Reactive metals have an etching compound that will clean the surface of your niobium. That should get rid of the splotches so long as you do not touch the surface with your bare hands. As for the difference, try gang anodizing. Where you clip the leads together in a line, and then dip them all at once into the solution. That way they all are being anodized at the same time for the same amount of time. I’m sure Noel will have further instructions. I got her DVD, and then watched everything Reactive metals had on their website. But be warned that I had experience with anodizing before. It was due to a reactor being given to the local makers space that got me working with it again, so i could show the rest of the people how to do it. It’s fun and easy to do. BUT read and watch the clips before you try blindly to do it. It will answer most of your questions.