Hi

Any theatre / disco lighting experts out there ?
One of my new stained glass products is a lamp, with a wooden base,
and the 'shade' shaped like a 'Toblerone' bar standing on end.

Inside the shade is a compact fluorescent lamp (let's not have that
discussion again ! g) - and the shade consists of various pieces of
stained glass, fused glass, polished agate slabs etc...

The CF lamp is used because the finished lamp is not all that large,
and a conventional tungsten lamp would give out too much heat.

Only problem is - wih certain types of stained / art glass, it's
sometimes possible to see the outline of the lamp bulb, or of the
plastic body of the CF lamp - which detracts a little from the overall
effect.

So - bright idea time sigh!

How about using a piece of rolled up translucent material between the
CF lamp and the 'shade' - just to soften the outline of the bulb a
little....

I vaguely remember, from my college days running theatre / disco
lighting, that we had (?)acetate sheets called 'gels', that were used
in front of flood / spot lights. I see that these are still available
- I'm guessing that a 'neutral density' one is the way to go...

Alternatively, I see this item

http://tinyurl.com/yumtbu

...and wonder whether this would do the trick. Never seen it before -
has anybody used it and can tell me if it is as rigid as 'real' gel ?
Looks like it might just be 'fabric' - in which case it wouldn't stay
put inside the lamp.

Alternatively - does anybody have a suggestion for a
readily-available, durable, safe material that I could use instead ?

Many thanks in advance
Adrian

Adrian wrote:
snip

How about using a piece of rolled up translucent material between the
CF lamp and the 'shade' - just to soften the outline of the bulb a
little....

I vaguely remember, from my college days running theatre / disco
lighting, that we had (?)acetate sheets called 'gels', that were used
in front of flood / spot lights. I see that these are still available
- I'm guessing that a 'neutral density' one is the way to go...

Adrian,

As I recall (and it was a long time ago) the neutral density gel was to
allow the effective brightness to be reduced without using a dimmer (and
the consequent colour shifts of running lamps at different filament
temperatures) or any form of aperture control.

In a vaguely similar way, ND filters can be used photographically to
allow a larger aperture/longer exposure to be used when required. It
certainly does not act as a diffuser in this role!

The linked product looks to be appropriate (but I don't have the
experience to judge - just 'makes sense' level).

--
Rod

HI Rod

Thanks for the reply..

On Thu, 21 Feb 2008 08:39:52 +0000, Rod
wrote:

Adrian wrote:
snip

How about using a piece of rolled up translucent material between the
CF lamp and the 'shade' - just to soften the outline of the bulb a
little....

I vaguely remember, from my college days running theatre / disco
lighting, that we had (?)acetate sheets called 'gels', that were used
in front of flood / spot lights. I see that these are still available
- I'm guessing that a 'neutral density' one is the way to go...

Adrian,

As I recall (and it was a long time ago) the neutral density gel was to
allow the effective brightness to be reduced without using a dimmer (and
the consequent colour shifts of running lamps at different filament
temperatures) or any form of aperture control.

Ah - probably not one of those then g


In a vaguely similar way, ND filters can be used photographically to
allow a larger aperture/longer exposure to be used when required. It
certainly does not act as a diffuser in this role!

No - I suppose it wouldn't ......


The linked product looks to be appropriate (but I don't have the
experience to judge - just 'makes sense' level).

You're in the same boat as me then...
perhaps there's an expert about ?

Thanks
Adrian

"Adrian" wrote in message
...
HI Rod

Thanks for the reply..

On Thu, 21 Feb 2008 08:39:52 +0000, Rod
wrote:

Adrian wrote:
snip

How about using a piece of rolled up translucent material between the
CF lamp and the 'shade' - just to soften the outline of the bulb a
little....

I vaguely remember, from my college days running theatre / disco
lighting, that we had (?)acetate sheets called 'gels', that were used
in front of flood / spot lights. I see that these are still available
- I'm guessing that a 'neutral density' one is the way to go...

Adrian,

As I recall (and it was a long time ago) the neutral density gel was to
allow the effective brightness to be reduced without using a dimmer (and
the consequent colour shifts of running lamps at different filament
temperatures) or any form of aperture control.

Ah - probably not one of those then g


In a vaguely similar way, ND filters can be used photographically to
allow a larger aperture/longer exposure to be used when required. It
certainly does not act as a diffuser in this role!

No - I suppose it wouldn't ......


The linked product looks to be appropriate (but I don't have the
experience to judge - just 'makes sense' level).

