrate a quickrelease fitting for the airhose in the mold, so I
can blow air between the mold and the piece.


That could help a lot in the worst case, but shouldn't be necessary if
you do the prep right. If the horn is going to have a long throat like
the one in the photo, then put any extra time into making that area
nice. As much taper as you can, straight and shiny surface, heavy PVA.

I could do just a few layers on the mold, let it harden and add more layers
after I remove it from the mold... This would help the shrinking problem to
some degree, or am I way off track ?


That might help a little, but you could be surprised how much a part
that isn't fully cured will distort if it's unsupported and you add
thick laminations. So long as the mold has been tested to make sure it
will release cleanly, I'd finish laminating the part while still on
the mold, and then let it cure for at least a day before releasing.

Glenn's advice was very good, it's obvious he has some experience. I
only disagreed on a couple of minor points - vacuum bagging, not worth
the trouble IMO for two relatively small parts. Ditto for roving. I'd
get some heavy mat (random strands bonded with a resin-soluble
binder). You can split it into thinner layers if you like. You can wet
it in place, but if it were me I'd lay the mat onto a flat, clean and
non-absorbent surface like Formica, wet it out fully and quickly, and
then pick up the slab of gooey glass and apply to the mold. As the
binder dissolves, the mat can be stretched to fit contours. So your
minimum shopping list could be: PVA, resin (promoted), catalyst, mat,
acetone, brushes and rollers. BTW, getting polyester resin on your
skin isn't anything to worry about. If it was I'd be dead by now. :-)
Washing your hands with acetone is *not* a good idea, although it's
done all the time.

FWIW, my shop once made an assortment of horns (a few dozen of each
size) much like the one in your photo. The largest was about 4 feet
tall. We used heavy gelcoat, one layer of chopped glass strand (from a
big machine), fitted Divinicell foam bonded over the flat areas, and
then more chopped glass over the whole thing.

Wayne
  #29   Report Post  
Glenn Ashmore
 
Posts: n/a
Default

" Maybe its time to become a religious organization and see about getting a
tax exempt like that amusement park in the US I heard about recently..


Just register as a boatbuilder. That is a non-profit organization if ever
there was one. :-)

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com



  #30   Report Post  
Q
 
Posts: n/a
Default


"wmbjk" skrev i en meddelelse
...
On Sun, 17 Jul 2005 02:38:04 +0200, "Q" wrote:


Any clue if boatwax will work?


There are lots of things that will work, but you'd need to do more
experimenting with them. The special purpose waxes aren't much more
expensive than car wax, floor wax, etc. But for two parts, you could
skip the wax altogether if you use a secure layer of PVA.


I found a source for it, so it wont be a problem..

PolyVinyl Alcohol. A liter of it should be plenty for your project.
If you can't find a local place to buy proper supplies, just take some
empty bottles and a box of donuts to a local fiberglass shop.
Hopefully one that's used to building and prepping their own molds.


Hmmmm... Donuts?... I am in Denmark.. The only place to get donuts is Mc
Donalds, but I get your point.... Over here stuff like that is usually
solved with a sixpack of beer :-)

This might be a good time to mention that gelcoat isn't really
necessary. You could brush on a layer of resin instead, let dry, then
start laminating. You'd probably get a bit more print-through, and
you'd have to paint the finished horns.


Gelcoat is available in smaller quantities, so that wont be a problem.. I
think the Gelcoat I can get locally is white though..

I could integrate a quickrelease fitting for the airhose in the mold, so

I
can blow air between the mold and the piece.


That could help a lot in the worst case, but shouldn't be necessary if
you do the prep right. If the horn is going to have a long throat like
the one in the photo, then put any extra time into making that area
nice. As much taper as you can, straight and shiny surface, heavy PVA.


It seems that my plan is to pain the mold with a couple layers of regular
turpentine based paint, wax it and coat with PVA...



Glenn's advice was very good, it's obvious he has some experience. I
only disagreed on a couple of minor points - vacuum bagging, not worth
the trouble IMO for two relatively small parts. Ditto for roving. I'd
get some heavy mat (random strands bonded with a resin-soluble
binder).


I like the idea of less things to go wrong or stick to the resin :-)

You can split it into thinner layers if you like. You can wet
it in place, but if it were me I'd lay the mat onto a flat, clean and
non-absorbent surface like Formica, wet it out fully and quickly, and
then pick up the slab of gooey glass and apply to the mold. As the
binder dissolves, the mat can be stretched to fit contours. So your
minimum shopping list could be: PVA, resin (promoted), catalyst, mat,
acetone, brushes and rollers.


