Making a nailpolish cake for my DD's birthday this week. Want to make the handle black, but never been able to get a really deep black color and if I get it sort of dark, it tastes gross. Tips?

I thought I read on here somewhere to start with chocolate frosting and color it from there. Thoughts? If I use a can of chocolate frosting, will it crust?

To get a deep black, start with chocolate frosting then add black food coloring. You won't have to add a lot. I don't use can frosting, but from what I have seen it doesn't crust.

You might ned to try out a few different brands of food color, there are some out there that don't taste so bad. I'm not sure if this is helpful or not but one time I didn't have quite enough black coloring for an order so I tossed in red, blue and brown gel color in with the black and it came out really dark and a true black color and didn't taste so bad. I'm still trying out different brands- Deco-Pac gel colors are just the best but I can't order them since I no longer work in a commercial bakery and they only do orders for commercial bakeries....So far AmeriColor is okay but not as strong and I refuse to use wilton brand colors they are yucky and too expensive.
As far as using canned chocolate frosting...it might crust...in a day or two or three, lol. You can probably make it crust by beating in a couple cups of powdered sugar and adding about a 1/4 cup of liquid.

You can use whatever frosting you normally would use and just add cocoa powder to it before adding any black coloring. You can get frosting pretty dark with the cocoa so you won't need to add too much black color, preventing the nasty taste and/or creating a sticky mess. I have done this with SBMC and Royal. Not sure if you normally use canned frosting, or maybe just planned to use it this time..? But you can do it with any frosting, in case you don't like to use canned.

Thanks for the tips. I always make my own vanilla buttercream because the canned stuff tastes icky and doesn't work well, but sometime for chocolate if it is just an accent, I cheat and use the canned stuff since it tastes good to me. I don't have access to other brands of coloring...I just use the Wilton. Because the black part needs to stack on top of the cake (it will be the handle part of the nail polish bottle), I need to make sure it crusts to I can move it into place. I think I will try to make my own chocolate frosting using my regular BC recipe but adding in Dark Chocolate Cocoa powder to help get a really deep chocolate and then try to go from there for the black. Worst case is that it is a brown/black and that might look okay with the blue "nail polish" color that my daughter has requested.

We use powdered black food coloring to make black frosting, unlike the gels it does not affect the taste of the frosting.

I already made my chocolate "black" frosting, but for the future, where do you get powdered colorings?

It came out okay. I used dark chocolate cocoa so it started pretty dark and then added black. The gel changed the flavor a little, but the frosting is so rich, it is hard to tell the difference. It wasn't super black yesterday, hoping that today it will be a little truer color.