For some reason when I apply my final coating of buttercream after crumb coating it, my buttercream ends up looking streaky like it has different shades of the color I tinted it. How can I make sure it stays a solid uniform color? Thanks!

Well, you just have to mix/blend it more.

Add 1/2 teasp vinegar to it, it will keep it from cracking, too. HTH.

Are you smoothing it using a heated spatula/bench scraper? If you color icing, then use heat to smooth it, the heat can discolor the icing. The hotter the spatula, the more discoloration.

this also happens when the moisture content is too high.. lower the liquid or add a few tablespoons of extra powder sugar.

Actually, I mixed it very thoroughly and it still seems to streak. Is it because I tried applying it to the cake right after pulling it out of the freezer? I am so frustrated!!! Any other advice that might help?

I'll try putting more powdered sugar in it and also the vinegar. Thanks so much you guys-this hasn't happened before & it's a HUGE sheet cake so I really appreciate it!!