We get asked this daily. There is really no definitive answer as in most cases there is a crossover area where both are as effective as the other.
The only way to really compare the two processes is to actually talk through the products individually and explain what they are designed for. That way you can make the most suitable choice of product for your particular set up.
Wet Diamond Pads
These tend to be Velcro backed pads with diamond or diamond dust suspended in resin (sometimes resin and copper). Using water with these pads keeps the resin cool and stops the pads overheating and burning out too quickly. The water also helps remove the waste material that is being “cut” by the polishing process in the form of a slurry.
The lower the number the more coarse the pad.
Wet polishing consistently produces the best finish when looking for that mirror shine finish. The pads are less expensive than the dry variants but the machinery to use them is generally more expensive. Oh and it’s very messy. You’ll need wellies and a full length rubber apron if you want to stand any chance of keeping dry.
Wet diamond pads will polish pretty much anything from porcelain, marble, terrazzo, quartz, limestone, travertine right up to the hardest granite.
In every tile, stone and quartz factory in the world there will be line polishing machines using diamond pads cooled by water for finishing the surface of the products.
Dry Diamond pads
These tend to be Velcro backed pads with diamond dust suspended in resins, the difference with the wet pads is the resin is more dense (harder) and able to withstand higher temperatures. Fundamentally they work in the same way as wet pads, by wearing away the resin to expose the diamond which polishes the surface. The lower the number the more coarse the pad.
The obvious advantage is you don’t have to dress like a fishmonger to use dry pads. Also they can be used where wet pads simply wouldn’t be practical, i.e. on a finished job or for smaller jobs where a full wet set up is just going to take too long. But they do create dust, so if you’re polishing in volume dust extraction becomes a consideration as does filtering the air you breathe by using masks etc.
Filtering is particularly important with some man made products such as engineered stone or quartz as there is some suggestion the dust produced while polishing these products could be a carcinogen. The jury is currently out on this but better to play safe.
The technology now is such that the performance of dry pads is pretty close to wet pads for surface finish, there’s not much to choose between them.
The dry pads are more expensive to buy than wet pads, the resin is harder to cope with higher temperatures and as such dry pads tend to be more suited to harder materials such as granite and particularly dense concrete.
You can polish “softer” sedimentary or metamorphic stone such as limestone, travertine and marble with dry pads, but they often need to be “dressed” before first use, that means running them in on something very dense like black granite to first expose some diamond.
Silicon Carbide Pads
These pads are made up of a fine grit of Silicone Carbide (SiC) which is also known as carborundum, glued to the face of paper discs. The size of the grit determines the coarseness of each pad, just like sandpaper or wet and dry paper.
The pads come paper backed or velour backed. The paper backed are cheaper and you’ll need a plain backer and some contact adhesive onto which to stick them. Most masons use a variety of carpet/vinyl contact adhesive that can be picked up in most flooring stores or on line.
The velour backed pads are attached to a Velcro backer, so you don’t have the nuisance of sticking and unsticking the pad each time you need a new one, which can be quite often. Obviously you pay for the convenience, so the velour backed pads cost more.
These pads have a very short lifespan but are inexpensive buy costing £0.30 to £0.45 per pad depending on the volumes bought. They are throwaway items like sandpaper.
The velour backed pads are used exclusively dry. The plain backed pads are used dry up to P-320 grit and above that can be used wet, from P-400 through P-1200.
SiC pads will polish:- Marbles, travertine, limestone, porcelain, quartz, fibreglass, plastic materials and glass. They are extremely versatile and as such you will find boxes of these pads in every stonemasons yard or factory.
The only reason to step up to using diamond pads is for economy purposes due to the volume of SiC pads you’re using or for convenience. One set of diamond pads will outlast a few boxes of SiC pads.
The Machines
There is a vast array of machines available for use with polishing pads of all types. So for the purpose of this comparison I’ll pick the two we sell in reasonable volume.
FLEX LW1503 wet polisher. This is a dedicated polishing machine. It has a 800w motor soft start and an attachment to accept any garden hose for a water feed that sends water down the centre spindle through the hole in the centre of wet diamond pads. Fixed speed of 3700 rpm – 110v only.
If you’re looking for a good quality dedicated wet polisher, this is it.
If you’re looking for wet machine with variable speed the you’ll want the LE 12-3 100 variable available in either 230v (with PRCD) or 110v. It has a powerful 1150w motor and a speed range of 1200-3700 rpm.
You could also use our profiling tools with this machine with or without centre water feed.
FLEX L1506VR polisher/grinder. This is quite a versatile machine which is why they are popular. It has a powerful 1400w motor, soft start and is speed variable from 2200-6800rpm. Available in 110v or 230v.
This is an ideal multi purpose machine if you want to do more than just polish. Grinding and cutting at 6800rpm gives you more control. This is an ideal if you’re looking for a machine that will do controlled cutting and grinding which will also do a little polishing.
If you’re wanting a dedicated dry polishing machine we’d recommend the FLEX L1503VR this is a dedicated polisher with a speed range of 1200-3700rpm.
We do see this machine used with wet pads occasionally with a hose set slowly trickling across the work piece and wet pads attached to the machine. If you are going to use it in this manner we’d strongly suggest getting the 110v version. Obviously it’s meant to be used dry and isn’t designed for getting covered in water.
With any variable speed machine, no matter what manufacturer you chose it’s important to buy the appropriate piece of equipment for your intended long term use.
Variable speed machines don’t cope well with being used for extended periods of time at the low end of their speed range, they tend to overheat. By extended we mean 30 minutes
