Resin Shelf Life Experience

[Mark42]

Over the years I have read about shelf life of polyester and epoxy resins, and how they have fairly short shelf life. That made me a little anxious about $150 worth of epoxy resin $30 of poly resin I have left from last season knowing that I will be working on the boats soon.

So I just wanted to post a quick message to let you know that both the polyester resin and epoxy resin I bought last spring are still working fine now. I had the opportunity to mix up some of each in the last few weeks, and neither performed differently than they did last summer. Each is a year old.

Both the Bondo brand poly resin (1 gallon can) and fiberglasssite brand Epoxy resin (3:1 mix) held up fine stored in a cool, dry basement over the winter. There is no discoloration or clouding of the epoxy resin, it is still crystal clear. Cure time is the same, and strength seems to be unaffected. I used the epoxy resin with a little thickener to fix a broken cast aluminum differential housing while a replacement was ordered. Got the new part, and the epoxied piece is still in service!

The Bondo resin is still as crappy as ever, but works fine too.

 

[ondarvr]

Re: Resin Shelf Life Experience

The listed shelf life of resin can be a little misleading.

When its first made it needs to meet certain specifications that are important to the companies that buy it, either the resin is formulated to meet their needs, or their production methods are adjusted for the resin.

As the resin ages it may change, typically the viscosity will drop and the gel time will get longer, this can have a huge impact on production, so the resin manufacturer needs to state the length of time the resin can be expected to meet the original manufacturing spec.

These spec's aren't quite as important in a DIY project, so the actual time you have to use the product up can be much longer.

In hot climates the resin may start to develop chunks much sooner though, so like M42, store it in a cool ( the cooler the better) place and it should last a while.

Longer gel times may lead to a somewhat poor cure though, so keep an eye on that part of it.

 

[lckstckn2smknbrls]

Re: Resin Shelf Life Experience

So your saying the 30 year old resin I have might not work? lol

 

[Mark42]

Re: Resin Shelf Life Experience

So your saying the 30 year old resin I have might not work? lol

Nah, its just fine. Might take a year to kick off, but its just fine...

 

[lckstckn2smknbrls]

Re: Resin Shelf Life Experience

Should I add more hardener? lol
I'm starting work fiberglass work on a 10' hydroplane. I knew I had some fiberglass cloth at my dads from 30 years ago. He said he would bring it over. I guess the resin was there too.

 

[Reel Kahuna]

Re: Resin Shelf Life Experience

I bought a gallon of polyester resin and hardener from TAP's plastice two years ago and opened the cap twice to do two glass work and just yesterday I opened it again to do a little more glass work but it was thick as snot. Needless to say, I threw it out and bought another gallon from the local auto parts store which btw was cheaper than TAP's plus it included the hardener.

 

[lilboatsman]

Re: Resin Shelf Life Experience

Should I add more hardener? lol
I'm starting some fiberglass work on a 10' hydroplane. I knew I had some fiberglass cloth at my dads from 30 years ago. He said he would bring it over. I guess the resin was there too.

Just add a bunch of acetone, soften right up! Joking ofcourse.

 

[Mark42]

Re: Resin Shelf Life Experience

My understanding is that polyester resin is continually hardening. Hardener just speeds up the process. So old resin is partially hardened resin, and probably not very good.