There are dark stains on my 2 year old light color granite countertops, even though I applied 2 layers of sealer* when they were brand new. They were purchased directly from a large wholesaler by a friend who is a very small contractor. The locations of the stains and a history of only infrequent small water splashes suggest that they were caused by human skin oils. How can the stains be removed, and future staining prevented? *"Stone Pro" "Ultimate Pro" "Impregnating Sealer for Dense Stone" was used ($43 a quart).
If your stain is something like oil that has made it past the sealer you may be able to “draw” it back out of the granite. You want a poultice to sit on the stain, you can buy special powders for this by I found plaster of Paris and acetone worked better.
Be sure to test in an inconspicuous spot first to make sure this will not make things look worse.
- Wipe the area clean with soap and water to remove any dirt and grime. The surface should be clean above the oil spot.
- Mix plaster of Paris with acetone in a container. Start with the plaster of Paris in the empty container and slowly add/mix in the acetone until the plaster is dissolved into a goopy paste. You don’t want it too runny but you don’t want dry chunks of plaster either.
- Put the mixture on the stain, overlap the stain by at least an inch all around and pile it up a bit. Don’t spread it out too thin, I usually have it at least a ¼ inch high.
- Cover with plastic wrap and tape down the edges with masking tape.
- After 12 or 24 hours remove everything (the plaster of Paris mixture, plastic wrap, and tape). The stain should be lighter or gone completely. If it is lighter but still visible repeat the procedure.
This process worked well for me on my white granite that was super porous and I mistakenly used plumbers putty to seal the kitchen faucet. I was horrified to see an oil stain the next day. I removed the putty and let it dry out but the stain persisted. Using the process above I got it removed.
Last point, you likely will just have to seal this granite a lot. You have enough sealant on it when water beads up on it, once it stops you need more sealer. It may be 1 or 2 years later or even sooner. The stone will tell you when you need to reapply, not a calendar.