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Understanding Etch Removal

If you haven't ever dealt with an etch before, it can bring a number of surprises you weren't expecting. Some aspects that catch people off guard are 1) knowing what an etch is, 2) grasping what the treatment involves, and 3) understanding what the treatment actually does to "fix" the problem. In this article, we are going to explain each of those as we help you with understanding etch removal.

What is Etching?

After cleaning up on the heels of a dinner party, a get-together, or some other function in your home, you notice that the surface of your beautiful marble table, countertop, or kitchen island is not like it was before the event. As you cast your eyes across the surface, the light reveals inconsistencies in your marble's appearance. If your marble is polished, you see random dull spots in the polish. If the surface is honed the spots appear to look a little darker than the rest of the surface. You think to yourself, "oh, I missed a spot" and you go over that area once more with your mild soap and water solution or pH neutral natural stone cleaner. However, the discoloration does not go away. Try as you might to remove those spots, it does not come off. The reason often times is because the discoloration is an etch.

Etches Are Much Less Than a Stain

It is tempting to say that "etches are much more than a stain" because they are not as simple to understand, but the reality is that they are just the opposite. When a stone gets "stained", the result is that the stone takes on something that was not there before the stain occurred. Often times it is a substance that is colored - whether water-based or oil-based. You might say that a stain forms in an "additive" fashion. This is not the case with an etch. In fact, after a stone etches, there is less there than before. Why do we say that?

A Key to Understanding Etched Marble

Marble (and other natural stone like it) is referred to as a "calcareous stone". Without going into a long-winded explanation, calcareous stone is made up mainly of calcium carbonate. In the case of marble, the calcium carbonate is in the form of little crystals that make the material gleam in the light. Polishing marble enhances this feature and marble surfaces simply sparkle. The to grasping what happens when marble gets etched is to know what causes it. Calcite readily reacts with acids. The reaction neutralizes the acid, but it also destroys the calcium carbonate in the process. You probably see where we are going with this. The reaction removes the nice, shiny, calcite crystals that make the light dance across the surface of the material. So the result of an etch in a marble surface is that some of the stone is dissolved. Again, there is not as much of the stone as there was before so unlike a stain, etching is what might be called a "subtractive" process. Understanding how etching happens helps with grasping the answer to the next point.

Treating An Etch Requires Patience and Effort

Now that we have covered what happens to a stone as it is etched, it puts the treatment into perspective. After all, how do you fix a problem that occurs by actually removing part of the stone? We will get into the way the treament works in the following section but for now let's focus on two primary things you'll need to treat an etch. First and foremost, you'll need to have patience. This is because the treatment takes a reasonable amount of time to correct the stone's appearance. Second, you will need a degree of elbow grease. The process for correcting an etch takes persistent rubbing in a circular motion. Because of the nature of the treatment, it may take a while to get the appearance to a level that meets with your satisfaction. The process for treating an etch is as follows:

  1. Apply a spoonful of etch remover over the etch or "water mark".
  2. Using a rag, rub the etch remover over the blemish by hand.
  3. Continue rubbing the affected area for approximately 3 minutes.
  4. If necessary, repeat steps 1-3 until the etch is removed from the marble.
  5. Treat the restored marble with a sealer to help protect it from other stains.

How Do Etching Treatments Fix the Etch?

We have already established that an etch is caused by a loss of material that is the result of acid dissolving the calcite. So what actually happens when the etch is treated? Well the short answer is that the treatment removes more of the calcite. That's right, you read it correctly. The treatment removes more of the calcite from the stone. Notice what one woman mentioned in a 4 star review:

"The product works, however, I noticed after applied the surface seems to be not as smooth as it should. I read the directions carefully before applying."

Let's elaborate on that.

The discoloration of an etch in marble is noticeable because of the sharp contrast between the look of the affected area being right next to the part of the stone that was not affected by the acid. Treating an etch involves working on the stone with and acid that is not as drastic as the acid(s) that cause(es) the stone to etch. By gradually removing the calcite that is in the affected area and even some of the area around the spot, the process has the effect of "evening out" the appearance of the stone. Etch remover ever so slightly takes away the shiny crystals so that the contrast is no longer as noticeable. The process is similar to the way you blend paint on a wall that is just a little different color than the original. By blending the two differing surfaces, the contrast is effectively removed. However, to the discerning eye, the missing material that used to be there that was dissolved when the etch happened can be seen.

Can Etching Be Completely Removed From Stone?

Yes, an etch can be completely removed from stone. However, it will mean that a restoration professional will need to either take the stone to his equipment or bring his equipment to the stone and re-polish the area and perhaps the whole surface to even out the spot that was etched. It is not possible to add stone back where it was dissolved. Restoration by polishing the surface makes it looks just like new, but that solution is much more costly than treating the area yourself with an etch remover.

Well there you have it. Our hope is that your understanding etch removal has been increased and that you now appreciate the patience and effort that will go into getting the stone looking as close to the way it looked after being installed. We hope you will not have too many occurrences of removing etches, but now that you know how it works, you'll know what to expect.