Porous castings, galvanizing and some weldments release air and moisture when heated. A pre-bake heats them above the planned cure temperature, often about 50 F higher, for long enough to empty the pores, usually 30 to 60 minutes. Parts are then coated while warm or after cooling, so less gas escapes during the real cure. It is the standard first move against outgassing.
Aluminum castings get a pre-bake at 450 for an hour, then shoot them warm with the outgas-forgiving gray.
Also heard as
- outgas bake
- degas bake
Related terms
Outgassing
Gas escaping from a porous substrate during cure and blowing pinholes, bubbles or craters through the film.
Gassy
Describing a casting, galvanized part or batch of metal known to outgas and ruin the finish.
Hot flocking
Spraying powder onto a part that is already hot, so the powder melts on contact and builds a thick film.
Pinhole
A tiny hole running through the cured film, often down to bare metal.