Q: What type of chemistry one should use for below absolute temperature (i.e., 0°C up to -30°C)? I’m looking for a glossy and semi-glossy finish.
Should I go with pure polyester, or hybrid? Will superdurable PP work? Or should I go for some higher percentage of resin, around 80%?
A: I would start with a 50:50 hybrid with minimal (but some) filler such as blanc fixe or perhaps mica. A 50:50 (polyester to epoxy) hybrid will provide toughness, adhesion, and thermal stability at a relatively low formulation cost. It can be formulated easily in a gloss or semi-gloss product and will provide the best flexibility and toughness for the price. I would be careful not to incorporate too high a concentration of filler. Some filler is good, but excessive amounts will compromise flexibility, toughness, and corrosion resistance.
Superdurable polyesters provide excellent resistance to sunlight and intense UV radiation. They typically possess significantly less flexibility than other powder chemistries, however, including epoxy, hybrid, and pure polyester types.