How to remove granite discolorations caused by foaming tub cleaner?

Q. Hi. A foaming tub cleaner was knocked over on my granite sink counter, and I have no idea how to fix the discolorations it caused. I see all kinds of fixes for foods and oils online but none for cleaners. Please help, asap!!!

A. When a tub cleaner spills on granite, the issue is usually chemical damage, not a typical "stain." Not all discolorations on stone are stains. A true stain is absorbed into the stone and appears darker, while lighter or dull spots are usually surface damage caused by acidic or alkaline cleaners. These marks are not stains and require refinishing, not stain removal.

Here’s how to understand what happened. Most tub cleaners are acidic or alkaline and contain surfactants and solvents. Granite is fairly durable, but these cleaners can etch the surface, strip the sealer, or both.

A quick way to diagnose the discoloration: If the area looks lighter, dull, cloudy, or uneven and doesn’t darken when wet, it’s likely etching (surface damage). If it looks blotchy and darkens when wet, the cleaner probably removed or damaged the sealer, allowing moisture to absorb unevenly.

Unfortunately, etching is not something that can be cleaned away. The stone itself has been microscopically altered, which changes how light reflects. No DIY methods will help. The surface has to be mechanically refinished, that is, polished or honed, to restore a uniform appearance. This is what stone restoration contractors do. To find a vetted PRO in your area, visit www.surfacecarepros.com and click on Find a PRO.

If the problem is sealer damage rather than etching, there’s a chance it can improve with reapplication of sealer. Applying a penetrating granite sealer may even out the appearance. Always test in a small, inconspicuous area first. (A PRO can select and properly apply the most appropriate sealer.)

Don’t use vinegar, ammonia, or bleach. Don’t scrub aggressively or use abrasive pads.

aABOUT THE AUTHOR Fred Hueston is the Chief Technical Director at SurfaceCarePROS.com and Director at StoneForensics.com. He is also the author of Stone and Tile Restoration: The Manual, a comprehensive online manual for stone and tile restoration contractors. [Learn more about Fred.]