The materials below are some that I would normally recommend for increasing the emissivity of materials.
- Scotch 33 Tape Consistent emissivity of 0.95
- Glyptal Enamel Paint Electrically insulating paint
- Dye Penetrant Developer This is easily applied and removed. It has a very high emissivity
- Paints, various paints can be used
- Some deodorants can be used, usually ones with alumina powder or similar.
- Foot powder, this can be brushed off easily when finished.
- A light film of oil, or water can be used.
If you can think of any others, please post them below