Powder Coating Extrusions

Q. I powder coat aluminum extrusions. The cleaning process is 80-grit aluminum oxide blast followed by a phosphate wash and rinse. Do I have to wait a specific amount of time or complete an additional step after the rinse before I apply powder? –L.W.

A. Generally, the preferred method is to perform cleaning prior to mechanical finishing of a part, otherwise you run the risk of driving some contamination deeper into the aluminum surface. Some extrusion processes could leave behind residue. If the part you are receiving is already sufficiently clean, the pretreatment you described sounds very good for powder coating. It is very important that the part be thoroughly dried prior to entering the powder coating booth, but you does not need to wait for any specific length of time prior to that. Generally, it is better to get the part into the powder booth as soon as you can following the cleaning so it does not have the opportunity to pick up debris from storage.