Quartz Countertop - Myths and More

Quartz countertop is almost indestructable, many manufacturers tend to sell us this myth. Truth is that quartz countertops do react to some chemical agents, although they do withstand many types of chemical and physical stress.
Quartz countertop fabricators will have on hand a leaflet from the quartz slab manufacturer, most of them have a page dedicated to what may or may not damage your countertop. Their labs and day to day experience have helped them elaborate a list.

What they may say about scratch resistance and abrasion,gloss, fire and heat ...
Without a doubt quartz surfaces are very hard. If you have a countertops fabrication unit, you'll notice that it grinds your diamond tools pretty quick.
Quartz surfaces contrary to what manufacturers say does:

•  Scratch - I had a claim, on a dark blue engineered quartz, they had a glass bottle with a rough bottom, and with some friction it did leave marks on the quartz countertop
• Warp - I've see long slabs warp, due to warehousing or heat. In truth I've seen a genius in stone vanities do a rounded support for the quartz vanity with localised heat.
• Crack - they say it doesn't crack, I had once a claim from a countertop fabricator, while fabricating the countertop some would break when doing the sink cut out ... I figure it had excess tension on that point, and he didn't respect the cut out procedure (namely drilling wholes in the four corners of the cut out)
• Stain resistant - there is the good part, I had once a quartz manufacturer who for some reason started identifying slab defects with a Eding 3000 type permanent marker .... guess what, it stained, it actually was absorbed by the slab. Sodium hydroxide can also stain you countertop ... At the laboratories they test a limited range of products, and we all know that the detergent companies are constantly creating new more powerful and effective products, so be careful.
• Resist to Heat  - some manufacturers say their product "can tolerate brief exposures to moderately hot temperatures without warping, staining, discoloring or cracking." I say, heat in direct contact with quartz may damage it permanently, so be very careful, don't ever risk putting a hot pot or pan on your quartz countertop.
• Resist Fire - it's made with 5-10% resin, but it is fairly resistant to fire. People sometimes approach me with this myth. I will share a true story .... once I was in a meeting with a potential client, he had never worked with engineered stone, but said that he had herd rumours that it was highly inflammable and that it would light up with a simple lighter, so I left the meeting room, picked up a lighter and a piece of engineered stone, and asked him to demonstrate that theory ..... nothing happen as it was obvious, the resin is in a solid state and its percentage is relatively low. Although it does burn at a certain high temperature.
• Have an even gloss - gloss is very difficult to attain on dark materials, you may have different gloss levels on the same slab, the question is if it is noticeable. Just to understand polishing dark quartz has been a difficult job for all slab manufacturers, as it is for some types of granite. Most countertop fabricators may apply some chemical agents to even off the gloss, if after a while you notice shade differences on your quartz countertop, it might not be your fault.

How to polish cultured marble?

In today's post I'll be focusing on polishing cultured marble. So how do we polish cultured marble? Or better, what are the best polishing techniques and solutions for cultured marble. If you work frequently with cultured marble, you have by now dominated most of the particular aspects of polishing cultured marble. However if you don't work that frequently with cultured marble, I hope this post may help you accomplish a nice beautiful polish.

General things about polishing marble.
Before I get into some technical details, I just want to discuss some basic things about polishing marble in general. I figure that not all my readers may be familiar with the shop floor, machinery and tools used in polishing marble.
Polishing marble, using a slab polisher or even a small manual system, you'll use in the majority of the cases a Frankfurt system abrasive. What does this mean? The Frankfurt system is specially designed abrasive, it looks rather like a horse shoe and fits into to the slot in the polishing heads plate.
On our right you'll see a couple of Frankfurt abrasives, all Frankfurt are similar in shape, although some have a plastic base to fit into the machine. Normally the plastic base is for abrasives that break easily, when fitting them on the polisher, it needs a little bit of hardness to be able to secure itself onto the polishing plates.
The Frankfurt abrasive sequence is made up with different coloured abrasives, or even different type (configuration/moulding). Many manufacturers relate colour to grain size, so you'll be fitting into your polisher several grains of abrasives, from the lowest to the highest ... and at the end, you'll need gloss/shine abrasives. Polishing marble requires a chemical polish, so the yellow abrasives are normally the gloss/shine abrasives, these are very soft and the least resistant abrasives, although they have an important role in polishing marble.
I've mentioned slab polishing machines, well just to get you familiarized with them, there are several types, namely differing in width and in polishing heads. The width varies significantly, you will find machines that work 60 cm materials, 80, 100 and then you'll find 180 and 240 ... the width is very important as it limits the width of the material you are able to polish. I have a photo of a polisher for slabs:

