From: "Barry L. Ornitz" <ornitz@dpnet.net>
Subject: Re: FAQ on cosmetics posting WRONG !!! READ THIS ! ! ! ! ! !
Date: 02 Jun 1999
Newsgroups: rec.antiques.radio+phono

DBlakeart wrote in message
<19990602075026.05414.00000017@ng-co1.aol.com>...
>Ditto on the posting concerning accuracy. Nitrocellous lacquers
>were the norm in most low cost applacations from the 30's on due
>to thier sprayability.

Agreed.

>Also the info info on plastics restoration is toataily wrong.
>I'v contacted the FAQ poster befor, with no reaction.I've been
>restoring plastics professionly / full time for about 8 years.
>and YES THEY CAN BE REPAIRED AND RESTORED !   and  NO NO NO NO
>NO NO NO NO,and NO ,DO NOT USE ALCHOL OF ANY TYPE OR OTHER
>CHEMICALS ON PLASTIC BEFOR TESTING !!!!!!!!!!!!!!!!!!!!!


The basic information in the FAQ is excellent.  Pray tell how do you do the
testing...

>Celluolse type plastics are very sensitive and it is very easy
>to damage them. Sometimes even doing a small test spot can start
>a chemical reaction that can spread uncontrollably.

Speaking as someone who worked for 18 years in the research laboratories of
one of the world's largest manufacturers of cellulosic plastics (Eastman
Chemical), I see this as blatant BS.

Yes, cellulosic plastics are very sensitive to many solvents.  But the
solvents DO NOT start the degradation reactions.  The degradation begins
the day the cellulosic plastic is made.  There are residual acids present
including sulfuric, nitric for cellulose nitrate, acetic for cellulose
acetate, etc.  These acids are supposed to be washed out of the plastic
during its precipitation and neutralized.  But a little always remains.
Over time, this acid hydrolyses the cellulose "backbone" breaking the
polymer chain.  When this happens, the esterification acid is also released
which further promotes the degradation.  In a fairly short time, the
plastic can turn into a gooey mess.  Once the process gets started, there
is little you can do.

On the earliest sign of this, usually a slight acid smell (acrid, like
vinegar with the cellulose acetate), take the plastic and wash it in warm
water.  Then soak it overnight in a solution of baking soda.  Wash again
and dry thoroughly.  This will neutralize any surface acids and may prolong
the life of the item.  To minimize the future decomposition of cellulosics,
keep them dry but with air flow around them.  Museums have learned the hard
way that celluloid and other old plastics, kept under glass still
decompose.  The moving air tends to remove acid vapors that are formed, and
thus slows the reaction.

Using alcohol or other solvents on cellulosic plastics does NOT cause this
degradation.  However, since many solvents can soften or dissolve
cellulosics, you should be careful - typically using such as solvent as a
last choice.

>I think people assume that because a posting has a "FAQ" heading
>it must be right, well it's not neccesarly. In fact it may be
>dead wrong , and cause damage !!  I hope the poster of this info
>will concider the limits of his/or her knowage , and change or
>remove this section on cosmetics . Misinfomation helps no one.
>DAN @ OUTSIDER STUDIOS


I agree, and this is why I agree with the FAQ's.  I hope you follow your
own advice too.

There are no magic cleaning techniques for old radios that do an excellent
job with no work.  If the radio is worth restoring, it is worth the labor
to do things correctly.  This means "elbow grease" with soap and water
first.  If stronger measures are needed, use them carefully as these can
easily do damage if you are careless.  In all cases, testing a small,
inconspicuous area is a good way to start.

        73,  Barry L. Ornitz     WA4VZQ     ornitz@dpnet.net