What I used to color the security envelopes and I thought I should probably say that it was not your usual paint etc. What I used is Meltonian Cream Shoe Polish. It does some lovely things to paper because the wax fills in the paper pores so it makes thicker paper feel a lot like leather. If it is buffed nicely it does not release color and it smells good. It comes in a nice array of colors also and is fairly transparent . I have absolutely no link to these guys, I ended up with some really scuffed red clogs and when I went to my local shoe repair shop, this was the only shoe polish they had in close to the right color and it was inexpensive also! One day it was lying out when I was playing with coloring paper and one thing led to another and there we are. I now have 6 colors and use it a lot on the covers of my quickly sewn up booklets..