"Is all epoxy the same?" Topic

Is one epoxy better than another?

Or is all epoxy chemically the same?

I have a clear epoxy and an opaque one that mixes to a gray. Are these just colors added for ease of mixing?

I don't have the foggiest about the chemistry involved, but the handful of off-the shelf ones available in Finland (= sucky selection) I've experimented with have had wildly varying properties, even within the 5-15 minute group. Araldit's stuff, for instance, seems to be more viscous across the board than the random no-name stuff I usually use for minis, and the exact hardness when dry varies as well. I don't stress test the stuff I've painstakingly glued together, so I have no empirical data on the strength differences, but no properly mixed batch of epoxy has failed on me yet, so they all seem to do the job of holding pieces together with enough adequacy that I can be reasonably satisfied.

Im sure the chemicals change depending on what kind of epoxy it is. From say, green stuff to the 5 minute epoxy to JB Weld.

I'd also think that 5 min epoxy should be different from 8 hour epoxy to 24 hour epoxy.

The base chemicals MIGHT be the same, but in different ratios for the task at hand.

When in doubt, hit up the company's website and hunt down a MSDS and Tech Data sheet, they should give you all the specifics about the goo in question.

I use slow drying epxy, as I usually have time, and I like the ability to make adjustments. Also, my wife hates the smell of the 5-minute version.

It's a funny thing: for years I used LePage's epoxy, which was the brand most available in Canada. It was also a very good epoxy; much better, in my opinion, than Devcon. The problem is that now that LePage's has been taken over by another company, they seem to have forgotten how to make tubes.

The last two I bought, I had trouble with both the resin and the hardener leaking out of their tubes, making a big sticky mess. In the end I've switched to this American-made product in squeeze bottles. I can't remember the name (something-Smith; it's the company owner's name, apparently). I don't think it's as good as LePage's, but at least it stays in its bottles.

The best I have found in the US is Devcon 5 minute in the syringe applicator.

Rabbit

I also use Devcon 5 minute epoxy (UK), I get mine in great big cannisters, lasts for ages, will stick anything.

Epoxies come in a variety of curing times for different applications. A fast as 2 min. to overnight (12 hrs). The rule of thumb (who is that guy named thumb, anyway?) is the slower the cure time, the harder the resin. This may work against you with figures, as harder also might mean more brittle. I find that the older catelyst of opened containers seems to loose its' potency. You could probably find industry standards on the net. They are out there for plasters from US Gypsum. I found it very interesting that harder plasters have a lower sheer impact damage quotiant, for instance.

No, all epoxies are not the same, nor are all 5 min general purpose epoxies the same.

See here: TMP link

I have to say, though, that I have found an even better replacement than the old Loctite formula, and that is Devcon 5 minute epoxy in bottles:

link

1) This stuff lasts FOREVER…

2) …because it is much less sensitive to the ratios being off. Loctite was great, but you had to have a fairly close 1:1 mix, causing me to mix much larger batches than needed. With the Devcon stuff, I simply mix about what I need and it always works.

I been using a $12 USD pair of these from Lowe's since…well…about when I posted that last thread, last August or so. I used to walk out of Lowe's with 6 Loctite syringes at a time, and could go through one in a week.

Oh, and on the grey coloring, I believe some epoxies include metal or other fillers in the epoxy to make it stronger. That may be one of them?

Adhesive chemistry has had an explosion of innovation over the last 40 years. There are all kinds of epoxies, as well as other glues, usually specialized for industrial processes.

As far as consumer varieties, the big choice is between 5 min and 1 hour curing times. The 1 hour is a bit stronger, but impractical for minis. It is far more waterproof, however, if that is important to you.

Colored ones are going to be adulterated with whatever provides the color, presumably reducing their mechanical strength. Sometimes the additives are there to make the epoxy thermally conductive or add other special properties. Probably clear is best.

Fillers like talc, powdered cellulose,starch etc. all make the epoxy opaque & cheaper for the manufacturer. Some aditives can make the stuff strong & bulkier like 'micro-balloons'. Take a look at the 'West System' home page for add-your-own fillers.

I rather suspect that there are other adulterants that can be added to epoxys that remain clear but increase bulk & reduce manufacturing costs, but manufacturers aren't going to talk about them, specially if they reduce strength or product life.