The best replacement for hardener is activator.

The best alternatives to hardener are rated as following:
★★★★★  activator
★★★  integral color
★★  nail strengthener
★  clear coat

Your alternative for hardener is not listed? Suggest!
Speaking about hardener, one probably shouldn't forget about acrylic.

Other search terms related to hardener and their ratings are:
★★★★★ acrylic
★★ resin
★★ rustoleum
★★ clear
★ acrylic enamel paint
★ oil enamel
★ acrylic enamel
★ tremclad
primer
resin fiberglass
You have in mind a companion for hardener and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of hardener in all years. Click on graph for more.
hardener
activator
integral color