You're in the same boat as me then...
perhaps there's an expert about ?

Thanks
Adrian

When I did stage lighting you could get various degrees of "Frost" gels

On Thu, 21 Feb 2008 08:30:48 +0000, Adrian
wrote:


Alternatively - does anybody have a suggestion for a
readily-available, durable, safe material that I could use instead ?

Use an acrylic tube of diameter suitable to fit over the lamp and
leave a bit of room for air circulation and cut to length so it covers
the bulb completely.

eg

http://www.westwardplastics.co.uk/sp...c_rod_tube.php

Depending upon quantities you intend to make either buy translucent
rather than clear tube or make it translucent by getting a cylinder
hone such as

http://www.shop-com.co.uk/Sealey_Cyl...l?sourceid=309

and running it up and down inside the tube until you get the desired
effect (Cylinder hones are flexible devices used on a normal electric
drill which have 3 abrasive pads designed to prepare the surfaces of
things like engine or brake cylinders -they produce a fine series of
scratches which if used in plastic tubes gives it a translucent
surface a bit like rubbing it with sandpaper).

On 21 Feb, 08:30, Adrian wrote:
Hi

Any theatre / disco lighting experts out there ?
One of my new stained glass products is a lamp, with a wooden base,
and the 'shade' shaped like a 'Toblerone' bar standing on end.

Inside the shade is a compact fluorescent lamp (let's not have that
discussion again ! g) - and the shade consists of various pieces of
stained glass, fused glass, polished agate slabs etc...

The CF lamp is used because the finished lamp is not all that large,
and a conventional tungsten lamp would give out too much heat.

Only problem is - wih certain types of stained / art glass, it's
sometimes possible to see the outline of the lamp bulb, or of the
plastic body of the CF lamp - which detracts a little from the overall
effect.

So - bright idea time sigh!

How about using a piece of rolled up translucent material between the
CF lamp and the 'shade' - just to soften the outline of the bulb a
little....

I vaguely remember, from my college days running theatre / disco
lighting, that we had (?)acetate sheets called 'gels', that were used
in front of flood / spot lights. I see that these are still available
- I'm guessing that a 'neutral density' one is the way to go...

Alternatively, I see this item

http://tinyurl.com/yumtbu

..and wonder whether this would do the trick. Never seen it before -
has anybody used it and can tell me if it is as rigid as 'real' gel ?
Looks like it might just be 'fabric' - in which case it wouldn't stay
put inside the lamp.

Alternatively - does anybody have a suggestion for a
readily-available, durable, safe material that I could use instead ?

Many thanks in advance
Adrian

Diffusion gels are available in quite a range, spun isn`t probably
what your looking for it softens the glare from big light sources at a
distance.Frost is a slightly smaller sledgehammer for same purpose.

To reverse the linear look , a Silk is possibly what you want, this,
clear, gel is brushed in one direction so might mitigate the vertical
linearity with a tube of horizontal orientated silk. In extreme cases
silk horizontal and vertical but lose a fair amount of light.

http://www.rosco.com/uk/filters/supergel.asp

http://www.leefilters.com

Look in yellow pages for local theatrical lighting trade counter,
they`ll stock one or both of the above 2 ranges, have flick through
their swatch books, gel isnt expensive.

HTH
Adam

Addendum

usenet sci.engr.lighting and rec.arts.theatre.stagecraft could do with
the traffic if you have similar questions :-)

On Thu, 21 Feb 2008 08:30:48 +0000, Adrian wrote:

Alternatively - does anybody have a suggestion for a
readily-available, durable, safe material that I could use instead ?

Fiberglass, as used in auto body repairs? Comes in woven and non-woven
(felt-like, mat, I forget the term...), it's heat resistant, and could be firmed
up with epoxy. too...


Thomas Prufer

HI Peter

Thanks for the reply

On Thu, 21 Feb 2008 10:10:42 +0000, Peter Parry
wrote:

On Thu, 21 Feb 2008 08:30:48 +0000, Adrian
wrote:


Alternatively - does anybody have a suggestion for a
readily-available, durable, safe material that I could use instead ?

Use an acrylic tube of diameter suitable to fit over the lamp and
leave a bit of room for air circulation and cut to length so it covers
the bulb completely.

That's a possibility.
Seems a bit 'overkill' though - and possibly tricky to transport in 2m
lengths (we live in the back of beyond out here in South-west
Ireland).

I was thinking that sheet gel might work out cheaper on the postage...

