I love white letters and using them as the negative space with water colors. So i bought a jar of masking fluid to play around with. Unfortunately it went on horribly, drying within seconds and pulling up when ever i tried to fix areas. On a whim i tried Mod Podge, pretty much just because i had it on my desk. Wonder of wonders, it worked way better! It didnt peel off like the masking fluid but since it dried clear it wasnt a problem.
I tried it over pencil to see how visible the lines would be but they were totally visible.
So i lightly erased the words, leaving just enough visible to make sure i wrote the right thing.