Sounds what we used to do with wallpaperglue, chickenwire and old newspapers
in kindergarten :-)


BTW, getting polyester resin on your
skin isn't anything to worry about. If it was I'd be dead by now. :-)
Washing your hands with acetone is *not* a good idea, although it's
done all the time.


Hmmm.... I work in the food processing industry and the cleaning products
and desinfectants are hard on my hands as is.. Good thing about it is that I
can get "free" rubber gloves..

FWIW, my shop once made an assortment of horns (a few dozen of each
size) much like the one in your photo. The largest was about 4 feet
tall. We used heavy gelcoat, one layer of chopped glass strand (from a
big machine), fitted Divinicell foam bonded over the flat areas, and
then more chopped glass over the whole thing.


I decided to try this.. I usually make horns etc. from wood, but theres a
lot of work involved when you have to do everything by hand... Seeing that I
may end up having to make 40 more of these things the fibreglass seems like
a good solution..

/peter




  #31   Report Post  
Glenn Ashmore
 
Posts: n/a
Default


These are approx. 4 times the size... So if I order:
10 lb bucket of resin
4 lbs of gelcoat
50 meters of mat ( http://tinyurl.com/aqe73 )
10 meters of cloth (http://tinyurl.com/bpbcy )
10 meters of cloth ( http://tinyurl.com/7mdyh )
+ an appropriate quantity of hardener and release for a pair


I think you will need more resin than that. While a circular horn will not
resonate as much as a flat sided one you will still need a fair amount of
mass when your low end is around 300hz.. Look at product # 1901541 on page
7 of the fabrics. That is the roving I was talking about to build up the
mass and strength. You probably won't need as much of the woven cloth
because that only goes on the inner and outer layers.

You only need a little MEK-P catalyst as you use only 5 -10 ml per liter of
resin.

The vacuum is to drive the airbubbles out of the cast ? I have a couple
of
vacuum pumps from scrapped vacuum bagging machines ( industrial models for
food products ) I might be able to make something usable from those..


What the vacuum does is uniformly press the laminations against the mold
producing the densest possible layup. If you have the pump you can jerry
rig almost everything else but the process takes a bit of practice. You may
not want to risk it for your first time. Polyester sets up in 15 -30
minutes depending on the temperature, amount of MEK-P and the mass of the
layup so you don't have a lot of time to get the bag on. You can read some
basics of it on my web site in the Hull section.

If you want to try it get some 4 to 6 mil clear poly builders film for the
bag and seal it with vacuum tape. prod # 3901701 on page 2 of the vacuum
technology page. You will also need a breather mat prod# 3901801 on page.3
and a peel ply like 3901851. Alternately you can use nylon flag bunting or
taffeta for the peel ply. You can usually find that on the remnant counter
at a fabric store.


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com


  #32   Report Post  
Q
 
Posts: n/a
Default


"Glenn Ashmore" skrev i en meddelelse
newsCvCe.171910$sy6.164164@lakeread04...
" Maybe its time to become a religious organization and see about getting

a
tax exempt like that amusement park in the US I heard about recently..


Just register as a boatbuilder. That is a non-profit organization if ever
there was one. :-)


Yup... Seems that this project is going to cost a few boatbucks already :-)

Btw: I looked at your boat project page and I must say: DAMN, thats a big
project ! Wouldnt mind seeing some pics of the finished boat once you get
that far... Looks impressive..

Maybe you could enter the Tall Ships Race ( Formerly known as the Cutty Sark
Tall Ships Race ) and stop by here.. I took some pictures of some of the
ships that were racing here last year.. The most interesting ship was
probably the russian ship Sedov, built in 1921. The ship is made from steel
plates that are riveted, not welded. Theres a few pics of it he
http://www.naeslund.dk/peter/foto/tsr04/IMG_0046.JPG
http://www.naeslund.dk/peter/foto/tsr04/IMG_0050.JPG
More pics of some of the larger vessels here
http://www.naeslund.dk/peter/foto/tsr04/page_01.htm

Thanks again for your help... I will report back when I get my hands on the
resin etc.

/peter


  #33   Report Post  
Q
 
Posts: n/a
Default


"Nick Müller" skrev i en meddelelse
...

I wouldn't take that risk. You don't know how old the home dept's one
is, and you also can't select between different "pot time".


True...

Just checked, they say R&G is good for fiberglas stuff.


Excellent..