It's a possibility though - thanks

Adrian

HI Adam

Thanks for the reply

On Thu, 21 Feb 2008 03:31:47 -0800 (PST), Adam Aglionby
wrote:

On 21 Feb, 08:30, Adrian wrote:
Hi

Any theatre / disco lighting experts out there ?
One of my new stained glass products is a lamp, with a wooden base,
and the 'shade' shaped like a 'Toblerone' bar standing on end.

Inside the shade is a compact fluorescent lamp (let's not have that
discussion again ! g) - and the shade consists of various pieces of
stained glass, fused glass, polished agate slabs etc...

The CF lamp is used because the finished lamp is not all that large,
and a conventional tungsten lamp would give out too much heat.

Only problem is - wih certain types of stained / art glass, it's
sometimes possible to see the outline of the lamp bulb, or of the
plastic body of the CF lamp - which detracts a little from the overall
effect.

So - bright idea time sigh!

How about using a piece of rolled up translucent material between the
CF lamp and the 'shade' - just to soften the outline of the bulb a
little....

I vaguely remember, from my college days running theatre / disco
lighting, that we had (?)acetate sheets called 'gels', that were used
in front of flood / spot lights. I see that these are still available
- I'm guessing that a 'neutral density' one is the way to go...

Alternatively, I see this item

http://tinyurl.com/yumtbu

..and wonder whether this would do the trick. Never seen it before -
has anybody used it and can tell me if it is as rigid as 'real' gel ?
Looks like it might just be 'fabric' - in which case it wouldn't stay
put inside the lamp.

Alternatively - does anybody have a suggestion for a
readily-available, durable, safe material that I could use instead ?

Many thanks in advance
Adrian

Diffusion gels are available in quite a range, spun isn`t probably
what your looking for it softens the glare from big light sources at a
distance.Frost is a slightly smaller sledgehammer for same purpose.

To reverse the linear look , a Silk is possibly what you want, this,
clear, gel is brushed in one direction so might mitigate the vertical
linearity with a tube of horizontal orientated silk. In extreme cases
silk horizontal and vertical but lose a fair amount of light.

http://www.rosco.com/uk/filters/supergel.asp

http://www.leefilters.com

Thanks for the links - I've emailed both of the companies & we'll see
what results...

Thanks again
Adrian

HI Thomas

On Thu, 21 Feb 2008 14:11:45 +0100, Thomas Prufer
wrote:

On Thu, 21 Feb 2008 08:30:48 +0000, Adrian wrote:

Alternatively - does anybody have a suggestion for a
readily-available, durable, safe material that I could use instead ?

Fiberglass, as used in auto body repairs? Comes in woven and non-woven
(felt-like, mat, I forget the term...), it's heat resistant, and could be firmed
up with epoxy. too...


A possibility - but maybe a bit 'user-unfriendly' (if it's the stuff
I'm thinking of it sheds fibres rather easily)

I was hoping for something that I could just slip into position,
if you know what I mean !

Thanks
Adrian

On 21 Feb, 13:43, Adrian wrote:
HI Thomas

On Thu, 21 Feb 2008 14:11:45 +0100, Thomas Prufer

wrote:
On Thu, 21 Feb 2008 08:30:48 +0000, Adrian wrote:

Alternatively - does anybody have a suggestion for a
readily-available, durable, safe material that I could use instead ?

Fiberglass, as used in auto body repairs? Comes in woven and non-woven
(felt-like, mat, I forget the term...), it's heat resistant, and could be firmed
up with epoxy. too...

A possibility - but maybe a bit 'user-unfriendly' (if it's the stuff
I'm thinking of it sheds fibres rather easily)

I was hoping for something that I could just slip into position,
if you know what I mean !

Thanks
Adrian

Hi, I would go to www.stage-electrics.co.uk where you should get good
advice.
They should have all the diffusers and gels you need...the diffusers
come in different types
and densities...degrees of light reduction...or you could get clear
in different densities...
They are made to withstand very high heat so you could put them as
close to the bulb as you like
just staple into a tube as a test and drop it over...they handle
both rosco and lee.
I suppose you could glue into a tube shape for more permanent job.
They will give you a sample book of both makers so you can
experiment and choose.
I have some on hand which I would post if you like...not sure how
much or which ones...don't use them
anymore. You might have to buy a whole roll if you want the
diffuser....best to check first...the gels
they will do in smaller sheets, but, from memory, the diffusers
only come in rolls...ring to check first.
David G

In article ,
Adrian wrote:
I vaguely remember, from my college days running theatre / disco
lighting, that we had (?)acetate sheets called 'gels', that were used
in front of flood / spot lights. I see that these are still available
- I'm guessing that a 'neutral density' one is the way to go...

