Epoxy

[P Josey]

In doing a search looking for info on epoxy for inlaying pegheads, some use the more expensive brands like West System. Is there a reason I shouldn't use the regular 2 part epoxy available from the local hardware stores?

[Gibson A5]

I'm sure there is a difference in them, but I just use a name brand and get the 1 hour slow set stuff so it has more time to sink/flow in and gives me time to work with it. The 5 minuite stuff kicks off too fast sometime and I waste more of it then I use. So far I have had good luck with the name brands.
Bill P.

[sunburst]

For inlay, any epoxy that cures fully and hard, and remains reasonably stable after it's cured will be fine.
For structural joints, or any purpose where it will be called on for strength, it's probably better to get a more 'expensive' type.

BTW, longer cure times can give you fewer bubbles in the cured epoxy around the inlays.

[arbarnhart]

There is more difference in hardeners than epoxies, but none of the fast curing stuff is very good (I question whether the 5 minute stuff is even truly epoxy; it seems too soft after curing). I like RAKA, which is cheaper than some of the high end stuff and does as well in the tests I have seen. The high end stuff has hardeners that dry with less blushing, which is a surface effect that you can clean up. But even the less expensive brands (like RAKA) have choices in hardeners.

[PaulD]

The nice thing about West System, System 3, and similar epoxies is that you can buy the epoxy and hardener you want for the temperature and cure rate you're after and that they are thin and can be thickened to suit your application. (At least the formulations I've used start out very thin) The downside is that epoxy has a shelf life... I can't recall what it is... ideally maybe a couple of years?... and I haven't seen West System in quantities smaller than quarts. LMII sells System 3 in 1.5 pint bottles which still seems like quite a bit of epoxy if all you're doing is inlay. If you're using it in some structural applications or under your finish that's not a bad size bottle. BTW: I'm not advocating between System 3 and West System... West has been around longer but in boat and architectural repair projects I've done I haven't noticed a difference. They're both good.

John makes the point that you want it to "cure fully and hard" so make sure you measure and mix it carefully or it will likely do neither.

pd

[8ch(pl)]

The big advantage to slower curing epoxies is that they give more time to mix the components. The hardening of the product is accomplished by an exchange of molecules between the 2 parts. This means that the ratio of Part A to Part B has to be exactly what the manufacturer says. Normally it is equal but not always.

When it is used Epoxy Adhesives must be mixed thouroughly and can be mixed again if they are left sitting for a short time. Five minutes is not too long. The mixing action can include pressing the stir-stick down into the mixture and forcefully working it together. A sturdy mixing stick may be called for.

[ErikAitch]

Here's my take on it; all other things being equal, use the best you can afford.

That doesn't necessarily mean the most expensive; IMO. It means finding a brand that gives the results you want (under your personal conditions) that is readily available where you are. But unless one's willing to do extensive testing, that's not much help, is it?

IMO&E, the most reliable is West Systems, but as has been pointed out, isn't quantity efficient. I've always been satisfied with Devcon's epoxy, but usually buy hobby shop bottled stuff for economy and reliability reasons, with the understanding that it isn't as hard as it could be. Hughes Associates 220 (amber) or 330 (clear) are standards for jewelers inlay work.

HTH

[arbarnhart]

[...] The downside is that epoxy has a shelf life... I can't recall what it is... ideally maybe a couple of years[...]

Shelf life for epoxy is virtually indefinite. Some hardeners have a shelf life, but properly capped, it is many years. I built a couple of boats several years ago and still have leftover epoxy from that. It works fine and I still use it for some pretty heavy duty household repairs.

[PaulD]

Glen; in my experience the better epoxies are not typically mixed one-to-one. If you buy the big bottles they come with metered pumps; one full stroke from each gives the correct proportions. That's great if you're laminating up a boat hull but for smaller project that usually results in a lot of waste. You can also use measuring spoons of the appropriate size or I think some folks weigh the two parts. The little tubes and syringes of cheaper epoxy are usually one-to-one.

Andy; I also have some old System 3 left over from boat projects that I use with good results, but I remember reading years ago that it has a limited life. Maybe that was hype to get me to throw out the old stuff and buy more, or maybe the manufacturer doesn't want to guarantee it after too many years. In either case, I'll continue to use it until it's gone or quits hardening.

pd

[Big Joe]

We used to use West Systems, but have found CBC brand to be better for nearly everything we do. It too has a shelf life, but works so well for so many things. We have been able to get it to release when desired also, but not under any other conditions.

[sunburst]

FWIW, I have some System 3 that's getting pretty old. There is a white solid accumulating in the bottom of the bottle of hardener, and it still seems to work fine. I mix by weight, BTW, and get much better results than I did trying to mix by volume.

For other less critical things, I have some 5 minute epoxy, in a double syringe type dispenser, that hardens very hard with no oily film on the cured surface. I don't know the brand, but it just came from the hardware store.

[arbarnhart]

I found this at the MAS Epoxies site:

11. What is the shelf life of these products?

The resin has an infinite shelf life and the slow and fast catalysts have a shelf life of 1 year in a closed container.

It is a common matter of debate in boat building circles (as is what brand to use, and if you really wanted to see a heated debate ask about using latex paint instead of oil based) and it's not unusual to find a builder who buys it in bulk and gets over 10 years out of a batch. The hardener is far less stable than the resin and prone to some evaporative and UV problems. I keep mine tightly capped in a closed cabinet. My understanding is that when it goes bad, you will know it. It will change consistency and/or have crystals form in it. But this is all second or third hand, I have never seen any that has gone bad and I don't personally know anyone who has had any go bad, but I do know someone who has some over 10 years old that's fine. My stash is about six or seven years old. I think the shelf life claims made by vendors is to absolve them of any guarantee and they use worst case thinking - if you work outside in the bright sunlight and uncap the hardener often it may only last a year.

[sunburst]

if you work outside in the bright sunlight and uncap the hardener often it may only last a year.

Yes, but if you are uncapping it to use it, well it may be gone in a year.

[amowry]

I've had some of the Stew-mac stuff for about three months, and already the resin is so thick that I can barely squeeze it out of the tube. Has anyone else used this stuff? It's another brand that they re-label, but I'm not sure what it is.