Is epoxy inert once set?

I have here a brand new container of two-part epoxy resin. It has a “this product contains” warning on it – something I don’t recall seeing before on epoxy labels. Might be a new ingredient or a new regulation, I don’t know.

What I’m wondering is, once the epoxy has hard-set, is the bad chemical inert? Generally, encasing things in epoxy does that, but who knows if that applies here?

Anybody know? Label says “contains epoxy resin, aliphatic amines.” Looking up aliphatic amines, I see that they are indeed carcinogenic. I’m assuming they would be in the hardener.

It would depend on what, exactly, is in the particular epoxy you are using. And yes, this is basically a bump in hopes someone with more chemical knowledge will chime in.

Aliphatic amines are carbon (organic) compounds that contain at least one nitrogen atom attached to a saturated hydrocarbon backbone. In epoxy resins they are used as a room temperature curing agent to accelerate and increase molecular crosslinking which is what makes the epoxy rigid after application.

An epoxy will continue to crosslink and outgas volatile organic compounds even after its primary curing is complete (i.e. has reached full tensile strength) albeit at progressively lower rates. This may produce an odor temporarily but the amount of volatiles released from a modest application of epoxy is so tiny that the threat to human health is negligible. This is really only a problem in confined spaces and with sensitive instrumentation like optics where even a single molecule layer of contamination can degrade measurements. The application of a modest amount of heat will accelerate the outgassing process; in satellites and avionics equipment, they are subjected to a thermal cycle to bake out volatiles in order to protect from outgassing contamination.


I think the simple answer is “Not strictly inert, but fairly close to it.”

Note that this applies to normal temperatures. At sufficiently high temps, cured epoxy softens, deteriorates and eventually burns.

Yes it is inert. The curing process caps any harmful chemicals. Nearly all epoxy resins are based off of TDI or MDI (toluene diisocyanate and methylenediphenyl diisocyanate). These are thermosets not thermoplastic, meaning they burn when reheated instead for reverting back to its original constituents.

As a frame of reference these chemicals are used in all sorts of foam components. Your pillow, bed, car seats, sofa all have these toxic chemicals in them but once they cure they are inert.

We have a Thermogravimetric Analyzer in our lab. It can measure how well an epoxy is “cured.” More info here.

Not disputing any of the above, but just to add, there are sometimes extra ingredients in Epoxy-resin products which are added to thicken them, adjust their setting times etc.

Regardless of additives, it’s also true that epoxy resins are a family of chemicals, rather than just one thing with exactly just one set of properties.

In cases where the finished resin will be in contact with foods, for example, there are ‘food-grade’ formulations. They are just a subset of the type - and some formulations are probably accidentally food-safe just because of what they are made from - but the food-grade types are specifically formulated for factors such as to try to minimise residual uncured monomers and so on.