I have some pewter and brass pieces to blacken, and I was hoping to get them to be the same color. Are there any major differences in finish and color between the Jax Black and the Jax Pewter Black?

The Jax Pewter Black will definitely work on both the brass and the pewter and it will make them both the same color. For your information, the Jax Black will definitely work on the brass and MAY work on the pewter. The Jax Black will make the brass “blacker” than the Jax Pewter Black. There is no substitute for actually trying the chemicals on the specific metals you are trying to blacken.