Cold enamel looks and feels like traditional enamel, except it doesn't need a kiln for baking. You can put a cold enamel finish on most types of material including cardboard, wood, metal and plaster, according to the website Home Crafts. This provides crafters an easier way to give projects an enamel finish without the expense of owning a kiln.
Mix exactly one part cold enamel hardener with two parts cold enamel colour in disposable mixing cups. Since an exact ratio is essential for proper hardening, it's best to find small disposable measuring cups so you can measure the mixture right in the mixing cup. Stir well.
Let the mixture sit for about ten minutes to eliminate all the air bubbles, so you don't wind up with any in the paint.
Paint your desired object using your paintbrushes. If you're new to cold enamel work, begin on a small object and work towards creating larger, more ornate things. You can only paint with the enamel mixture for about an hour before it hardens too much, so mix only as much as you think you'll use in that time.
Allow your finished product to dry and harden. This takes about 24 hours. If you want a shiny, glossy enamel finish, leave your project alone for the entire 24 hours. If you want a duller finish with a matt look, wait about three hours. Then hold the object in front of steam from a pot or kettle for several minutes. Let it harden the rest of the 24 hours, and the finish should lose most of its shine.
Cold enamel does not work on rubber or PVC plastic.