Does Quartz Stain? Why Quartz Marks and When to Seal It

What that mark probably is

• Sticky or cloudy patch: dried soap, grease or cleaner residue. Comes off.
• White ring by the faucet: hard-water mineral film. Comes off with the right cleaner.
• Yellow or dull ring where a pan sat: heat damage to the resin. Does not wash off.
• Dull spot from lemon, vinegar or cleaner: an etch, chemical damage to the resin. More common on lower-cost quartz.
• Dull, rough spot after scrubbing: finish worn by an abrasive pad or strong chemical. Needs professional work.
• Color that went in: a true stain. Coffee, wine, turmeric or dye that got into weak resin.

When sealing quartz makes sense

The old advice is that quartz never needs sealing. That holds for well-made slabs. In homes around Manteca, we're finding more quartz that stains, etches and dulls, often lower-cost slabs whose resin doesn't hold up. On those counters, a sealer made for quartz gives spills a barrier to sit on instead of the resin.

Two cautions. A regular natural-stone sealer is the wrong product: it has nothing to soak into and leaves a streaky film. And check your quartz warranty first, since some makers exclude aftermarket treatments. Not sure your counter is quartz? Here's how to tell.