 A marble slab polisher can weigh up to 30-40 tons, the more heads available will guarantee speed and quality to your polish. A machine like the one in the picture may use more than 90 frankfurt abrasives simultaneousely, which becomes a serious production problem to manage, as each type of abrasive has a different usage time, so constant set-up times are needed during the day. (I haven't mentioned the diamond based abrasives which last for a few thousand sqm and are better for production flow)

I also mentioned the manually polishing equipment, I've included a picture of a blue machine on the right, so basically it uses a dish on the end, which normally has 4 Frankfurt abrasives attached. To reduce set ups and other productivity issues, normally you'll have several dishes one for each abrasive grain in the approved sequence.



Why is polishing cultured marble such a big deal?
In truth, each type of texture and colour in cultured marble has their particular polishing sequence. So, unlike most marbles, you'll have several grain sequences and pressure defined for your cultured marble. One thing that is at the base of the polishing problem is the polyester resin from which the cultured stone is made with. The resin in the cultured stone is the main reason for many polishing problems regarding cultured stone. Some of the abrasives themselves also use polyester resin for their bonding which does not facilitate polishing cultured marble.
The cultured marble that uses fine grain in it's texture is more sensitive to polishing, a little too much pressure, or too little cleanliness of the water .... and you'll have shade problems and micro scratches.
Cultured marble should havea measured gloss between 70 and 85 points, when we relate to engineered quartz the numbers go lower and in most colours you'll have gloss index of 50-60 points.
Being cultured marble sensitive, shade problems sometimes can be hidden due to lighting, direct lighting on the polished cultured marble will not help you detect the polishing defects.
In my opinion, cultured stone shade varies significantly due to polishing, if you polish one slab using one abrasive sequence and particular machine parameters, to reproduce the same shade in future productions, you should maintain all these variables stable. 
Another typical problem, related to thickness of the slabs, especially regarding tiles, when the 10 mm or 12 mm slabs are polished, the machinery has to be top maintained to get a good job done. It has to be very well levelled and stable. Imagine the weight of the polishing heads, they are in constant movement, and the slab underneath being thin may have tendencies to react. (to check if a polisher is stable I usually use a coin a put it on it's side, when the machine is working it should maintain still, even with the bridge movement, that's how stable you need your polisher)
Now I'm on a roll here, another thing that may cause dreadful problems in non calibrated slabs, or warped slabs, you can imagine a warped slab being polished, it's almost impossible to get a top and even gloss on the whole surface, and frequently the slab will break.

Polishing cultured marble requires a lot of testing of different types of abrasives, and on the production floor abrasive sequences testing. Just a hint for my readers, you may need for some delicate textures soft abrasives, the Italian manufacturers classify them as T type or even TT. T for tender, and TT tender tender ... very soft. In most cases, the abrasive sequence is not standard, which means ... it gets complicated after the grain 400. And the gloss abrasives at the end, are the ones responsible for the shiny look of the cultured marble, these are very difficult to find (good quality at a good price).
Most European manufacturers of cultured stone will sell you polished slabs, which you can avoid most of the problems they have to deal with on a day to day basis, but you can buy blocks from some manufacturers and then you'll need to really look seriously at your machinery and production.