Jan 20, 2019, 10:15 PM | |
Registered User Thread OP | Discussion Ive got a bunch of epoxy on my shelf. Its been hot and cold over at least a couple years. How does epoxy go bad? I will probably test it first, but is there some know facts I dont know about epoxy expiration? Thanks |
Sign up now to remove ads between posts |
Jan 20, 2019, 10:31 PM | |
If it flies, I can crash it.
| If it's hardened it's no good. Other than that, the bottle might have a "best by" date on it someplace. But unless you're gluing something that needs to withstand a lot of stress, if the resin and hardener are still liquid, you ought to be good to go. I know I have some hobby epoxy that's going on 5 years old and it still glues things just fine. |
Jan 20, 2019, 10:42 PM | |
Scott
| Jim, most resin systems list a shelf life of 12 months, and are pretty much done at 24. The resin should still cure, but the tensile strength will be less than half of what it was when the resin was fresh. If it is a quality laminating resin I would toss it at 18 months. If it is hobby store minute resin, which is pretty much junk when new, I would toss it at 1 year. I use laminating resin for all my carbon and kevlar laminations, and thickened as an epoxy glue. I draw the line at 18 months. I can tell the difference by then in the finished component. Scott |
Jan 21, 2019, 10:09 AM | |
Bellanca Kruesair
| Jim the good old 'test first' adage still applies, here..... Nuke it in a microwave for 10 - 15 seconds. Mix a batch, and glue two pieces of scrap wood together in a 'Cross'. Tomorrow, break them apart.. If wood fibers tear from both pieces , it's good ! Next time, build faster. No one should have epoxy for two years.... |
Jan 21, 2019, 11:23 AM | |
The Junk Man
| Quote: I would hesitate to state "most" expire. Indeed, if i had to tag any resin characteristic as "most", I would say most do NOT expire after 24 months. WEST Systems have done extensive research on their products, for just one example, and found 15 year old resin to be perfectly usable. Sometimes various hardeners will change color, but still keep right on working. Tom |
Jan 21, 2019, 12:06 PM | |
Registered User | Quote: I would hesitate to state "most" expire. Indeed, if i had to tag any resin characteristic as "most", I would say most do NOT expire after 24 months. WEST Systems have done extensive research on their products, for just one example, and found 15 year old resin to be perfectly usable. Sometimes various hardeners will change color, but still keep right on working. Tom My experience with dated epoxy is the same as Tom's... .. shelf life is typically a lot longer, it depends on the specific epoxy and, as already stated, make a test glue up first. Michael in Ontario, Canada |
Jan 21, 2019, 01:09 PM | |
Pro Hoarder
| Hi Jim, |
| | Latest blog entry: In flight |
Jan 21, 2019, 01:54 PM | |
B for Bruce
| I've never had any issue with old resin either. And some of mine is well over 10 years old. In fact I found a box with tubes of Petit Hobbypoxy 5min a few years ago that I'd bought back in the mid 1970's and misplaced on a shelf in the wrong (unrelated to adhesives) storage bin for about 30 years. I opened it about 4 years ago and used it for the very first time and it's been fine and I continue to use it. In looking around on the web some suppliers make mention of MINIMUM shelf lives of their epoxy resins that are in line with what Pylonrcr posted above. But then again there's lots of mentions of decade and more old resins that perform just fine. I assume that testing has been done on these resins by the makers aimed at their use in aerospace applications and that there must be some amount of degradation in at least some of the properties. But how much that is isn't clear from a quick search. One thing is that when stored in a cold room I've had various bottles crystalize on occasion. The standard fix for that is to put them in some hot water and let the heat re-dissolve the crystals. After that it's good to go again. And this is in fact a fix I found suggested by at least one of the makers in the quick search I just did. All in all though I'm going to keep using my old epoxy as long as it continues to cure. |
Jan 21, 2019, 02:28 PM | |
Registered User Thread OP | Thanks everybody. I did look online and read West systems explanation that their stuff is still good long past it’s “best by” date. Pacer Z-proxy says one year. But I’m skeptical since they want you to buy more new glue. I had read things before that it might darken, might solidify, or show crystals, but wasn’t certain if there was some info out there I hadn’t heard. Earl....that leads me to a second question...if I use epoxy or gorilla glue or titebond, the wood is going to fail first in all three cases, is it not? So wondering exactly where epoxy is needed over the other adhesive choices. Also—It took me several years to get through all the garbage leading to a divorce just before the holidays. So I put up a workbench and I’m back at building. I’m sure I’ll use stuff up before it goes bad now. Actually thinking about a second work surface and a second build, so I can be doing one while the other is drying. |
Last edited by JimF; Jan 21, 2019 at 02:37 PM. | |
Jan 21, 2019, 05:03 PM | |
Registered User | What are you doing with the epoxy? If your gluing something together you'll want a structural adhesive, I use T88 |
Jan 21, 2019, 05:22 PM | |
Pro Hoarder
| Jim |
| | Latest blog entry: In flight |
Jan 21, 2019, 05:33 PM | |
Registered User Thread OP | TN If I were going to laminate and install a ply firewall (balsa/light ply fuselage) Id use epoxy. I’m trying to decide if that same firewall could be installed with Titebond or PU glue if I’m going electric. Similar question about joining wing halves. Of course I’d use FG and epoxy resin to reinforce the joint, but I think the wood would fail first no matter what glue I used to join the halves. And finally, landing gear. I’m pretty much done with CA and would like to use as little epoxy as possible. |
 - Which law would you use to simplify the expression mc^(006)-1.jpg?... (1 Answer) | Transtutors)