Preheating a part above the powder's melt temperature makes powder fuse the moment it lands, which lets sprayers build heavy films, coat Faraday areas without relying on charge, and cover castings after an outgas bake. Film control is harder and runs, sags and uneven gloss are common. It is also used for second coats when back ionization stops normal build.
Castings came out of the pre-bake still hot, so we hot flocked them and the pinholes were gone.
Also heard as
- hot flock
- preheat spraying
Related terms
Pre-bake
Heating a casting or galvanized part before coating to drive out trapped gas that would blow holes in the film.
Fluidized bed
A tank of powder kept airborne by air blown up through a porous floor, used to dip preheated parts.
Faraday cage effect
The tendency of charged powder to avoid inside corners and recesses because the electric field bunches on nearby edges.
Film build
The thickness of the cured coating, usually given in mils or microns.