Relays and Euro lights

McCoy, Charlie CMcCoy at
Tue Jun 4 13:25:37 EDT 2002


This is from a best practices site : (relevant part copied below)

Keep in mind I said to add micro balloons to the 5 minute epoxy.  5 minute
stuff is flexible, and allows for easy removal (the longer the cure, in
general, the stiffer the stuff).  I also said to add micro balloons to the
mix, which makes it even easier to remove.  Yes, you can get RTV (i.e.
silicone) that is non-damaging, but it must not have acetic acid.   In
regards to silver spoons and vinegar you might be right...And if I use a
relay design using silver spoons immersed in vinegar I'll keep your thoughts
in mind.  But I know from personal experience that acetic based RTV's do eat
electrical components, and apparently the University of Maryland, the
Department of the Navy, and the Department of Commerce also agree with me.
But then again, they probably recommend oil changes.



For equipment with neither hermetic sealing nor pressurization, protection
from fluid intrusion is achieved by the application of a polysulfide or an
RTV (Room Temperature Vulcanizing) sealant. Polysulfide is most resistant to
fluid attack, but one part noncorrosive RTV per MIL-A-46146 is easier to
apply and remove while still providing fairly good sealing of small areas.
Clear types of RTV allow visual inspection of the sealed surface; however,
they are not as resistant to temperature and operational fluids. Figure 5-2
is an example of a leaky equipment housing that was sealed by RTV, only to
have an operational fluid damage the RTV along the top cover-to-housing
mating surfaces. If an RTV has a vinegar odor-DO NOT APPLY IT TO AVIONIC
EQUIPMENT. This odor indicates the RTV is corrosive. Table 5-1 lists RTVs to
avoid (corrosive), as well as those known to be noncorrosive. Two part RTVs
generally are used in deep cure applications (potting and encapsulating).

-----Original Message-----
From: Bernie Benz [mailto:b.m.benz at]
Sent: Tuesday, June 04, 2002 2:08 PM
To: McCoy, Charlie
Cc: 200q20V mailing list
Subject: Re: Relays and Euro lights


Here is a little home grown experiment for you.  Put a silver spoon in a
glass of vinegar overnight and see what happens to it.  Absolutely nothing!
Epoxy is an OK sealant, but is not removeable.


> From: "McCoy, Charlie" <CMcCoy at>
> Date: Tue, 4 Jun 2002 07:06:53 -0700
> To: 200q20V mailing list <200q20v at>
> Subject: RE: Relays and Euro lights
> Don't use silicone caulk (see relay cover idea below) as it releases
> acid (i.e. vinegar) during the curing process and will cause corrosion on
> the contacts.  A 5 minute epoxy with micro-balloons (see your fav hobby
> store) is a better weather preventer.
> -----Original Message-----
> From: Bernie Benz [mailto:b.m.benz at]
> Sent: Tuesday, June 04, 2002 9:08 AM
> To: Chris Covington
> Cc: 200q20V mailing list
> Subject: Re: Relays and Euro lights
> Simple.  If I were unfortunate enough to live in Chicago, I'd put the
> package in a plastic bag, just like Audi does with the ECU to protect it
> from those that can't keep their drain holes clean.
> Bernie

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