cause when i try to make black using the WILTON brand of coloring first it' turn into gray then when i add again some coloring it's just the same result ..

Well i usually buy colors like red or black fondant just cuz its hard to get that prefect bright red and black tends to fade... Def wiltons black isnt good.. Try americolors...

For black fondant I start with chocolate MMF using Rhonda's Ultimate recipe. I have had good success with this.

If you're going to make it you need to start with chocolate or brown fondant but I'm with kneehah. Just buy black and red. It's not worth the hastle and charge appropriately.

Also I believe some people airbrush their cakes darker colors so they don't have to buy a special color but that only works if you have an airbrush machine

Yup, I am with the others. For red and black it is worth buying it. Way less time and your hands don't look like you have butchered something when you are done!

I agree...I buy black and red!! I'm done stressing about making the color deep enough. Then all that dye changes the fondant texture too.