My contractor used white silicon caulk on my quartz tri-colored brand new bathroom countertop, smearing it in a wide swath on all the seams where backsplash meets the countertop. My quartz countertop is black, brown, and tan spots on a vanilla background. This pure white caulk looks hideous. Want to know how to remove the caulk and does it even need caulking since the backsplash was sealed underneath where it sits on the countertop - there are no gaps. The new bathroom sink was caulked with a clear silicon that doesn't show. Shouldn't the quartz seams look nearly invisible? The countertop has only been in a week. I don't want to scratch the quartz. What can I do to take off the caulk and remedy this?
I would suggest denatured alcohol along with a very sharp chisel with no nicks in it. Drown the caulk with the alcohol and let it set for a good hour. After that gently use your chisel to slide along the base of the backsplash. Your fingernails are really good for scratching out the silicone after the alcohol has penetrating it. Once cleaned out I would purchase a clear silicone or even a translucent caulk which you can probably buy online. Home Depot will definitely have clear silicone. Cut the tip at a 45 degree angle and make the opening in the tip around 1/8 inch hole. Caulk 8 inch portions at a time and use the denatured alcohol to get it off your hands. Denatured alcohol won't hurt your quarts but you may want some gloves for your hands but it's hard to caulk with rubber gloves. Honestly I would have the contractor clean it up. To me that is unacceptable installation of your quartz top. They should know what the appropriate caulk is to use.
Once pure silicone is cured there are no cleaners or solvents, that I'm aware of (maybe an acid), to remove or dissolve it. I've had very good success removing dried silicone that had not been applied carefully by "pushing" it off the surface. With your thumb or pointer finger apply pressure on the wayward silicone smear pushing back and forth. If the bead is thin the friction that is created by your digit will start peeling it off the surface. The alternative is to very cautiously slice the sealer off with a single edged blade. Be alert, even though quartz is a fairly hard mineral a sharp edge can still nick the surface. Keep the blade angle low; 25-30 degrees and push with easy short strokes. Depending on the countertop composition, silicone is used frequently as an adhesive and a sealer. Its color is usually matched to the most prominent color of the countertop. For a neat and discreet caulk bead, blue painters tape can be placed as a protective border so that any caulking that spreads beyond the intended area will be removed with the tape.
Carefully remove the bulk of the old silicone caulk by any of the mechanical methods mentioned in the other answers; I personally prefer using a razor blade. Then apply some Goo Gone to the remaining caulk; don't try to pour it on as it is rather runny stuff. You don't need to use a lot, just make sure the entire joint line is wetted. Let the Goo Gone sit for about 15 minutes. It will not completely dissolve the residual silicone, but it will soften it to the point that you can scrub or scrape it off fairly easily. Repeat if necessary. For tubs and showers, I scrub the joint using a small piece of the gentlest Scotch-Brite (the white stuff) soaked in Goo Gone and have not noticed any objectionable abrasion marks, but be careful. A piece of paper towel and some elbow grease should also work. Make sure all of the old caulk is gone; new caulk of any kind will not adhere properly to a surface left contaminated with old cured silicone. I use isopropyl alcohol to clean off the Goo Gone and then wait until the joint is completely dry before re-caulking.