Andrew,
I read your post with interest as I have pondered the same question.
I bought my first kit in 1994. It was supplied with two cans of Redux,
one of which I opened and began using until the project ground to a halt
(like so many), the other remained sealed.
Long after the "use-by" date, I resumed construction and mindful of the
age of the Redux but curios as to how it degraded with time, I contacted
Ciba-Geigy and was lucky enough to be able to speak to one of their
research chemists.
Refreshingly honest, he assured me that both resin and hardener are
totally inert and very stable and that, in theory, it would not degrade
over time. When I asked why they advised a 36 month "use by" shelf-life,
he answered that as epoxies were relatively "modern", there was no
historical evidence of any degradation and that it was only added to
placate various regulating authorities.He did warn that the yellow resin
would most likely crystallize over time, but that chemically it was
unaltered and a gentle warming in a water bath would restore it to its
original liquid state (the opened can subsequently did, as predicted,
and was restored exactly as advised).
Returning to my two original cans, both had a use-by date of October
1998 -- I still have them and continue to use them today, 18 years after
manufacture. It works perfectly.
This also remains true of other epoxies. My SP Systems Ampreg 20 still
performs perfectly (expiry 1999) and my super-expensive Polyfibre
"Super-Fill" works perfectly too (expiry 1999).
Before the finger wagging begins, I should explain that I acquired the
mortal remains of a cart-wheeled Europa to allow me to develop repair
strategies for the compression fractured ailerons, flaps and tail. --
The time-ex'd epoxy was used on these. The resulting components are
indistinguishable from new-build parts. I keep test samples of each
resin mix in clear plastic egg-boxes, with encapsulated paper slips
listing date, batch no and component-used-on in each compartment for
trace-ability.
Here is a link to the Redux (Araldite) 420 data sheet listing the target
peel strength test figures:
http://www.ambercomposites.com/downloads/datasheet/araldite-420-tds-v1.pdf
atb
Nigel
On 06/11/2013 17:54, Andrew Sarangan wrote:
> Snip .....I am hoping someone can send me a small sample of unexpired Araldite
> 420 for comparative testing.
>
>
|