I am trying to find a clear, pourable epoxy resin that has the highest Shore Hardness rating. This us a concern for any countertop, river table, cutting board – anything that can scratch when someone is cutting on it with a knife. The way epoxy’s are labeled is often misleading, and never contain a Shore Hardness rating ygat obe can use to readily compare.
So, what epoxy resins have the highest Shore Ratings (without regard to the thickness required)? AND would epoxy resin be made harder by appying urethane over it?
Yes, it’s a minefield. Part of the reason is the cost involved in doing tests to industry standards; I’m sure another part is that if the product doesn’t stack up well, why to publicize it.
I doubt you’ll find a league table. Some epoxy manufacturers Shore test their products and are very vocal about the outcome, suggesting they’ve performed well. I’d still ask to see the technical datasheet to check that a reputable testing agency did it.
Check out these companies as I know they have epoxies in the 70 – 100 Shore Rating:
This one may be more hobbyist, but their product comes in at 75: https://www.artmolds.com/kastez-casting-resin.html.
As to your question on urethane increasing the hardness, I’ve never tried, and I’m not sure it would.
Polyurethane is more resistant to scratching and impact than epoxy, and it will age better. It also has better UV resistance. It may be a good protective layer, but I’m not convinced it will do anything to the epoxy hardness. However, that’s only an opinion with no chemical knowledge to back it up.