Hi. I just stenciled black royal icing on golden yellow cookies. I thought my stencils were totally dry, but see there are splotches that werent there before. Can I steam the cookies to remove the blotches and add some shine like you can for fondant? Would this cause bleeding?

Any other tips to make the finish more uniform?

I doubt you can steam the splotches out. 

What caused the problem probably was the stencil was not *completely* adhered to the icing.  Tiny openings allowed the black to go under the stencil just enough to tarnish your yellow icing.

About the only thing I can think of now is to *VERY!* carefully brush over the black w/more yellow.  Use a very fine art brush, then smooth w/your finger.  Hope that works for you.