Can the epoxy repair a cracked sink, chipped marble, granite, or plastic?

No. UltraClear Epoxy is a liquid resin that is poured out over flat, level surfaces and cures over 72 hours. It's made for top coating bar tops, table tops, and countertops, and it is not an adhesive or a repair resin.

Sinks: the epoxy can't be applied to a sink, whether you want to recolor a composite sink or fill a hairline crack in it. You could coat the countertop around the sink with UltraClear Bar & Table Top Epoxy, but not the sink itself.

Marble, granite, and stone: bonding a chip back onto a marble sink or joining the broken pieces of a granite statue calls for an adhesive epoxy. Ours isn't one, and we don't carry a product for that or have experience in that area, so we can't recommend one.

Plastic: resin does not adhere to plastic surfaces, so the epoxy can't be used to repair or stiffen plastic, such as a cracked plastic sign. The full list of surfaces the epoxy can be used over is here: https://ultraclear.helpscoutdocs.com/article/111-epoxy-surfaces

The same goes in reverse: we don't recommend mounting or gluing anything, such as a drink tray, to a cured epoxy top, and we have no adhesive to suggest for it. Anything like that is done at your own risk.

If you have a flat surface you'd like to coat, we're happy to help you plan it. Adhesive resin for repairs falls outside what our products do.