Basic Guidelines for “Two-Step” Restoration Procedure of Marble Shower Stalls (Part 3)
The following guidelines are designed for serpentine and ophicalcite marbles (green marbles, Rosso Levanto, Verde Alpi, etc).
1st and 2nd Step - Honing and Polishing
Use only 4” or 5” diameter good-quality dry diamond pads on a flexible backer pad. Not only will the logic behind the use of dry diamond pads apply now, but in the case of these types of marbles, good quality phenolic resin-based diamond pads, when used properly, will actually polish and give you a finish as close to factory as possible.
Remember - every time you change grit (going higher), start by applying a certain pressure (keep your right-angle grinder/polisher titled approximately at 45 degree angle in relation to your working surface; that’s why it is so important that the backer pad be flexible) and then finish light and flat. As you change grit, increase the RPMs of the machine. Starting from the 400 grit, you will operate at approximately 2500 RPM. The final couple of polishing cuts should be done at 3000 RPM.The method of phenolic diamond pads dry polishing will work with some other marbles too- such as Emperador and Botticino for instance. Just test!
If the customer won’t have the faucets and other encumbrances removed, your best bet to reach those areas is to wrap your index and medium finger with a piece of slightly damp terry cloth, dip it in the container of dry-polishing powder, and then rub it over those areas. Repeat if necessary, but don’t overdo. The customer was already advised not to expect anything stellar on those particular spots. Dry- polishing powders won’t work well on green marble under circumstances like this, but it will remove any possible mineral deposits sitting on top of the stone. With green and darker marbles, if you don’t get the depth of color associated with a good polish, you can finish the job with the application of a good-quality stone color enhancer. Applying a good-quality stone polish at the end of the job, after the final clean up, will give a nice (and much appreciated) smoothness and sparkle to the whole project!
It is impossible to actually polish triangular soap-holders that might be found in the corners of marble shower stalls. Typically, nobody can actually see if those small pieces of tiles are polished or not, since there is not visual angle to detect the finish. Unfortunately, however, in most cases you will find that there will be a heavy buildup of soap scum and mineral deposits, and therefore they will be rough to the touch. The best course of action is to remove the worst of whatever is on top of the stone with a razor blade and then finish the “cleaning” by hand with a 60 grit piece of sandpaper. You will follow with a couple of finer grits of sandpaper, until the surface is nice and smooth to the touch. Finish the job with an application of a good-quality stone color enhancer to produce the depth of color that the stone will be lacking because it will not actually be polished.
End of Part 3
For more detailed information and step by step instruction, purchase our Natural Stone Maintenance Book or consider attending one of our Stone Restoration Training Classes in Wilson, NC.