Using stale resin
 

Hey guys. I have about 3 gallons of vinyl ester left from last year. I'd say it is about 10 months old. It has been stored in my cool dark basement. Think it's still good? What happens to it when it gets old? I know they say like 6 month shelf life. What will I notice if I make some parts with it?

If it's good and clear it's probably ok but if it's milky or lumpy in any way it's toast.

So I guess my question is, what is "toast" exactly? I've used 3 year old poly with crunchies on the cap that was thick as molasses and it "worked". Granted I only did that making custom car stereo stuff that did not need to be structural. What happens to it? What properties does it lose or gain when it gets old. Obviously if you add mekp to it, it will still harden but clearly the end product must be deficient in some way. I'd just hate to toss 3 gallons of vinyl ester when maybe I could use it to make parts that are not as crucial as others.

I am sure there is some chemistry based answers to the question but from my perspective it is very difficult to get thickened resin to wet glass fibers adequately due to the increased surface tension of the thickened resin. I know for sure that moisture contaminated resin will not harden properly regardless of how much MEKP you mix it with.

mr basketcase your name is da meening of "toast" which also meens kaput, shot, fried, and on & on & on
ka·put
kəˈpo͝ot,käˈpo͝ot/Submit
adjectiveinformal
broken and useless; no longer working or effective.
synonyms: broken, malfunctioning, broken-down, inoperative;

in otha words da glass juice is shit

sam

Somewhere I have a response from U.S. Composites on this very subject. If I remember correctly they stated that as long as the resin wasn't lumpy or gelled, it should be OK. They also mentioned that the MEKP usually goes bad before the resin, and a quick way to check it was to vigorously shake it and see if it kept bubbles.

Mix the resin thoroughly and run a little test batch to see what happens. If it cures properly, I wouldn't hesitate to use it on little, non-critical parts. I did that once and my test batch kicked off just fine, but when I laminated with it, the part didn't cure until I set it in the hot sun for several hours.

I was told the same by USComp.

MEK is critical obviously.

https://en.wikipedia.org/wiki/MEK


MEK is a solvent,NOT a "kicker"


https://en.wikipedia.org/wiki/Methyl...etone_peroxide

MEKP is a "kicker"

big difference....

Good info. Thanks guys. I guess I'll run a test batch and see what happens. I think I have a good chance, given it's storage conditions.

I have took year old resin and ran it threw a screen to get the trash out but only used to do non critical parts or small throw away molds. Always try a small test batch to be sure it will kick. If it takes a long time to kick off, I would not risk it on a big lay up.

Also GFS don't forget the "P" some love to talk about the p :D