QUESTION
I have a personal question for you. We are re-doing our backyard, and the pool coping we picked out is a Indian black limestone coping, see the attached photo. We were told by the installer we should not seal it, even with a penetrating sealer because it causes other issues like visible scratching, flaking, etc.Can you give me your opinion on if we should seal it, and if you think it should be sealed, what product should we be using?
ANSWER
Always take what the contractor says with a grain of salt and make sure there is documents backing it up. Don’t assume they are doing things correctly and read the directions that they likely don’t to make sure they are using the products correctly. You have to be the QC Guy.Limestone falls under ASTM C568. There are 3 classifications: Low Density, Medium Density and High Density Limestone with different physical properties. Normally you only want to use medium or high density limestones on the exterior in warmer CA areas.
Whether the limestone performs well or not depends on the application and how it is installed. It is when the stone is subjected to excessive moisture that it ends up spalling. You have to consider drainage and moisture control in the installation design. Best is to bond over concrete over a liquid applied waterproof membrane. So the installer should be installing the coping over a concrete pool bond beam. That should be waterproofed with a liquid applied product like Laticrete Hydro Ban or Custom RedGard and then the tile bonded to the membrane with an ANSI A118.4 or .15 thinset mortar. They should achieve full thinset contact between the membrane and the back of the stone. No voids. The front joint below the coping in the pool should be caulked with a sealant like Custom 100% Silicone that is suitable for swimming pool. The coping joint on the top back should be filled with an ASTM C920 traffic grade sealant like Sika Flex + Self Leveling Sealant that you can buy at Home Depot in different colors. This bonds tenaciously and makes the joint water tight, and lasts a long time if installed correctly.
The sealers will not cause a problem if they are selected and used correctly. Sealers are temporary and wear. They do not waterproof the tile. There are different types of sealers. Surface sealers can peal. Penetrating sealers if applied correctly will not peal. You do have to reapply every year more or less depending on the look or performance that you want to maintain. Some sealers are enhancers to give a wet look. Only use the penetrating type. Miracle 511 Seal and Enhancer sealer or Dry Treat Color Enhancing Sealers. Or they both have penetrating sealers where sealing it doesn’t change the appearance of the stone that much.
Good luck!
We just installed a pool with a limestone deck and coping. They were the same color at first, but the coping has changed and darkened/yellowed a shade different. They cleaned and sealed both the deck and coping with the same product. The decking was installed over concrete. I am looking for the best cleaner and sealer to keep the stone from staining and keep the white color. The installer used Mapei- Heavy Duty Stone Tile and grout cleaner: High alkaline cleaner and degreaser. The sealer was Miracle- Sealants- tile stone and grout sealer.
Should I use these again, or do you believe these caused the coping dis coloration?
At this point, regardless of these products already used, can you recommend the best product for us moving forward to keep the color?
A second question, how can we tell whether our limestone deck is honed, etched and the level of density- low, medium ir high? All I got from the builder was a color named Coral Beige limestone,, 1 1/4″ (3cm) for the decking and 2″ for the coping by http://www.Stonesolution.com.
Thank you inadvance for any suggestions or data.
The only way to determine the limestone classification relative to its physical properties is to perform laboratory testing on the stone.
The discoloration of the limestone coping might have more to do with how it was installed. If the limestone coping is being subjected to excessive moisture. The coping is installed over the pool bond beam and it is recommended to waterproof the top of the bond beam first and then caulk on both sides of coping at the water line and at the transition between the coping stone and the deck stone.
Sealers are only temporary and depending on the climatic and other conditions it is subjected to they wear away. Sealers are meant to make the surface of the the stone water resistant. They don’t make the stone waterproof. You need to clean the stone to the condition you want before you seal it and trap in any undesirable conditions. The source of the staining might be coming up from beneath the stone. So even if you seal the surface it might not prevent the discoloration. To determine how best to remediate your problem requires performing a forensic investigation by an experience and qualified stone expert.
Dear Donato,
Congratulation for the great information on your website! I found it through an online search for expert advice.
What’s the best way to protect a limestone kitchen floor?
I live in Portugal and I bought a house with a local limestone called Moleanos (https://www.moleanos.com/) on floors and bathrooms countertops, external wall and banisters
The stones are very porous and stain easily, plus they are 20 years old and started to feel porous and dust off at the touch.
A local contractor who’s doing the polishing proposed to use an epoxy protection that he said he ships from the US but won’t disclose the name.. ( it’s an expensive product 800 euros for 16 m2)
what’s the recommended treatment to protect them from water and stains? Are you familiar with epoxy coating? Is it something that you would recommend?
In case would you ship an alternative product to Portugal?
Thank you and best
You should never coat a natural stone with an epoxy coating or any surface non-breathable coating. There are penetrating sealers for natural stone like Dry Treat, Prosoco or Miracle Sealants that penetrates into the stone but still allows it to breath.
Sealers have to be reapplied as they do wear depending on the conditions they are subjected to. If you put a small drop of water on the surface of the stone and it beads up and doesn’t leave a wet spot after you wipe it up then it is working. Otherwise it may need to have the sealer reapplied. You want to use the type of sealer that does not require stripping it before reapplying.
Whatever you choose to use, be sure to test it on an unused tile to make sure you are satisfied with the results before applying it to your entire floor.