REFLECTOR: Epoxy and Hardener

Chuck Jensen cjensen at dts9000.com
Tue Sep 7 08:28:54 CDT 2004


John,

Seems like a fair request but its not easily answered, since the shelf life
of many of these materials are dependent on environmental factors such a
light exposure, temperature and humidity.  If the manufacturer makes the
"shelf-life" so short that they cover the worst case scenario, large volumes
of perfectly good epoxy will be thrown away.  On the other hand, if they
extend the shelf-life to reflect perfect storage conditions, some will
proceed using an epoxy that is marginal or worse.

We use tankers full of polymer epoxy for solidification of nuclear waste.
As part of our Process Control Program (PCP), we do test solidifications
with the neat (raw) binder materials.  If the observed behavior, such as
exotherm (if appropriate), cure time and cure state (dry and hard) is
acceptable, the epoxy and all of the hardners and diluents are then
considered to  also be acceptable.  You can do the same thing.  If the end
product is good, you can be assured that the ingredients are good.  If the
end product is garbage, one or more of the ingredients is garbage.  

Someone more experienced in structural epoxy use may correct me, but if the
cure and end product meets all the visual and physical checks, its can be
relied upon to be a good product.  In other words, the end product is
unlikely to have latent, hidden flaws due to bad ingredients resulting in a
sub-standard product, if all outward signs are acceptable.  No?

Chuck

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
Behalf Of John Dibble
Sent: Monday, September 06, 2004 10:17 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Epoxy and Hardener


With something as important as the long term structural integrity, I think
an iron
clad statement from the factory or the epoxy manufacturer concerning the
effect of age
on the epoxy ingredients is in order.

Jim Sower wrote:

> Can't imagine why not.  IIRC someone on the canard list checked with the
> factory and they said if you put the cap back on the jug it will be good
> forever.  If years per jug is an issue, I'd have to be a sloooooow
> builder.  Now if you was to put it in an open bucket and leave it out in
> the rain ...
> Let your conscience be your guide .... Jim S.
>
> Ronnie Brown wrote:
>
> >Jim,
> >
> >Does MGS have shelf life of greater than 1 years after opening?
> >
> >My EZ poxy hardener was fine for one year, then started getting dark,
then
> >like molasses.
> >
> >Ronnie
> >




_______________________________________________
To change your email address, visit
http://www.tvbf.org/mailman/listinfo/reflector

Visit the gallery!  www.tvbf.org/gallery
user:pw = tvbf:jamaicangoose
Check new archives: www.tvbf.org/pipermail
Check old archives: http://www.tvbf.org/archives/velocity/maillist.html


More information about the Reflector mailing list