I love the variety of picture frames out there as anyone who has visited my home can attest, but I do not like getting the bar code stickers that are always stuck on the glass. There are several products on the market to de-stick such things, but none of them seem to work very well for me. What works the best for me is plain old vegetable oil and the gentle scrubbing of an old toothbrush. After the sticker and its gluey remnants have come loose, rinse the glass in water with a small quantity of dish soap.
