hi i do powdercoating, everything i coat, will go in the oven before i coat it, on cast aluminum (wich is close to magnesium)to prep it for coating, i only blast it with aluminum oxide, then cook it,blast it again,clean and prep it for coating, reheat it to make sure it has out gassed,bring it to 300degrees and shoot it hot.

i find the biggest problem is water,oils or solvents can be removed with just about any thing and remnants can be burned off, just like when welding aluminum or mag the part needs to be preheated to remove water.