Katharine is right. You do get a stain. A layer of plain gum on top of everything will give you a tan color on your print. If you want an aged look, I think it would work well. On my website I have two identical images from my Italy (Italy #31) portfolio. One has a top coat of plain gum. You can see it put a tan-ish tint on it.
Steve
www.scdowellphoto.com