Repairing Limestone Etching and Scratching

Repairing Limestone Etching and Scratching

Limestone is one of the most prevalent natural stones in the United States and is gaining popularity in design since it requires little maintenance, offers excellent wear-ability and is quite versatile.  It is a popular and excellent choice for floors, shower walls, mantels, outdoor tabletops and kitchen countertops. It is quarried in nine states, with Wisconsin and Indiana producing the most.

While hardy, beautiful and elegant limestone is a calcite based stone, making it vulnerable to etching, just like marble. (Remember, marble is a limestone; however limestone is not a marble). Limestone is also a soft stone making it susceptible to scratches.

Etching

Etching is the most common natural stone problem, especially with limestone. Any acidic substance—tomatoes, wine, soda, vinegar—that touches your limestone will most likely leave a white-ish, dull mark that resembles a water-glass ring on a table. If the etch is really bad, you can actually feel it with your fingers.

The Solution:  For light etching on polished limestone you can remove the etching yourself with a mild etch remover paste. For more severe etching or etching on honed (non-reflective) surfaces, it is recommended that you call a stone restoration professional.

Scratches

Scratches will occur in limestone because it is such a soft stone. Knives —anything sharp for that matter—and abrasive cleaners can easily scratch your precious limestone.

The Solution: For light scratches in darker limestone, blot mineral oil into the scratch. If your stone is lightly colored, honed or polished, use super fine sandpaper, working your way up to finer and finer grits until the scratch disappears. Deeper and larger scratches should be buffed out by a professional.

 

This is one of a series of articles written and published  on behalf of Stone and Tile PRO Partners.

I’m sorry, I think you mythunderstood me

It’s kind of funny what people who should know better will say about common stone failures or issues. Over the past several years, we have heard many stories about the reasons stone will fail, turn color, fade, and so on. Many are comical and most are just plain false. Here’s a sampling you may enjoy…

A Warped Sense of Humor

Many seasoned installers who have tried to install green marble tiles with ordinary thin set or other water-based setting materials have experienced warping problems. Here are two ways we’ve heard them explained.

1. Myth: “Green Marble will warp because it contains living plant material. As water is added to the marble, the plants start to grow and this makes the marble warp.” We nearly fell over laughing, but he wasn’t kidding. He really thought this was the reason.

2. Myth: “Green Marble will curl on the edges because the installer did not put enough setting mortar on the edges. The green marble will have a tendency to lift off the floor where there is no mortar and hence will curl.” While not quite as outrageous as the first explanation, it is still just as wrong.
Truth: The real reason green marble warps is a condition known as hysterisis. Green marble is very sensitive to moisture. When water enters the stone, it causes the marble to release any internal stress, thus causing it to warp.

Home Sweet What?

3. Myth: “Your stone floor needs to be homed!”
Truth: No, this is not a spelling mistake – the word used was “homed.” We have run into several sales people who have called the honing process “homing.” Maybe they also worked with pigeons, but we’ve never heard of homing a floor. The proper term, of course, is “HONE,” which means to abrade a stone.

“Plop, Plop, Fizz, Fizz…”

4. Myth: “Your stone floor has an effervescence problem.”
Truth: The key word here is “effervescence.” Let’s clear this up right now. Efflorescence is the deposit of soluble salts on the surface of the stone that is caused by water that carries the salts from the setting bed of the stone to the surface; it is often deposited as a white powder-like residue on the surface of the stone. Effervescence is what happens when something fizzes. A good example is when you drop a tablet of Alka-Seltzer into a glass of water. The fizzing is referred to as “effervescence.” We’ve never seen a stone effervesce unless someone was pouring acid on it!

5. Myth: “Sealing your stone will help with your efflorescence problem.” Truth: We’ve heard so-called experts instruct people with an efflorescence problem to seal the stone as a remedy. This is wrong. Sealing will only block or reduce the pore size of the stone, which will not only cause more efflorescence, but it could also cause spalling, which is when the stone flakes at the surface.

Are You Cracked?

6. Myth: “That’s not a crack, it’s a fissure!”
Truth: Many fabricators will try to blame cracks that occur in stone installations on natural fissures that occur in the stone. Sometimes they are right and sometimes they are wrong. If you look up the word “fissure” in the dictionary, guess what? A fissure is a crack. The distinction they are trying to make is between fissures, which are naturally occurring as part of the formation of the stone and cracks (more appropriately called “breaks”) caused by external forces on the stone. Of course, the most likely place for a break to occur is on a natural fissure. Consequently, definitions need to be clarified and the stone needs to be examined carefully to determine if natural fissures are at risk of becoming breaks during normal usage.

Would You Like Some Salad With That?

