How to Differentiate Between Staining and Etching

Two of the most common forms of damage to natural-stone countertops comes in the form of staining and etching. While stains are the result of a substance penetrating the pores of the stone and leaving its residue, etching is actually a chemical burn on the structure itself. Etching is often mistaken for a water stain, but is actually physical damage that typically requires professional help to fix, while most stains can be lifted on your own. Both types of damage can be done by the same liquids, like coffee or red wine as two common examples. Also, both can be mitigated by maintaining the integrity of your stone's seal (more on that later).

What is Etching?

Etching occurs when acidic chemicals eat away and dissolve the surface of your countertops. Almost every natural stone contains calcium carbonate, which is susceptible to this chemical reaction from common liquids like vinegar, red wine, citrus, coffee, common household cleaners and soda. Granite, marble and travertine are a few common building materials that are susceptible to this kind of damage. In mild cases, this chemical etching looks just like water or other clear liquid stains that you might see from someone not using a coaster, or just a general dulling of the surface sheen. The longer your stone is exposed to these chemicals, the worse the damage will become.

Common Causes of Etching:

As mentioned, acidic foods and beverages are a common culprit, but this also extends to many household cleaning products, like vinegar, bleach and ammonia. The use of cutting boards and other food prep surfaces will go a long way toward protecting your countertops, but etching often occurs due to accidental spillage as well. This is why it's important to always wipe up a spill as soon as it happens, even if you're in the middle of preparing a meal. Using coasters, trivets or serving trays will help to prevent these issues as well. Even if a spill doesn't etch your stone, it can damage the protective seal, which opens you up to difficult stains in the future if not corrected.

What Is Staining?

Since stone is a naturally porous material, if left unsealed, liquids can penetrate the pores of the stone and leave a stain beneath the surface. Unlike etches, stains do not affect the finish of the stone, only the coloring and appearance. Unless the stone is already severely damaged, most stains can be lifted with the right solution and technique (which you can find below). A stain is also a clear sign that your stone needs to be resealed, as a good stone seal should prevent liquids from seeping beneath the surface in the first place.

Stains and Etches Often Go Together:

Oftentimes, an etch mark and stain will occur at the same time. This is common when something like tomato sauce or coffee is spilled onto the countertop. The acidity of the liquid etches the stone -- which in turn makes it more susceptible to staining. If not immediately cleaned up, the stone will absorb the liquid, leaving a stain.

How to Treat Stains Versus Etches:

Cooking oil stains are very common on stone countertops. To lift these stains, mix baking soda and acetone to create a paste to the consistency of pancake batter over the stain. Allow the paste to sit for 24 hours, then rinse the mixture away with water. Repeat if necessary; some stains may require two or three attempts. Be sure to re-seal the stone once complete.

For organic stains, mix one-part laundry bleach with one-part water and spray it onto the surface (the mixed solution won’t harm stone). Scrub with a safe-on-stone scrub sponge, such as the Granite Gold Scrub Sponge® or a blue Scotch-Brite pad (other pads are too harsh on stone), or nylon brush (like grout brush we include with Granite Gold Grout Cleaner®). Let it sit for 15 minutes and rinse with water.

Alternatively, pour or spray 3 percent or 4 percent hydrogen peroxide on the stained area and agitated with a Granite Gold Scrub Sponge® or Granite Gold Grout Brush® and allow to sit for 24 hours, then rinse with water and immediately reseal the stone.

For more stubborn stains, place a plain white paper towel over the stain and pour either solution (one-part laundry bleach with one-part water or 3 percent or 4 percent hydrogen peroxide) onto the paper towel to thoroughly saturate the paper towel. Allow this to sit for 24 hours; remove paper towel and rinse area with water and repeat if needed.

Note: DO NOT MIX BLEACH WITH HYDROGEN PEROXIDE. Treating etched stone is not as simple. Since etching is physical damage to the stone as opposed to a liquid or pigment trapped beneath the surface, refinishing of the stone may be required to regain the sheen the surface once had.

Preventing Stains and Etch Marks:

Cleaning spills with a specially formulated natural-stone-safe cleaner is an important step in preventing either of these issues. As opposed to most household cleaners, a product like Granite Gold Daily Cleaner® is pH neutral and completely streak free. This not only helps prevent damage to your stone's seal, but also prevents the etching and staining issues outlined above.

How do you know when it's time to reseal?

You can check the integrity of your seal at any time with the water test. This is done by pouring a small spot of water (about 3 inches in diameter) onto the surface of your stone in various locations and letting it sit for 30 minutes before wiping away. If a dark spot becomes visible in those locations, water is penetrating the surface of your stone and needs to be resealed. In general, it's recommended to seal your stone every 6-12 months, but heavily used areas and spots that have been thoroughly scrubbed or cleaned with something like bleach might require sealing more often than that. You can find more info in our sealing guide here.

Looking to read up on more natural stone care tips? Check out all the helpful resources we have available here, or give our stone care experts a call at 1-800-475-STONE. Also, to make sure you get the most out of your investment, be sure to check out our full line of stone care products!