I'm not sure if I misinterpreted your post, but it sounds like you are heat-treating the blade, and you are getting a black coating on it which needs to be ground off along with the pattern. If this is correct, then I have some advice. If I'm not correct, then ignore my rambling.
After heat-treating the blade, one can expect the black coating along with a pattern, but, depending on the design of the knife, most makers polish the blade or do some more grinding followed by polishing. The pattern is brought out by soaking the blade in an acid or a solution of an oxidizing salt such as ferric chloride. This treatment delineates the layers and produces, along with some fine sandpaper, the final pattern on the blade.
Good Luck!