To soften a point source you use stuff called 'spun'. ND is used to reduce
intensity without altering colour temperature or on a light that can't be
dimmed.

--
*Beauty is in the eye of the beer holder...

Dave Plowman London SW
To e-mail, change noise into sound.

On Thu, 21 Feb 2008 13:26:36 +0000, Adrian
wrote:

I was thinking that sheet gel might work out cheaper on the postage...

Tracing paper - even cheaper (or baking paper - similar but
temperature resistant).

HI Peter

On Thu, 21 Feb 2008 22:58:49 +0000, Peter Parry
wrote:

On Thu, 21 Feb 2008 13:26:36 +0000, Adrian
wrote:

I was thinking that sheet gel might work out cheaper on the postage...

Tracing paper - even cheaper (or baking paper - similar but
temperature resistant).

Hmm - would it last, though ??

Adrian

Hi Dave

On Thu, 21 Feb 2008 22:17:30 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Adrian wrote:
I vaguely remember, from my college days running theatre / disco
lighting, that we had (?)acetate sheets called 'gels', that were used
in front of flood / spot lights. I see that these are still available
- I'm guessing that a 'neutral density' one is the way to go...

To soften a point source you use stuff called 'spun'. ND is used to reduce
intensity without altering colour temperature or on a light that can't be
dimmed.

Ah - OK
I got an email back from Lee Filters - they seem to think that I need

"a 129 Heavy Frost or 216 white diiffusion".

and then went on to comment

"216 transmits 36% light while the 129 is darker with a 25%
transmission".

But they've also given me a contact in Dublin who is both a stockist
and a 'user' of their products - so hopefully I can get some sheets of
various materials to play with and decide which one's best...

Many thanks
Adrian

On Fri, 22 Feb 2008 08:10:43 +0000, Adrian
wrote:

Hmm - would it last, though ??

Probably as well as a film, and much easier for the user to replace
if/when it gets damaged.

http://www.lakeland.co.uk/product.aspx/!5511_5510

It's a silicone coated paper stable up to 230deg C or so. Bakewell is
one commonly available brand name.

In article ,
Adrian wrote:
To soften a point source you use stuff called 'spun'. ND is used to
reduce intensity without altering colour temperature or on a light that
can't be dimmed.

Ah - OK I got an email back from Lee Filters - they seem to think that I
need

"a 129 Heavy Frost or 216 white diiffusion".

Yes - those would do but IMHO more likely to show through the glass as a
bit of a bodge. They are a form of thin sheet plastic. 'Spun' or 'silk'
could be made into a sort of bag which would look better.

and then went on to comment

"216 transmits 36% light while the 129 is darker with a 25%
transmission".

But they've also given me a contact in Dublin who is both a stockist
and a 'user' of their products - so hopefully I can get some sheets of
various materials to play with and decide which one's best...

Do you have location filming going on in your area? If so ask the sparks
for some offcuts. It's normally used in pretty large pieces to cover
windows etc so has a fair amount of wastage.

--
*A chicken crossing the road is poultry in motion.*

Dave Plowman London SW
To e-mail, change noise into sound.

Hi Dave

On Fri, 22 Feb 2008 18:23:00 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Adrian wrote:
To soften a point source you use stuff called 'spun'. ND is used to
reduce intensity without altering colour temperature or on a light that
can't be dimmed.

Ah - OK I got an email back from Lee Filters - they seem to think that I
need

"a 129 Heavy Frost or 216 white diiffusion".

Yes - those would do but IMHO more likely to show through the glass as a
bit of a bodge. They are a form of thin sheet plastic. 'Spun' or 'silk'
could be made into a sort of bag which would look better.

OK - understood.....
Would 'bagging' a CFL be a bad idea from the heat generation / unit
life point of view ?


and then went on to comment

"216 transmits 36% light while the 129 is darker with a 25%
transmission".

But they've also given me a contact in Dublin who is both a stockist
and a 'user' of their products - so hopefully I can get some sheets of
various materials to play with and decide which one's best...

Do you have location filming going on in your area?

Not that I know of.....
Not a lot of call for gloomy West Cork weather in filmed drama at the
moment - or so it seems g

If so ask the sparks
for some offcuts. It's normally used in pretty large pieces to cover
windows etc so has a fair amount of wastage.

