Bad Epoxy?
 

Hi friends, I have been building since 1989, This is the first time I ever had a problem with Epoxy. I bought some 30 min.epoxy from Great Planes,and when it is cured,its as brittle as Glass. I used epoxy of all kinds before,but none that had this carateristic to it. Maybe I had a bad batch. Any input would be great. Thanks.

Never had had problem before, I'm starting to use this Epoxy call Six10, it doesn't run and full cure is 24 hrs, it's intended for marine use, to repair cracks on fiberglass boats.

Shelf life perhaps? It may have cured very hard but the real test of a glue is the joint strength. A puddle of the glue may be quite brittle but still be strong in a properly set up joint. That said,given the small quantities that we usually purchase for our hobby you may be happier just buying some new epoxy.

Thankyou for the advice. Im going to use Devcon from now on. Expencev,but good stuff

Some years ago, I had some 5 min epoxy that cured to an overly brittle mess. When cured you could easily pulverize it like you would a sugar cube. Only time I ever saw anything like that. Very isolated incident though.

I've used many different brands over the years with mostly excellent results. Use mostly Bob Smith or Zap products these days with good results. Widely available at an acceptable price.

I have had the resin crystalize over time, a shot with a heat gun return it the original state. Is it both parts or only one?

I prefer to use BS or Zap as well, both very good products. I would check the expiration date as was mentioned. When you mixed it was the ratio correct and was it warm enough in your shop while it cured?

I mostly only use 30 minute epoxy when I use epoxy, I prefer T-88 epoxy and that is my go to epoxy.
If you got they mix ratio wrong the epoxy could become hard and brittle, or if they packaged the wrong hardener you could also end up with brittle epoxy.

Lets see, you have been building since 1989- that's 28 years. In 28 years you got, or mixed, one bad batch of epoxy and you are ready to switch brands???? How many bad servos or bad pieces of balsa or bad battery packs have you received over those same 28 years?? Did you switch brands each time?

Epoxy
 

Maybe your right,but I might switch to something differrant . I had all of my epoxies on my table at once,30-15-and 5 min,I might of mixed the wrong resin with the wrong hardner. Bad mistake on my part.

While not always the case, in many brands, the resin is the same between several different cure time epoxies. Only the hardener determines the cure time and to a degree the strength and flexibility. There are some good informative articles available at the various companies web sites that explain their products.

I once mixed up a batch of epoxy with resin and hardener from different types. It produced a crappy result, my guess you did the same thing. Also will second the suggestion that you get the proper ratio (usually 1 to 1). The brands mentioned earlier are all pretty good. Will just add another to the list I like to have is West Systems West System G/Flex liquid epoxy

https://www.jamestowndistributors.co...uid+Epoxy+Kits

I buy the 8 oz kit for $18.99 It does dry amber in color.

Great when you need lots of time (sets in a hour, do give it a whole 24 hours, I like 2 days before I try to sand it), but it's damn strong and remains a bit flexible when cured. I particularly like it for firewalls, dihedral braces, setting horizontal and vertical tails, and hinges. Because it gives me plenty of time to get things just right. I've even use it to fuel proof.

I switched over to Bob Smith/Mercury adhesives and probs like you are having have gone away.. I've also had probs with GP CA Switched that also.

dick.

I agree, I only use epoxy where needed. Cuts down on weight. I use dubro hinges on all my models, I made a custom hinge guide using 2 peices of 1/2 in. aluminum angle. I also an extreamlly small dreamel bit and it works great and fast.

Thanks for the info friend. Lucky