Thinning dark colors

[dannyplug1]

I was painting plugs last night. I was trying to paint the back of my plugs with a dark brown. No matter what I did the color was too black. Is there a way to thin the paint with out loosing the color? I know that if you have a black and you add white to it will turn gray provided you don't have too much black in which case it will remain dark. If you thin out the black and it turns gray will it turn black if you put enough light coats of gray? Guess what I really want to know is how do you thin the Createx paints when you want to retain the color but want a very light almost translucent look on the plug. another question how would you thin an orange to make light translucent coats and retain the same color you started with? Thanks charlie