How long until the epoxy reaches its full hardness and scratch resistance?

UltraClear Bar & Table Top Epoxy is 99% cured and ready for use after 72 hours above 75°F. That is when restaurants and bars re-open and put the surface into daily use. Reaching the full 100% cure and the final Shore D hardness rating of 98 can take several months depending on your environment; a cool or air-conditioned room slows it down. You won't notice the difference by feel, but scratch resistance and heat resistance (up to about 135°F) don't peak until the epoxy is fully cured.

The early stage of curing is the most critical, so use coasters, placemats, and trivets at all times during the first few months, and never use the epoxy as a cutting surface.

If your top is marking or scratching easily in the first weeks, early cure may be a factor, assuming the epoxy was applied according to the directions. Two other things to check:

Application. The epoxy must be poured on and allowed to self-level to its intended 1/8-inch depth. A seal coat can be brushed, but a spread or troweled final coat cannot cure properly, and a brushed-on final coat is not smooth enough to be the finish. The fix is to scuff the surface with 220 to 320 grit sandpaper, clean it with denatured alcohol or acetone, and pour a fresh flood coat, which self-levels and cures glass-clear again.

Cleaning. Even fully cured epoxy can be scratched by abrasive materials, certain cleaning methods, or harsher cleaning products.

Cure time details: https://ultraclear.helpscoutdocs.com/article/228-cure-time-epoxy