[Livinincolor]

Those valve covers are very nice and I have done pieces like that the same way. Coated the whole part and then removed the coating from areas that I wanted raw.
However, I have found that to polish the letters or raised area that doesn't need coating, it is easier (for me at least) to process them (polish and tape) first. The problem with removing coating materials after the piece has been coated, leaves **** in the piece from the removal process and is difficult to remove. MAybe it was just because it was a rough finish like above and not smooth.
I once did a vavle cover and then polished the raised portion after curing. The polish process left a mess that was very difficult to clean off.
Now, if I want the letters raw, I polish them first, make them look all pretty, tape them off and then coat the piece.
Trial and error is the best way to learn powder coating! And always keep good records of time of day, weather, heat, powder manufacturer, etc. I have found it helps a lot!!!!