Regardless of the degree of care exercised during construction, sometimes accidents happen. The protection of your cast stone fireplace mantel are of upmost importance when you are dealing with so many different trades during the construction of a home, especially when it comes to surfaces that require stain. For instance, perhaps when the hard wood flooring is being stained, some of the stain seeped onto the cast stone product that has recently purchased.

It is not only devastating for the homeowners, but can become a costly and time consuming expense to correct. DeVinci’s fireplace mantels and range hoods are cast out of GFRC (glass fiber reinforced concrete) and although this material may be more dense than typical concrete, it is still a porous material. So, when a dark pigment, like wood stain, comes into contact with our cast stone products, there may be more than just a surface stain that will need to be corrected. Although, most stains can be fixed on our products, it can be a slow process.

The most common stains due to construction are dirt and mortar. Dirt can be easily removed by scrubbing with a mild detergent and water. Mortar stains and residue that are left from installation will require use of a masonry cleaner. We recommend “Sure Klean Lime Solvent 101” by Prosoco Products, mixed 6 parts water to 1 part Lime Solvent solution.

Please take the necessary steps to protect surrounding areas that may come in contact with the cleaner. Soak the stone with water prior to washing with any acidic cleaning solution to prevent surface burning. Insure that lower stones are frequently drenched with water because as solution is rinsing down the stone it can gather strength when reapplied.

Using a soft bristle brush, water, and a diluted masonry cleaner will allow the stone’s surface to be cleaned without being etched. Smaller brushes such as a toothbrush or similar may be required to clean inside corners or detailed areas of the surround.

Allowing the cleaner to dry on the surface may result in stains and residue. Using fresh water, thoroughly rinse the stone’s surface to remove any chemical residue or free sand immediately after cleaning and before it is allowed to dry. Do not allow the cleaner to remain on the grout joints any longer than is absolutely necessary, as they are much more vulnerable to discoloration and deterioration when exposed to acid solutions. 

If the surround has stubborn stains that are not affected by recommended solution, contact our office for assistance. When unusual stains are encountered, the same procedures which are recommended to clean concrete, will typically clean cast stone. However, the most important step to stain removal is identifying the stain and its cause. There are degreasers and paint removers readily available for you to use, but any treatment should be tested on a small inconspicuous area prior to cleaning the main unit. We suggest testing any sealant, cleaner, stain, or remover on the samples we provided prior to your mantel order.

The best way to prevent any of the issues mentioned above is to seal your surround. This can be done 30 days after installation, which allows the mortar joints enough time to completely cure. It is not required to seal your mantel, however, we do recommend a matte finish sealer made especially for porous surfaces, such as cast stone. Prosoco Sure Klean Natural Stone Treatment WB Plus is a water-based solution developed to provide long lasting penetrating protection without altering the stone’s natural appearance. Again, please wait approximately thirty (30) days after installation, to allow mortar to cure, before sealing your mantel. It is also recommended that the sealer be tested in a small, out of the way, area before applying to the entire mantel. If you have mortar residue on the face of the cast stone, it should be cleaned and allowed to dry before the sealing process is started.

If your surround has been sealed, and you still need a cleaner, mild soap and water should take care of any stains you have. If this is not the case, please call our office and provide photos along with any information you have about the stain. This will allow our representatives to evaluate the situation in order to help you get your surround back to looking brand new.

Although sealing your entire mantel is suggested, just sealing the hearth to protect from floor finishing is an option too. As mentioned before, when sealing make sure to test it on an area that won’t be seen. Some sealants can change color of the mantel or leave a gloss-like sheen, so we only recommend applying one coat of a sealant to your cast stone surround and allowing 24 hours before inspecting and retesting another small area to see if another coat is necessary. You may try to test the sealant with a few drops of water to see how the cast stone absorbs the water. If all the water has been absorbed within a few hours, you may need to start looking into applying another coat, however, if the water stays on the surface for longer than a few hours, the single coat should be adequate.

If you’d rather not seal your mantel, you may find that simply taping your hearth edge may not be enough to keep stain off your cast stone product, as the photo above shows. Another recommendation would be to place plastic down before taping, that way there is an additional barrier between the seeping stain and your beautiful cast stone.


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