... and Wacken is good for music. :-)


I doubt it would be considered good for Schlager fans :-)

/peter


  #34   Report Post  
RoyJ
 
Posts: n/a
Default

Make sure that the gloves you get are immune to the resins in the
fiberglass. Gloves bonded to your hands is worse than washing in acetone.

Q wrote:

"wmbjk" skrev i en meddelelse
...

On Sun, 17 Jul 2005 02:38:04 +0200, "Q" wrote:



Any clue if boatwax will work?


There are lots of things that will work, but you'd need to do more
experimenting with them. The special purpose waxes aren't much more
expensive than car wax, floor wax, etc. But for two parts, you could
skip the wax altogether if you use a secure layer of PVA.



I found a source for it, so it wont be a problem..


PolyVinyl Alcohol. A liter of it should be plenty for your project.
If you can't find a local place to buy proper supplies, just take some
empty bottles and a box of donuts to a local fiberglass shop.
Hopefully one that's used to building and prepping their own molds.



Hmmmm... Donuts?... I am in Denmark.. The only place to get donuts is Mc
Donalds, but I get your point.... Over here stuff like that is usually
solved with a sixpack of beer :-)


This might be a good time to mention that gelcoat isn't really
necessary. You could brush on a layer of resin instead, let dry, then
start laminating. You'd probably get a bit more print-through, and
you'd have to paint the finished horns.



Gelcoat is available in smaller quantities, so that wont be a problem.. I
think the Gelcoat I can get locally is white though..


I could integrate a quickrelease fitting for the airhose in the mold, so


I

can blow air between the mold and the piece.


That could help a lot in the worst case, but shouldn't be necessary if
you do the prep right. If the horn is going to have a long throat like
the one in the photo, then put any extra time into making that area
nice. As much taper as you can, straight and shiny surface, heavy PVA.



It seems that my plan is to pain the mold with a couple layers of regular
turpentine based paint, wax it and coat with PVA...




Glenn's advice was very good, it's obvious he has some experience. I
only disagreed on a couple of minor points - vacuum bagging, not worth
the trouble IMO for two relatively small parts. Ditto for roving. I'd
get some heavy mat (random strands bonded with a resin-soluble
binder).



I like the idea of less things to go wrong or stick to the resin :-)


You can split it into thinner layers if you like. You can wet
it in place, but if it were me I'd lay the mat onto a flat, clean and
non-absorbent surface like Formica, wet it out fully and quickly, and
then pick up the slab of gooey glass and apply to the mold. As the
binder dissolves, the mat can be stretched to fit contours. So your
minimum shopping list could be: PVA, resin (promoted), catalyst, mat,
acetone, brushes and rollers.



Sounds what we used to do with wallpaperglue, chickenwire and old newspapers
in kindergarten :-)



BTW, getting polyester resin on your
skin isn't anything to worry about. If it was I'd be dead by now. :-)
Washing your hands with acetone is *not* a good idea, although it's
done all the time.



Hmmm.... I work in the food processing industry and the cleaning products
and desinfectants are hard on my hands as is.. Good thing about it is that I
can get "free" rubber gloves..


FWIW, my shop once made an assortment of horns (a few dozen of each
size) much like the one in your photo. The largest was about 4 feet
tall. We used heavy gelcoat, one layer of chopped glass strand (from a
big machine), fitted Divinicell foam bonded over the flat areas, and
then more chopped glass over the whole thing.



I decided to try this.. I usually make horns etc. from wood, but theres a
lot of work involved when you have to do everything by hand... Seeing that I
may end up having to make 40 more of these things the fibreglass seems like
a good solution..

/peter


  #35   Report Post  
Larry Jaques
 
Posts: n/a
Default

On Sun, 17 Jul 2005 17:40:53 +0200, the opaque "Q" clearly
wrote:

Maybe its time to become a religious organisation and see about getting a
tax exempt like that amusement park in the US I heard about recently..


He
http://www.usatoday.com/travel/news/...k_x.htm?csp=34


Bloody 'ell. When will the insanity stop? sigh

-
Gently-used Firestone tires for sale at discount!
-----------
http://diversify.com Website Application Programming


  #36   Report Post  
Q
 
Posts: n/a
Default


"RoyJ" skrev i en meddelelse
ink.net...
Make sure that the gloves you get are immune to the resins in the
fiberglass. Gloves bonded to your hands is worse than washing in acetone.


Hmmmm... Interesting idea.. Latex coated hands... Sounds kinky :-)

/peter


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