Bob Murrell 

M3 Technologies

Photos by Bob Murrell

Tools used for the scratch and acid test for granite or marble are the same: a small pocket knife, and muriatic or hydrochloric acid. Always test in an inconspicuous area.

Above and below: Tools used for the scratch and acid test for granite or marble are the same:  a small pocket knife, and muriatic or hydrochloric acid. Always test in an inconspicuous area.
Tools used for the scratch and acid test for granite or marble are the same: a small pocket knife, and muriatic or hydrochloric acid. Always test in an inconspicuous area.
These etch and scratch tests show what you’ll see on a marble sample (top) and on granite (below, no visible scratching).

Above and below: These etch and scratch tests show what you’ll see on a marble sample (top) and on granite (below, no visible scratching).
These etch and scratch tests show what you’ll see on a marble sample (top) and on granite (below, no visible scratching).
I recommend using Red Vinyl tape instead of the standard blue painter’s tape when you need to tape and drape a particularly wet job – the red tape adhesive is less sensitive to moisture.

I recommend using Red Vinyl tape instead of the standard blue painter’s tape when you need to tape and drape a particularly wet job – the red tape adhesive is less sensitive to moisture.
Using a 12,000 grit diamond impregnated pad as a finishing step helps most marble and similar-type floors look their best. Use wet at a slow speed with a swing machine to remove any over-etching and swirls from the polishing step.

Using a 12,000 grit diamond impregnated pad as a finishing step helps most marble and similar-type floors look their best. Use wet at a slow speed with a swing machine to remove any over-etching and swirls from the polishing step.

Happy New Year! Well, winter 2017 is officially here, and all of the bad issues that come along with it. I personally have no use for cold temperatures and shortened daylight hours. It is what it is, though. 

I thought I would pass along some more technical tips this month that have served me well through the years.  Some are from my own experiences, and some are from contractor customers I have known. Some are old, and some are new.

In this article I will try to address several important issues regarding stone identification, polishing, stain removal, and the associated procedures involved.

Most of us can probably identify many of the marbles used as dimensional stone. Marble typically has veins and has less depth in the polish than does granite. Marble is comprised of calcium and other minerals.

This means that we have some known quantities that we can test for. Calcium is acid sensitive and is between a three and four on the Moh’s Hardness scale. 

So knowing these two variables, every contractor should have a small glass dropper bottle (you can find these at your local pharmacy) with a strong acid (like hydrochloric or muriatic) inside for the chemical test, and a small pocketknife for the scratch test (tool steel is about a 6.5 on the Moh’s scale, and should easily scratch most marble and similar stones). Be sure to do the tests in an inconspicuous area.

Once you have determined if the stone contains calcium or not, half the battle is won. Calcium-containing stones are usually easier to both cut and polish. One of the first things a technical support person should ask is whether or not the stone you are dealing with is calcium-based (marble) or not. 

Now that colder temperatures are here for sure, you want to keep all of your water-based products from freezing. Cleaners, impregnators (water-based), polishing compounds (both for marble and granite), and Crystallizer should all be kept from below freezing temperatures. Keep machine solution tanks and lines clear of standing water, along with wet vacuums.    

The type of shoes that your technicians wear is a topic of discussion too, believe it or not.

I was taught early on to wear shoes with little to no deep tread pattern.

In fact, old, leather-soled dress shoes were supposedly the best footwear as they did not pick up polishing powders, compounds, or slurry in general.

I have seen tennis shoe tread patterns etched in the surface of many a marble floor, where the technicians invariably got the soles of their shoes contaminated. Shoes with little to no tread are also easier to clean on a towel or rag. I now use a very low tread rubber-soled shoe that is easy to keep clean and does not tend to grab product or slurry.

Of course, this brings up the idea of establishing a clean zone and a dirty zone.

Keeping the clean zone free from cross contamination is key.

Even little things like running the wet vacuum down and back before moving over about 75 percent with the squeegee will keep the wheels and therefore the slurry removal process cleaner.

It’s essential to have clean mop water to keep from the redistribution of polishing products or slurry. Keep the squeegee blade on your wet vacuum clean by also using copious amounts of water when rinsing. A wet vacuum, by definition, can’t be efficient when too little water is used!

Many use white or natural pads for a final buffing out the door, so to speak. I always say, if it ain’t broke, don’t fix it.

However, I have discovered that using a 12,000 grit diamond impregnated pad really helps most marble and similar type floors to look their best. When run at a slow speed and wet under a swing machine, these 12,000 grit pads seem to remove any over-etching and swirls from the polishing step, and generally just make the floor pop. 

I highly recommend trying this on your next marble floor polishing project. As always, do a test to confirm the results and procedure before general application! 

During the winter months there is less natural light available. With not as much natural light to benefit inspection of the floors, sometimes polishing mistakes are not easily seen until the next morning.

Getting this type of call the next day is a true bummer, and those who have had one know what I am talking about. Therefore, I advise always taking plenty of lights with you. I like the newer L.E.D. lights that can be varied in both power and white level. These can simulate natural light very well.

Most all of us use the Tape & Drape and blue tape for masking off sensitive areas. These normally work very well, but when the blue tape gets excessively wet, it can let go and lose much of it’s adhesive qualities.

Therefore, I suggest trying the red polyethylene film tape. It is much more water-resistant than the blue tape and works very well for this application. It does cost more, but is normally worth the difference. So use the lower priced blue tape where you can (up high), and use the red tape to protect those extra wet and nasty locations.

This is by no means a complete list of all technical tips for polishing of marble and similar stones. If you have some tips that you would like to share, please send these to the editor who will in turn get them to me for future publication.

As always, check with your supplier of products for technical support. Finding answers and offering advice on your technical product questions is part of their job 

The phone call or email is free, the advice is free, so what have you got to lose?  

Bob Murrell has worked in the natural stone industry for over 40 years and is well known for his expertise in natural stone, tile and decorative concrete restoration and maintenance. He helped develop some of the main products and processes which revolutionized the industry, and is currently the Director of Operations for M3 Technologies.