Slippery Rock Gazette

Tom  McNall

Floor Restoration Consultant

Well, it’s February 2013 and although the Mayans didn’t see it coming, we have another Valentine’s Day upon us. And aside from chocolate, what do all the ladies out there really want?

As Marilyn Monroe so elegantly put it, “Diamonds are a girl’s best friend.” And in the stone restoration business, they are also (if used correctly) a technician’s best friend.

Most of the diamonds used in the stone industry are not mined anymore. Since the latter half of the 20th century, manufactured or “synthetic” diamonds have entered the market and made it more affordable to produce the cutting, grinding and polishing tools that we in this industry use. It has also made the use of stone more affordable to the world which is why you are in the job that you now have and affords me to write about it (otherwise, why would you be reading this?)

Now, unlike the majority of other synthetic materials, man-made diamonds are actually better for our stone use because they are actually harder than real diamonds. That means that your tooling can cut quicker and wear longer.  You would think that fact would crush the world’s gem diamond market and make them more affordable, and perhaps put the monopolies that control the world’s natural diamonds out of business. 

Well, as of yet, synthetic diamonds may be harder than the real thing, but they are sure not prettier, which protects the Crystal Kings.  However, De Beers is working on it.  Considering that they dominate the diamond industry world-wide anyway, it would be like asking OPEC to develop synthetic oil.

Now, in the restoration end of the business, we have what are commonly referred to as resin bond diamonds and metal bond diamonds. Metal bond diamonds are essentially diamonds that are either entombed inside of a metal alloy or electroplated to the outside of a metal tool during the manufacturing process.  

Metal bond diamonds are generally used for de-lipping floors, removing coatings and shaping stone as in countertop edges and such.  Because metal holds the diamonds tighter and does not wear as fast when used against stones of variable hardness, these diamonds tend to be more abrasive than their equally-sized grit resin bonded counterparts.

As you’ve probably figured out by now, resin bonded diamonds are essentially diamonds that have been molded into various plastics. Resin diamonds are great for finishing because the softness of the plastic (compared to metal) allows the finer and finer grits to be exposed so that they can do their job and remove the scratches, while still holding the diamonds in a stable matrix.  

If you were to use an 800 grit metal bond diamond on a soft limestone floor, you could risk the metal making bigger scratches than the actual 800 grit diamonds inside the metal would, and thus, defeating your original purpose. The plastic ones, however, will do no more than leave a crayon-like scuff mark that is easily removed with the next step or final polishing.

So, what do all the numbers on these diamonds mean? Well, as long as manufactures stick to the traditional numbering system, it essentially tells you the size of the grain of the diamonds that are in each pad or tool. 

Here is how it works: A 50 grit diamond means that the screen used to sift out these diamonds from others will have 50 holes evenly per square inch; 100 grit will have 100 holes per square inch and so on and so on….

So, why do we need so many grits? Because essentially, what we are doing each time we go up a grit level is removing the scratches made from the previous one.  

“OK, wise guy,” a neophyte asks, “then why don’t we just skip right up to the highest grit right away and save time and money?”

Well, the answer, my friend, is simple, because you will save neither and only drive yourself insane in the process. When working with a hard surface like stone, to first remove a scratch, you have to remove the stone around the scratch. To do so with a fine-gritted diamond would take you forever because it does not dig very deep (picture the holes in the sifting screen). 

You need a diamond tool with a little more scratch to it to remove all the stone needed to make the surface “appear” smooth. I say appear, because essentially, you’ve just scratched the life out of the surface around the original scratch, but with one caveat – these scratches are controlled ones.  There is a pattern to them and they are finer than the original.  

So now, as a stone restoration technician, you control the scratches. You can be “The Scratch Master.” Each time you go up a grit level, you are making finer and finer scratch patterns until they are so fine, that they are not visible to the naked eye. And because stone is so hard, skipping grits will not save you any time because the finer grits cannot dig deep enough to remove the surface around the scratches left by the coarser ones. To quote my favorite fake broadcaster Ron Burgundy, “It’s not me, it’s science.” 

So, now you know a little more about diamonds. The diamonds that can make you money, anyway. Be careful this month of those other diamonds out there that can end up taking your house, your car, your dog… half your pay check. But that, my friends, is a whole other story. Until next time, keep your stick on the ice.

Tom McNall is founder and owner of Great Northern Stone, an Ontario-based stone cleaning and restoration company servicing Ontario and Chicago, Illinois. Tom also offers corporate and private consultations as well as speaking at conventions. He can be reached at tom@greatnorthernstone.com .