Abrasive Types
The grit used or the material used to make an abrasive can vary. For those of you familiar with sandpaper, you will notice there are several different types, i.e. aluminium oxide, silicon carbide etc. These are the abrasives that make up the sandpaper. They are nothing more than powders of varying grit size that are attached to a paper backing. In the stone industry we use similar abrasives. The two primary types are silicon carbide and diamond powders. These powders can be attached to backing in various ways just as the sandpaper is or they can be added to a mixture and formed into a solid block. Most stone refinishers today use diamond abrasives but be aware there are other types. The following are the abrasive
shapes and types available.
Abrasive types:
The following are the abrasives that are used to construct the discs, bricks etc. that abrasive tools are made of.
Silicon Carbide
Diamond Powders
Abrasive Shapes:
The following are the many abrasive shapes that are available for grinding, honing and polishing. Today, the diamond abrasives are the most popular for stone refinishing in the field.
Bricks– Brick abrasives are composed of silicon carbide (the abrasive) and magnisite or polyester (the bonding agent). The abrasive and the bonding agent are mixed together and poured into a mould. The mould is cooled and the result is a brick form. Bricks can take many shapes but the most common bricks are known as “Frankfurt” and IICassini”.
Grinding is recommended when the lippage exceeds 1/8 inch or if one desires to have a completely flat floor. There are some very good reasons for grinding a stone floor flat. A flat floor is easier to maintain; since there will be no lips where dirt can accumulate. The grinding process, if performed correctly, will also eliminate depressed grout joints-the grout will be even with the tile’s surface so that dirt and grime can’t accumulate. A completely flat floor eliminates all unevenness, giving the floor the illusion of being monolithic (one piece). Note: a stone floor does not necessarily have to be ground to remove scratching. A skilled craftsman can repair it without grinding. Just as there are several good reasons for grinding, there
are also some disadvantages. Grinding is very time consuming and expensive; with some hard stones, like granite, it can take an entire day to grind 50 square feet. The grinding process is also very messy. Copious amounts of water are needed to grind a stone floor and produce a heavy slurry of stone and water. If adjacent areas such carpet, wallpaper, baseboards, etc., are not protected properly, water damage may occur. Before deciding on grinding, all the above considerations must be carefully weighed.
HONING
Honing is the process of smoothing the stone with the use of abrasives. Although not as aggressive as grinding, it does require the use of water, and can also be quite messy.
Honing is performed to remove scratches, and will not remove lippage (uneven tiles). It can, however, round the edges of the stone, giving a smoother finish to the edge. The honing process is usually achieved with the use of diamond abrasives, although some contractors prefer silicon-carbide bricks or screens. Which abrasive is used is not as important as the skill level of the craftsman. Honing can leave a stone floor with very little shine, although some stones will acquire a satin-like lustre at very high hones.
Generally, grinding is what takes place using any grit of 60 or below; honing begins at 120 and proceeds upwards. A skilled craftsman will generally stop at a 400 or 600 on marble before polishing. With granite, it is usually necessary to proceed through to the highest grit. Some craftsmen may choose to polish with diamond abrasives to the highest grit, producing a very high polish, while others may choose to switch from a diamond to a powdered abrasive (see next section). Whichever method is chosen, the final result is what counts.
POLISHING
Polishing is defined as placing a high reflective finish on the surface of the stone. Polishing is usually accomplished with super fine abrasive powders but, can also be achieved with super-fine diamond abrasive discs.
MG-01A & MG-01 Refinishing Procedure For Marble Granite Floor Combinations
Many architects and designers are combining marble and granite floor tiles. Small square insets are placed in marble floors and elaborate designs combining polished marble granite alternating in strips are not uncommon. While the overall appearance is pleasing restoration can prove difficult.
There are two procedures for restoring marble granite combinations depending on the amount of granite/marble used.
MG-01A is used for floors which contain mostly marble or where no apparent work is need on the granite. This is quite often the case since granite is much harder than marble and will not wear at the same rate as marble. This would apply to marble floors with granite insets and
granite borders, etc. MG-01B is to be used where the floor is more granite than marble and in installations where the granite needs work. This is quite often the case with checkerboard patterns, lift
cabs, etc.
