I have a 35mm negative that needs extensive manipulation to print. I was going to make a 4x5 positive from it, do some retouching on that, and contact print that positive to a working 4x5 negative. I was wondering what material to use both for more subtle retouching, and for completely erasing an element. I have a bright light pole standing against a black background, and I want to completely erase it. This amounts to basically painting the item out on the interpositve...I've thought about using black fingernail polish. What about red crayon? I could almost just use electrical tape, but I don't want the added thickness in the sandwich. For more subtle retouching in the highlights, does pencil work ok?