Page 17 - Demo

Slippery Rock Gazette
October 2024 | 17
Stone Restoration and
Stone Restoration and
Maintenance Corner
Maintenance Corner
Handling New and Difficult to Polish Stones
ASa stone restoration and mainte- nance contractor, you run across many types of stones, especially in 2024. There are new stones that are being used as building materials, more so than ever before. More and more exotic stones are also being used, and in many cases have their own set of issues. Used to be, pol- ishing rock was pretty straight forward; there were a few different types of marble, granite, travertine, limestone, and slate. Of course, there were also the sandstones and flagstones, terrazzo, and few others, but
this was the norm.
Nowadays, it is not uncommon to run into onyx, alabaster, jade, more and more epoxy terrazzo, and of course, the dreaded quartzite. There are so many exotic mar- bles and granites that I’ve only seen in the last few years, and I’ve been doing this for about 50 years now. There are those who want the most ornate stone they can find, just because it’s not common and no one else on their street has it.
Now, with all these exotic stones in bril- liant colors in the marketplace, they obvi- ously have different mineral content, even though they may be classified as marble or limestone or granite. The different min- erals are what make all the pretty colors and veins. Of course, most are still calci- um-based or quartz-based.
Geologically speaking, there are only a few true marbles and the same is true for granite, as well. However, for our pur- poses, and commercially speaking, we group most of the metamorphic limestones as marble and the metamorphic granites as, you guessed it, granites. These later stones are actually gneiss. Gneisses are usually the granites with lots of movement, which some mistake for veining.
For example, black granites are not true granites at all. They are basalt, anorthosite, or gabbro. Commercially, we call them black granites. Pink Tennessee marble is not a true marble, it is a metamorphic lime- stone, and the same is true for many stones that we label marble. Carrera marble is an example of a true marble.
Onyx is another example of a calcare- ous stone, like marble and limestone. So is Alabaster. These stones can be somewhat
Bob Murrell
M3 Technologies
Photos by Bob Murrell
finicky to polish as they tend to be soft. I have polished a particular (under-lit) onyx bar top for many years now, when the cli- ent wants it to look fresh again. I get a call from them about every 2-3 years, as they do tend to take good care of it. I usually go down to about a 220 grit then proceed to a 400, and then an 800 grit before pol- ishing using Majestic 5X Gold. It works every time, but extra care must be taken as scratching and even heat swirls from the 5X are a constant battle. On some onyx and marble, I prefer the performance of the Majestic DiaBrite 10X or the Majestic XXX polishing powders. It pays to have them on the truck. If you’re not getting the results you expect, and you have tried varying the amount of water to powder ratio, the number of passes or time per square foot, and/or weight of the machine, try the 10X or XXX.
We have so many brands of engineered stones now that I can’t keep up with them anymore. Quartz or engineered stone is basically a material that has similar char- acteristics to granite. They are made of
quartz and resin. We have special polishing kits for the quartz materials called Quartz Renew. It contains special polishing pads which are used with specific compounds that are designed to give excellent results when refinishing these harder materials.
There are also manufactured or engi- neered marbles as well. I have used the
standard polishing procedures for the engineered marbles with good success. You may have to play around and exper- iment with the different polishing pow- ders (like 10X or XXX), but you should be successful.
Please turn to page 18
Polishing a very ornate onyx poses challenges as it contains fairly soft material. Left: Silver Tapestry granite (actually a type of gneiss, I believe) with large inclusions of quartz.
Below: Leathered, resin/color enhanced Negresso needs careful handling.