DP-Ol Dry Polishing Procedure For Marble and Granite
Certain marble and granite types respond poorly to wet polishing methods. If this is the case it may be necessary to apply the dry polishing method as outlines below:
The following procedure uses a standard 17″-20″ 175 to 300 rpm floor buffing machine.
Step 1. Remove all furniture from the floor surface. Be careful not to slide heavy pieces across the floor since this can cause irreversible damage.
Step 2. Protect all wall surfaces and baseboards by covering with plastic or paper sheeting. Tape plastic/paper to wall surface using only low-contact masking tape. Protect walls to a height of at least 24 inches measured from the floor up. If dealing with a sensitive wall surface such as silk wallpaper or decorative painting, test the tape to make sure it does not damage these surfaces. Adjacent carpeting should be pulled back or covered. Wood flooring and other water sensitive material should
also be covered.
Step 3. Dust mop entire floor to remove loose debris. Scrap any large chunks of grout or thin set and remove any tape, gum etc.
Step 4. If the floor has a heavy application of waxes or other coatings, these will need to be removed before refinishing. Use a stripper designed to remove the coating and following manufacturer’s directions for procedures.
Step 5. Place a polishing pad under the floor machine A white or tan pad is recommended. Refer to instructions of polishing powder for pad recommendations.
Place approximately one teaspoon of marble polishingpowder under the polishing pad. Add a little water and begin working the machine in a slow back and forth motion. Add only enough water so that the circular pattern left by the slurry is visible. Continue to work the slurry until the floor becomes dry. DO NOT add any more water. The machine will be difficult to handle at this time. Continue to move the machine over the dry floor until a shine is obtained. This may take several minutes.
Work in small four by four foot sections.
Step 6. Continue to work dry. When the desired shine is obtained, immediately apply clean water to the area. Pick up the water with the wet vac. Before moving to the next four by four foot section, apply a thin layer of clean water to the section you just
completed. Keep this section wet and you will not etch the newly completed section with the splash from the floor machine. Continue polishing in this manner until the entire floor is complete.
Step 7. Once the floor is entirely polished, rinse the entire floor again. Place a clean white pad on your floor machine and buff any remaining film or residue. Wait at least 24 hours before applying any penetrating sealers or any applications of crystallisation/vitrification.
Continue to work the machine in a slow and steady fashion. Make sure that you are covering the entire area and that you do not have any splash over. If necessary run the machine over a larger area to cover any splash. Run the machine until all the fluid is dry and any streaks have disappeared. If the area is polished moved to the next section. If not continue by spraying more fluid on the floor and repeat.
Step 8. When the entire floor has been crystallized, inspect it thoroughly for spray marks, streaks, etc. If these are found, re-crystallise the area.
Step 9. Once the entire floor has been crystallized, cleanup all steel wool dust by sweeping, dust mopping or vacuuming. A magnetic broom may also be used to pick up stray steel wool fibres.
Caution: It is important to remove all steel wool, since any remaining fibres can rust and cause staining on the stone.
NOTE: Many manufacturers of crystallisation products have two-three steps processes. Be sure to follow
manufacturer’s directions carefully.
M-01S Marble Polishing Procedure For Green and Other Hard Marble
The restoration and polishing of green and other hard marbles is similar to soft marbles with the following exceptions. Harder marbles generally need to be honed to at least an 1800 grit before polishing. Some hard marble may also require the dry polishing technique…The following procedure uses a standard 17″-20″,175 to 300 rpm floor buffing machine.
Step 1. Remove all furniture from the floor surface. Becareful not to slide heavy pieces across the floor since this can cause irreversible damage.
Step 2. Protect all wall surfaces and baseboards by covering with plastic or paper sheeting. Tape plastic/paper to wall surface using only low-contact masking tape. Protect walls to a height of at least 24 inches measured from the floor up. If dealing with a sensitive wall surface such as silk wallpaper or decorative painting, test the tape to make sure it does not damage these surfaces. Adjacent carpeting should be pulled back or covered. Wood flooring and other water sensitive material should
also be covered.
Step 3. Dust mop entire floor to remove loose debris. Scrap any large chunks of grout or thin set and remove any tape, gum etc.
Step 4. If the floor has a heavy application of waxes or other coatings, these will need to be removed before refinishing. Use a stripper designed to remove the coating and following manufacturer’s directions for procedures.
Step 5. Place 3 to 6 60 grit diamond discs on the pad driver of your floor machine.