Basic Guidelines for Three-step Restoration Procedure for Polished Stone Floors (Part 1)
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Read Part 3
Please note that these guidelines refer to "average" situations only. It implies that you cannot establish the precise sequence of different steps beforehand. The exact actions depend upon several factors, including stone and situational factors such as:
- The type of stone
- The make of the diamond pads
- The kind of machines available
- The severity of possible etches
- The depth of the scratch patterns
Please always keep in mind that these guidelines are not rigid like stones because professionalism and experience are the most critical factors in a restoration procedure.
Three-step Procedure: Grinding Marble Floors - I
In this analysis, the definition of marble refers to calcite-based stones only. Such stones are available in the market as marble. Some non-calcite-based stones, like ophicalcite and serpentinite, etc., are also sold as marble, but they cannot form part of our current analysis. These guidelines also apply to Dolomite marbles, provided that the final polishing is hotter than average. Similarly, Travertine is also a part of the definition of marbles but needs a polishing compound that is hotter than usual. Moreover, it may need re-filling after the grinding process and before making any fine honing cuts.
1st Step: Grinding
If you observe severe lippage along the walls and all over the floor, you must begin with the floor edges. You may use a right-angle grinder with a cup wheel or start with a de-lippage tool of a 4" 30 or 46/50 grit. You will have to go down on your knees to use such grinding tools. Alternatively, you may also use a specifically designed edging machine allowing you to work while standing up instead of getting down on your knees. By the way, it will provide better accuracy and will be much faster. You can refer to our article on machines and equipment for further details.
After the initial cut, you may use the 100 grit to get rid of heavy scratch patterns caused by the lower grit. You should use metal-bond abrasive elements that are either vacuum brazed or sintered. You may also use electroplated diamond pads, but their cutting action is typically short-lived than brazed or sintered ones.
Follow the metal bond grinding cuts with at least a couple of Resin-Bond honing passes with up to 200/220 grit. You must do this process before starting to work with the balance part of the floor. This edgework involves an approximate area of fewer than one foot from the walls.
It is crucial to get the baseboards removed, especially in dark marbles, if possible. It is preferred to do so for all types of marbles because when you are grinding to the wall, you cannot overlap the first grit with the following ones. It is essential to get a uniform finishing to the floor edges.
After completing the edge work, you may start with a heavily weighted floor machine of at least 200 pounds. It may sport a 46/50 grit sintered metal-bond de-lippage tool. Please ensure that all floor components are flush with each other.
Important Rule #1: Optimum Distance from The Walls
In the first grinding cut, keep a distance of about 12 inches from the walls. It allows a proper overlapping with the following grits, irrespective of edgework: skipped or performed.
You can remove the 46/50 grit de-lippage tools to do the grinding with the 100 grit. The second cut will remove the heavy scratch patterns caused by the first grinding cut. However, you can also use the second cut to finish the grinding work.
Please note that it is not prudent to eliminate every single lip with the first cut itself. It may cause some "negative" lips, which can be a bit frustrating, resulting in overwork on a specific spot to create "waves." Such Small "negative" lips will escape the grinding work of the first cut. Once you pick up the grinding slurry with a dry and wet vacuum cleaner, those "negative" lips will be visible.
An intelligent operator can take advantage of the grinding action of the 100 grit to achieve two objectives in one shot. You can also consider highlighting the little "negative" lips left after the first grinding cuts with a crayon marking and then increasing the machine weight, if possible. Please don't use a magic marker at all.
Important Rule #2: Working In 50 Square Feet Sections
An old saying is quite valid here.
"the first grinding cut separates the professionals from the amateurs."
Suppose you don't operate the grinding machine correctly in the first grinding cut. In that case, you may irreversibly damage the floor by creating waviness which only becomes evident after the completion of the floor polishing. How can you avoid that as much as humanly possible?
At the first grinding cut itself, you should target an area of at least about 50 square feet and operate all over it at the same time until you finish the grinding. You may cover almost the same area in the next section and take care of the previous area by feathering it abundantly.
If you work in sections smaller than 50 square feet, you may potentially create floor waviness, as mentioned earlier. You may argue that it will take longer to perform the first cut in this manner. But the opposite is true. In contrast, the cutting edges of diamond grits will stay sharp, and diamond pads will not heat up.
Important Rule #3: Floating Floor with Sandless Grout
In the case of severe and widespread lippage (Average 3/32" or more), you may float the affected floor with sandless grout of the same color as the existing grout. It will create flashing slopes all along the marble floor, and the grinding element will skip the sharp edges of lips. Moreover, it will decrease the wear and tear of your de-lippage apparatus and avoid a high possibility of chipping those tiles. Finally, if you work on authentic geological marble, you can prevent irreparable structural damage: the "stunning" effect of stone crystals in high-impact zones.