I had despaired of ever getting the aluminum marks off of my Kohl cast iron, porcelain coated sink...it's white. I've used Comet, bleach, scrub pads, you name it. When I bought my Stainless skillets and pots I bought some Bar Keepers Friend to keep them nice and shiny. I'd just finished cleaning my skillet and had the cleaner in my hand and thought, "Why not?" I sprinkled a little on a mark, grabbed my dish cloth..swish, swish, the stain was gone! Now my white sink is sparkling white again...try it, you'll like it!
Don't wait too long to tell someone you love them.
Billy
Billy