I'll keep my eyes peeled....

Many thanks
Adrian

Adrian wrote:
Hi Dave
On Fri, 22 Feb 2008 18:23:00 +0000 (GMT), "Dave Plowman (News)"
wrote:
In article ,
Adrian wrote:

To soften a point source you use stuff called 'spun'. ND is used to
reduce intensity without altering colour temperature or on a light that
can't be dimmed.

Ah - OK I got an email back from Lee Filters - they seem to think that I
need

"a 129 Heavy Frost or 216 white diiffusion".

Yes - those would do but IMHO more likely to show through the glass as a
bit of a bodge. They are a form of thin sheet plastic. 'Spun' or 'silk'
could be made into a sort of bag which would look better.

OK - understood.....
Would 'bagging' a CFL be a bad idea from the heat generation / unit
life point of view ?


and then went on to comment

"216 transmits 36% light while the 129 is darker with a 25%
transmission".

But they've also given me a contact in Dublin who is both a stockist
and a 'user' of their products - so hopefully I can get some sheets of
various materials to play with and decide which one's best...

Do you have location filming going on in your area?

Not that I know of.....
Not a lot of call for gloomy West Cork weather in filmed drama at the
moment - or so it seems g

If so ask the sparks
for some offcuts. It's normally used in pretty large pieces to cover
windows etc so has a fair amount of wastage.

I'll keep my eyes peeled....

Many thanks
Adrian


Paper liners work well in terms of distributing the light, but even
thin ones reduce light throughput quite heavily.

Gels are unnecessarily expensive.

A plastic tube around the lamp would likely be unsafe if someone
installed a filament bulb. Also a best it could only enlarge the
visible light source to the size of the tube.

One most effective diffuser material is woven nylon cloth. This
effectively conceals the light source. It can be used as a shade
liner, and is then compatible with all lamp types. I dont know the
light transmission figure, but not far off 100%.


Would 'bagging' a CFL be a bad idea from the heat generation / unit
life point of view ?

Yes. It could also be dangerous if you combine this with normal end
user practices.


NT

On Feb 23, 1:24 pm, wrote:
Adrian wrote:
Hi Dave
On Fri, 22 Feb 2008 18:23:00 +0000 (GMT), "Dave Plowman (News)"
wrote:
In article ,
Adrian wrote:
To soften a point source you use stuff called 'spun'. ND is used to
reduce intensity without altering colour temperature or on a light that
can't be dimmed.

Ah - OK I got an email back from Lee Filters - they seem to think that I
need

"a 129 Heavy Frost or 216 white diiffusion".

Yes - those would do but IMHO more likely to show through the glass as a
bit of a bodge. They are a form of thin sheet plastic. 'Spun' or 'silk'
could be made into a sort of bag which would look better.

OK - understood.....
Would 'bagging' a CFL be a bad idea from the heat generation / unit
life point of view ?

and then went on to comment

"216 transmits 36% light while the 129 is darker with a 25%
transmission".

But they've also given me a contact in Dublin who is both a stockist
and a 'user' of their products - so hopefully I can get some sheets of
various materials to play with and decide which one's best...

Do you have location filming going on in your area?

Not that I know of.....
Not a lot of call for gloomy West Cork weather in filmed drama at the
moment - or so it seems g

If so ask the sparks
for some offcuts. It's normally used in pretty large pieces to cover
windows etc so has a fair amount of wastage.

I'll keep my eyes peeled....

Many thanks
Adrian

Paper liners work well in terms of distributing the light, but even
thin ones reduce light throughput quite heavily.

Its a diffuser but as you mention at an output cost

Gels are unnecessarily expensive.

Gel isn`t particularly expensive, but bnot sure if the OP is
considering this for a one off or is seeking something to use in a
production item.
Even production quantities get a lot of sleeves out of a sheet.

There is holographic and prismatic optical diffuser films made by
companies like 3M, generally used for things like display backlights,
these are expensive.


A plastic tube around the lamp would likely be unsafe if someone
installed a filament bulb. Also a best it could only enlarge the
visible light source to the size of the tube.

Gel is a self extigushing polycarbonate commonly used in front of 2kW
lamps, would rate it as safe even in direct contact with an 11W CFL.
Stapled it around linear fluro tubes for years.

One most effective diffuser material is woven nylon cloth. This
effectively conceals the light source. It can be used as a shade
liner, and is then compatible with all lamp types. I dont know the
light transmission figure, but not far off 100%.


