Bondo Marine Epoxy?

I found that I had a reasonable amount of this stuff left over from a rather old project:



I have four unopened can sets (resin/hardener) and one opened set. All were purchased back in the 2002-2003 time frame. There is no shelf life printed on the cans. There is a number on the cans that appears to be a product number, 3202, which appears to be no longer made by Bondo, but their current product numbers resemble it.

Any idea whether this would be suitable for use on fairings, tips, and maybe even the cabin cover/doors on my RV-10? I recently cleaned out my old garage and found this stuff; not sure if it is any good. Any knowledge you have would be appreciated. Are there any tests that can be done on old resin or test coupons made with it that would show whether it has degraded over time?

I wouldn't risk using it Dave. I would discard and go with fresh resin and hardener. I had a 6 years leftovers of West System but the containers were half empty. It didn't fully cure after weeks and weeks and I scraped it off. Will look for pictures...

1001001 said:

on my RV-10?

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Did I miss something along the way? I didn't know you were building a -10. SWEET!

Resin stored for a long time will form crystals which can be dissolved by heating it in a water bath. I would warm it up to dissolve any crystals, and then do a test batch and see how it cures.

Thanks for the quick replies guys!

It's not terribly important to me that I use this stuff, but if it can be used for non-structural items, it might save me money. Not sure how I feel about using it on the doors and cabin cover.

I'll try warming it up and do a cure test, but I probably won't spend a lot of time trying to make it work if it doesn't look good right away.

Weasel said:

Did I miss something along the way? I didn't know you were building a -10. SWEET!

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Yup; just finally got started building after spending most of my time working on some other projects including winterizing my shop and getting my instrument rating.

project blog here: http://www.brunbergs.net/?cat=14

I can't wait to get this thing flying!

West Systems, which most of us use, calls their epoxy a 2-part marine grade epoxy, so no problem using a product that says it's for boats.

Speaking of boats, I've seen guys on boat forums say they have used epoxy that is 20 years old with good results, provided it's been stored in sealed containers. The hardener may darken, but the stuff still works fine. System Three, another epoxy manufacturer, says their product has an unlimited shelf life, provided it's stored in sealed containers.

I'd mix up a batch and try it on some scraps of fiberglass and see if it cures and hardens properly. If you want to do a comparison, you could also do a test with a small batch of recently-purchased West Systems, then compare the two and see if they seem to have the same strength. I know this isn't totally scientific, but it should give you a pretty good feel for whether or not you can use the old stuff.