Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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mike
 
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Default Deterioriating Foam in Instrument Cases?

Instrument cases often have foam to hold the stuff.
And it eventually turns to flakey, oily gunk.
Is there a prevention/remedy for this?
Will leaving the case open slightly materially affect
this degeneration?
Thanks, mike
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And it eventually turns to flakey, oily gunk.
Is there a prevention/remedy for this?


Ozone and heat accelerate the process. Some instruments by their very
design generate ozone and heat internally. Keeping the foam away from
direct sunlight certainly doesn't hurt, my experience is that sunlight
accelerates the process even more.

Best long-term strategy may be to remove the foam while it's intact,
before it deteriorates, and replace it. Especially if there's a fan to
distribute the little gunky particles around, cleaning up after the
fact is a real pain. This isn't always easy because often the foam is
glued in place (and the glue tends to go gooey and gunky itself.)

Tim.

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Mike Berger
 
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The remedy is to use much better foam. Polyurethane foam
isn't intended to last a long time.

mike wrote:
Instrument cases often have foam to hold the stuff.
And it eventually turns to flakey, oily gunk.
Is there a prevention/remedy for this?
Will leaving the case open slightly materially affect
this degeneration?
Thanks, mike

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GregS
 
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In article , Mike Berger wrote:
The remedy is to use much better foam. Polyurethane foam
isn't intended to last a long time.



I would say most intenders intend it to last. but have been
bitten including speaker companies. Better, as in
lasting longer? I have not really seen any other common soft pliable
foam.

greg

mike wrote:
Instrument cases often have foam to hold the stuff.
And it eventually turns to flakey, oily gunk.
Is there a prevention/remedy for this?
Will leaving the case open slightly materially affect
this degeneration?
Thanks, mike



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Jim Adney
 
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On Thu, 04 Aug 2005 23:30:33 -0700 mike wrote:

Instrument cases often have foam to hold the stuff.
And it eventually turns to flakey, oily gunk.
Is there a prevention/remedy for this?
Will leaving the case open slightly materially affect
this degeneration?


I doubt there is anything you can do about it. I'm sure that it is
just something that occurs with a particular kind of foam. I've seen
it in turntable mats and in instrument cases which hadn't been opened
in 20 years.

My only solution is to try to make a nice replacement from something
which I HOPE will last longer. So far, so good.

-
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Jim Adney
Madison, WI 53711 USA
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Michael A. Terrell
 
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wrote:

Ozone and heat accelerate the process. Some instruments by their very
design generate ozone and heat internally. Keeping the foam away from
direct sunlight certainly doesn't hurt, my experience is that sunlight
accelerates the process even more.

Best long-term strategy may be to remove the foam while it's intact,
before it deteriorates, and replace it. Especially if there's a fan to
distribute the little gunky particles around, cleaning up after the
fact is a real pain. This isn't always easy because often the foam is
glued in place (and the glue tends to go gooey and gunky itself.)

Tim.


Depending on the adhesive used either automotive hand cleaner, or
"Goo Gone" cleans up the mess. I scrapped a number of old Burroughs
computer systems in the past to use for storage. they were full of the
sticky residue.. I carefully lifted a corner and peeled away all that i
could which left the sticky film from the double sided mounting tape. I
laid the panels on a pair of saw horses out in the hot Florida sun and
rubbed a couple fingers full of cheap hand cleaner and let it sit for an
hour. I hosed it off, then removed the remaining bits of the double
sided tape and used a little more hand cleaner to finish it up. The
"Goo Gone" works on smaller areas, but it evaporates quickly so you may
have to use a lot of it.


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after threats were telephoned to my church.

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Jim Adney
 
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On Fri, 05 Aug 2005 22:49:42 -0700 mike wrote:

Jim Adney wrote:


My only solution is to try to make a nice replacement from something
which I HOPE will last longer. So far, so good.


What did you use that you hope will last longer?


I have just used stuff that I found with packing material, and that
SEEMED okay. This is totally unscientific. I've done this a couple of
times and so far, so good, but one of them may break down next year
and I won't have any better idea of what to do.

Sorry, but I really don't know what the stuff I used was. Not that it
would have mattered much, because I don't know what the bad stuff was.

I've got some samples from a foam company. I should call them and see
if they can offer any advise. I've used polyurethane foam in other
applications and that seems to be very stable and durable, but they
only had it in cream color. For the instruments I was repacking, I
wanted black.

The polyurethane foam went into a VW engine environment. It has held
up well with heat, oil, and fumes for about 15 years with no sign of
breaking down, so I would guess that if you could find polyurethane
that you liked, it would be a good bet.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------
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Mike Berger
 
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You used to be able to get latex based foam that would last a long
time. It wasn't as pliable as the polyurethane, so you'd have to
die-cut it.

GregS wrote:
In article , Mike Berger wrote:

The remedy is to use much better foam. Polyurethane foam
isn't intended to last a long time.




I would say most intenders intend it to last. but have been
bitten including speaker companies. Better, as in
lasting longer? I have not really seen any other common soft pliable
foam.

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none
 
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On Tue, 09 Aug 2005 13:43:29 -0400, (Fred McKenzie)
wrote:

In article ,
wrote:

Instrument cases often have foam to hold the stuff.
And it eventually turns to flakey, oily gunk.
Is there a prevention/remedy for this?


Mike-

This is a common problem with light traps in 35mm camera backs. In one I
had repaired, the foam was replaced by some kind of fiber/felt material.
It hasn't been many years, so it is hard to tell how long it will last.
The adhesive will probably fail before the material.

For instrument cases, some kind of cloth covering the padding material
might be helpful. One candidate for padding would be from a pillow. I
had a foam pillow that lasted for many years without turning to gunk.

Fred


Depends on the type of foam. Black or dark grey foam has more oils in
it hence the reason why it turns into a greasy, gunky mess when it
passes it's cure date.( oils are an essential part of the pigment.)
This is also the reason why white foams don't turn to gunk. They'll
just turn yellow/brown and eventually flake to dust.
You could esaily replace the old black foam with white foam and it'll
work just as well. Just be sure to get the same density for shock
protection value.
You could also cover the white with fabric, either felt or crush
vallour/velvet.
Cut your white foam to fit the case as well as the instrument that'll
be stored in the case.(I use a long smooth edge bread knife sharpened
to razor sharpness. Utility knives and exacto's will work as well.
Just bear in mind that foam is a synthetic that really dulls any edge
quickly. have plenty of spare replacement blades on hand.)
Applying a cloth cover is easy. Just spray the foam surfaces with a
spray adhesive like Super 77(3M) and press the fabric as smoothly as
possible into the cutout for the instrument, the going in a circular
pattern outward press the remaining cloth onto the outer "top" portion
of the foam. Trim the edges leaving about an inch or two to spare to
allow for "tuck in" between the foam's edge and the case walls.

Another good foam to use is the type used in marine applications for
boat seating and padding. It's a hard, closed cell white foam with a
smooth finish. Good for high shock applications. Can be gotten at most
boat or marine supply shops. Also has the advantage of having a very
long cure date.(will last for many years.)
When used in conjunction with less denser foam in a multi-layer
configuration provides the greatest shock protection.( an inch or two
of marine foam on the case walls and two or so of soft foam on top)


Black foam is used primarily for it's cosmetic value. After all to
most guys black foam just looks cooler in a shock case.
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