Sungloss Marble Restoration Company’s had some experience over the last 20 years with various issues that come with owning limestone, granite, sandstone, marble, terrazzo, and other natural stone. Of all the wide assortment of maintenance and restoration issues we find solutions for, oxidation is one of our most despised. Natural stone, especially white marble, over time has the potential to yellow or discolor because of oxidation. Homeowners, developers, construction companies, and commercial building owners, and anyone who enjoys natural stone can attest to the blight of oxidation.
So, what causes it? In a word, iron. Iron and moisture, that is. In the case of white marble turning yellow, there could be many causes, a few of which we wrote about in this blog in the past. Oxidation is responsible for yellow-brown stains that look like they are coming from the inside-out. Within marble is a naturally occurring percentage of iron, and if the stone is exposed to high quantities of water (a flood or leak) or continuous moisture (as inside a shower), the iron will literally rust. Or, if you are unlucky enough to have a high iron content in your service water, the act of cleaning the stone could deposit small particles of iron in the stone which eventually could exacerbate the oxidation process.
Even the best of our Restoration Technicians cringe when they hear ‘oxidation’ because they know that some stone with significant rust spots cannot be fully restored. However, there is hope in trying multiple techniques, sometimes time-consuming, which could include a poultice that is applied for about a week. That, along with some other tricks of the trade might result in a significant improvement.
The best prophylactic is to stay on top of having the marble sealed with a quality stone sealer; we recommend annually or possibly bi-annually in ‘high abuse’ areas, like a shower or vanity. Sungloss Marble Restoration Company mostly uses water-based sealers, which are better for the environment. Also, proper cleaning practices should be followed: the short version is to use a mild rinseless stone soap and appropriate applicator (think soft and/or gentle)…the long version can be found here. And, a nice article about yellow staining here.