[sdiy] D-70 red goo of death - polyurethane?

[cheater cheater]

I wonder if the guys who came up with RetroBright have anything to say
about this. To the layman yours truly it looks like their ballpark.

On Sun, Jan 27, 2013 at 1:02 PM, Robin Whittle <rw at firstpr.com.au> wrote:
> Hi David,
>
> My only guess is that the red material may have been a polyurethane
> compound, perhaps to glue the weights into the keys.  Polyurethanes can
> turn to crap of their own accord, relatively suddenly, after long
> periods of time.
>
> Spandex (Lycra) is a polyurethane material which is very stretchy - but
> in a particular garment it can all turn to stiff, brittle, stuff within
> some time period such as a year or so, when the garment is 10 or more
> years old.
>
> Clear, firm, self-adhesive "rubber" (not really) feet are made of
> polyurethane.  I had two in my van, on the remote (wired) volume and
> power control box for the sound system.  I affixed them in 1985.  Last
> year, both of them turned into a horrible sticky mess.  They were close
> together but not in a sealed environment, other than being inside the
> vehicle.  I don't know of any solvent which will touch it.  They were
> still firm enough to scrape off, but some residue remains for which
> there is no obvious method of dissolving.  While these clear
> self-adhesive feet are attractive, I think it is better to use real
> rubber feet with screws in the middle if you care about how the machine
> will be in its dotage.
>
> Most resilient foam, as used in seat cushions and for lining carry
> cases, road cases etc., is polyurethane foam.  I had some in a road case
> for a bass guitar and one year (it was at around 20 years old) it all
> turned into a horrible sticky mess - fortunately the guitar was not inside.
>
> I understand that this material can degrade and produce a byproduct of
> the degradation which itself catalyses the reaction.  I think this is a
> gas or a volatile liquid.  So if there is a particular kind of
> polyurethane in a sealed environment, it will all tend to go bad
> together.  I recall reading that higher temperatures and humidities are
> likely to facilitate this reaction.
>
> The only reference I have in my Bookmarks is is:
>
>   The degradation of polyester polyurethane: preliminary study of
>   1960s foam-laminated dresses
>
>   Doon Lovett and Dina Eastop    University of Southampton 2004
>
>
> http://www.iiconservation.org/archive/www.iiconservation.org/publications/pdffetch0a03.pdf?pub_id=139
>
> As far as I know, there's no degradation of "Estapol" and similar hard
> polyurethane sealants for wooden floors and the like.
>
>   - Robin
>