7. Myth: “To remove oil from stone, saturating it with water will force the oil out.” Truth: Since it is true that oil floats on water, you would think this makes sense. But trust us, it doesn’t work. The oil is trapped in the pores of the stone and no amount of water is going to force it out. The best way to remove oil from stone is with a poultice and a degreasing chemical. For specifics and poulticing instructions, see https://surfacecarepros.com/stain-management-app/ .

8. Myth: “Just use some vinegar and water to clean your marble or limestone.” Truth: Generally folks in the stone business know better, however this is often recommended by tile installers. Don’t do it! Vinegar is an acid and will etch calcium-based stone. Marble and limestone are generally the most susceptible, but some types of granite will also be damaged by vinegar.

Stones Can Be So Vein!

9. Myth: “If it’s got veins, it’s marble.” Truth: This is a fib we hear all the time. Many people in the industry believe that if a stone has veins, it must be marble. This is totally false. Veins can also be found in granite and limestone.

You Make Me Sick!

10. Myth: “Granite countertops harbor bacteria and emit harmful radon gas.” Truth: This is absolutely FALSE! NIOSH and the CDC have no reports of granite or any other stone used as a countertop being unsafe. If stone were unsafe or unsanitary, why would it be used in food laboratories or sold as cutting boards? There has been no known proof of any illness caused by using stone as a countertop. And as for the rumors that granite contains harmful radon gas — there is so little radon in granite that you would have to live to be 10,000 years old for it to have an ill effect on you. There is likely more radon coming from the ground and the concrete that your house is built on.

What You Need to Know About Caring for Soapstone

Do you have or are you considering soapstone? Here are some tips for caring for soapstone and keeping it beautiful.

For New Installations

If your soapstone has just been installed, perform weekly oiling with a food grade mineral oil or enhancer made for soapstone for the first month, and then twice a month for the next three months. After the fourth month, you should only need to oil once a month or less. As the oil evaporates, the stone will lighten, telling you that it is time for another oiling.

To Enhance or Not…. This is the Question

Versatility of finish is one of the great pluses of soapstone. Some homeowners love the natural, untreated soft-gray look, while others prefer to color enhance it to bring out the deeper colors. The choice is yours.

Virtually Stain Proof

Alkalis and acids found in many foods and drinks are not likely to stain the dense and inert surface of soapstone (which is why it is so popular in labs and science classrooms). Any staining that occurs can be quickly and easily remedied with scrubbing or sanding.

Scratches

Soapstone is a very soft stone and scratches will occur. Light scratches will disappear with a direct dab of FDA approved food-grade mineral oil or soapstone enhancer. To permanently remove a deeper scratch, apply medium pressure to the scratched area with an 80 grit sanding sponge.

Apply a light coat of FDA approved food-grade mineral oil or soapstone enhancer to the sanded area. The mineral oil application should be repeated 2-3 times over a 2-3 day period until the sanded area matches the coloration of the rest of the stone. The enhancer should be applied twice with the second application about 24 hours after the first.

Returned to Its Former Beauty…

Even after 100 years of hard use, soapstone can be re-finished to a new state as though it had just been installed. Give us a call if you need any help. As a stone care professional we can expertly perform the services needed to repair or restore your soapstone.

See the full article, Stone Showcase: Soapstone in the Spring 2014 issue of Stone Advisory Magazine.

This is one of a series of articles written and published  on behalf of Stone and Tile PRO Partners.

Testing Stone For Kitchen Countertop Usability -The Lemon Juice and Oil Test

It is time to select your granite for your kitchen countertops. What should you look for? Two things: Absorbency and acid sensitivity. You do NOT want a stone that is too absorbent, and you do NOT want a stone that is mixed with calcite (the main component of marble and limestone).

The Lemon Juice and Oil Test will help you determine the suitability of any stone you are considering.

Collect a sample of any stone you are considering. Line them up on a table or countertop, dust them thoroughly, then spill a few drops of lemon juice and cooking oil on each one of them. If you notice that where the juice and the oil hit the stone, its surface turns dark im-mediately, eliminate them as an appropriate candidate.

If you notice that the juice and the oil take a little time to get absorbed (a half a minute or better), then you have a stone whose absorbency can be effectively controlled with a good-quality impregnator.

If you finally notice that some samples will not absorb anything within, say, half an hour or so, then you may have a winner. That stone will not even need to be sealed.

Now, how to eliminate the word ‘may’ from the equation? The answer in another question: Why use lemon juice instead of, say plain water? as you’re not just look-ing to determine the absorbency of the considering, also want to determine that your samples are 100% silicate rocks to some stones—which may be traded as granite of calcite. If there’s even a little calcite in the stone, it will (citric acid) and, when you wipe your spills dry, you will notice a dull spot of the same shape of the lemon drops. In such case, once again, these stones would not be appropriate for a kitchen countertop. If instead it’s still nice and shiny under where the drops were, then you eliminated the ‘may’ factor!