Nigel
Thanks much for your input, and the link to the strength data.
I had a similar issue with Aeropoxy, and was told by one of their reps
that it should not be a problem. The only change I have noticed is the
hardener (PH3660) turns red and eventually very deep red despite being
in the original sealed container. Although the bond strength appeared
to be good, the hardener is pretty cheap and easy to acquire
($35/quart) so that is what I did. But the Araldite 420 is pricey. It
doesn't seem possible just buy the hardener separately. The resin and
hardener comes as a single kit, and I was quoted $900 for a single can
---From the only US source I could find.
On Thu, Nov 7, 2013 at 9:02 AM, nigel_graham@m-tecque.co.uk
<nigel_graham@m-tecque.co.uk> wrote:
> 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-exd 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.
>
>
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