Even ultra clear glass is around 95% transmission, would think woven
nylon cloth would be significantly below this.
Spun diffuser is usually glass fibre of some form, think 2kW is
probably a small light on a TV or film set.
Silks and frosts tend to be plastic films.

Would 'bagging' a CFL be a bad idea from the heat generation / unit
life point of view ?

Yes. It could also be dangerous if you combine this with normal end
user practices.

Sleeve would be preferable, trapping heat around CFL ballast bases
isn`t good for them.

Adam

NT

HI Adam

On Sat, 23 Feb 2008 08:15:11 -0800 (PST), Adam Aglionby
wrote:

On Feb 23, 1:24 pm, wrote:
Adrian wrote:
Hi Dave
On Fri, 22 Feb 2008 18:23:00 +0000 (GMT), "Dave Plowman (News)"
wrote:
In article ,
Adrian wrote:
To soften a point source you use stuff called 'spun'. ND is used to
reduce intensity without altering colour temperature or on a light that
can't be dimmed.

Ah - OK I got an email back from Lee Filters - they seem to think that I
need

"a 129 Heavy Frost or 216 white diiffusion".

Yes - those would do but IMHO more likely to show through the glass as a
bit of a bodge. They are a form of thin sheet plastic. 'Spun' or 'silk'
could be made into a sort of bag which would look better.

OK - understood.....
Would 'bagging' a CFL be a bad idea from the heat generation / unit
life point of view ?

and then went on to comment

"216 transmits 36% light while the 129 is darker with a 25%
transmission".

But they've also given me a contact in Dublin who is both a stockist
and a 'user' of their products - so hopefully I can get some sheets of
various materials to play with and decide which one's best...

Do you have location filming going on in your area?

Not that I know of.....
Not a lot of call for gloomy West Cork weather in filmed drama at the
moment - or so it seems g

If so ask the sparks
for some offcuts. It's normally used in pretty large pieces to cover
windows etc so has a fair amount of wastage.

I'll keep my eyes peeled....

Many thanks
Adrian

Paper liners work well in terms of distributing the light, but even
thin ones reduce light throughput quite heavily.

Its a diffuser but as you mention at an output cost

Gels are unnecessarily expensive.

Gel isn`t particularly expensive, but bnot sure if the OP is
considering this for a one off or is seeking something to use in a
production item.

Somewhere in-between g
I'd expect to sell maybe 20 of these lamps in a year - so it's sort of
'production' quantities.

Even production quantities get a lot of sleeves out of a sheet.

The lamps themselves are about 12" tall and each side of the lamp is
4" (it's 'Toblerone'-shaped). So I'd imagine (cba to do the maths on a
Saturday afternoon g) that one sheet of 12" x 12" gel would sit
quite comfortable inside the 'shade' of the lamp - and be held in
place by its own 'springyness' - this would also allow it to be as far
away as possible from the CFL bulb.

As each finished lamp is a one-off 'art' item, I think that the cost
of a sheet of gel can be 'absorbed' in the final selling price -
assuming that it's less than a fiver or so...


There is holographic and prismatic optical diffuser films made by
companies like 3M, generally used for things like display backlights,
these are expensive.


A plastic tube around the lamp would likely be unsafe if someone
installed a filament bulb. Also a best it could only enlarge the
visible light source to the size of the tube.

Gel is a self extigushing polycarbonate commonly used in front of 2kW
lamps, would rate it as safe even in direct contact with an 11W CFL.
Stapled it around linear fluro tubes for years.

One most effective diffuser material is woven nylon cloth. This
effectively conceals the light source. It can be used as a shade
liner, and is then compatible with all lamp types. I dont know the
light transmission figure, but not far off 100%.


Even ultra clear glass is around 95% transmission, would think woven
nylon cloth would be significantly below this.
Spun diffuser is usually glass fibre of some form, think 2kW is
probably a small light on a TV or film set.
Silks and frosts tend to be plastic films.

As mentioned above - I like the idea of a gel / film as it would tend
to be self-supporting.


Would 'bagging' a CFL be a bad idea from the heat generation / unit
life point of view ?

Yes. It could also be dangerous if you combine this with normal end
user practices.

Sleeve would be preferable, trapping heat around CFL ballast bases
isn`t good for them.

OK - just waiting on my local (Dublin!) distributor to get back to me
- maybe I'll have to call them on Monday

Thanks
Adrian