Basic Guidelines for Three-step Restoration Procedure for Polished Stone Floors (Part 2)
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2nd Step: Honing
Resin-Bond Diamond Pads
You can mainly use a 100/120 grit resin-bond honing diamond pad. But it depends on what scratch patterns the de-lippage tools have left behind. Sometimes 100 Grit may still leave heavy scratch patterns, and you may need a further de-lippage cut with 200 Grit before resin bond honing.
Several factors will influence the outcome of honing. They include the type of machine used and its weight, work patterns of the grinding phase, and of course, the stone type. Hence, we suggest testing a small area before honing the whole floor. For instance, if 100 Grit resin is not suitable, you may go back to 50 Grit followed by 200/220 and finally 800 Grit.
Please note that these honing steps refer to the use of resin-bond diamond pads, which can deliver the kind of clarity we believe is the best. It is what we prefer to call the most cost-effective and fastest way of achieving the best clarity. Still, there are no set standards, and you are free to have additional cuts as per your preferences.
By the way, you may think that we ignored some of the most popular Grits because we did not list 100/120 and 400/600 in several steps. It is not a mistake. We believe that they are not necessary for the type of marble we defined above because they waste our valuable time. Some refer to it as "Grit-Skipping," but technically, it is not skipping.
Skipping something means that you are disregarding a required step or cutting corners. It is not valid in this case. Firstly, those Grits are unnecessary in the sequence we outlined, and secondly, you cannot say that it amounts to cutting corners because it is not commendable. Even in harder stones like granite and serpentinite, you would prefer not to consider this practice. That would be actual skipping! Let us hope we clarified it to your satisfaction, and for the sake of practicality, from now on, we will refer to this practice as "Grit-Skipping."
The Time Factor
We agree that no matter what the brand of honing pad is, you can start polishing after 800 Grit or even 400. However, please note that the polishing phase will consume much more time. Furthermore, it also limits the application range and performance of your polishing powder. Hence it is not worth it. You have to use the correct type of diamond pads according to your machine, which is crucial to accomplish the best final result. Above all, you also have to ensure that you get the results in the shortest possible time.
To sum up, the following equation is perfect for any stone restoration contractor.
Better Result + Less Time = Increased Reputation + More Money
Suppose you are restoring class C-D marbles or a travertine floor. In that case, you need to refill the natural holes of the stone which factories fill during production because the first two grinding cuts open these tiny holes. Some stone restoration contractors prefer to fill them immediately after the second grinding cut by shaving the filler flush along with the rest of the stone before metal-bond cuts.
Others prefer to fill the holes after the first resin-bond honing cut when they have removed all the visible scratch patterns. It does not matter when to do it. The timing depends on the type of filler material. It can be a latex-modified sandless grout mixed with more latex (and not water) to make a robust compound, "Trave-Fill," a polyester glue similar to what factories use, or even a color-matching caulk. In the case of class C-D marbles, the same procedure applies but to a much lesser extent.
Color-Matching Latex-Based Caulk: The Best Choice
My favorite method is color-matching latex-based caulk. Here, you will have to make painstaking efforts to do it right by taking your time. You may use a flexible 4" putty knife to push the filler material deep into the holes. Initially, it may seem to be a time-consuming process, but it turns out to be a time-efficient one because it is less taxing on the resin-bond diamond pads that you use afterward. The best part is that, unlike other materials that take 24 or 48 hours to cure, you can work with this method within a few hours of Curing time. You can shave and flush the stone surface with a 3" razor-blade scraper. After Curing, you can proceed with the subsequent honing cuts of 200/220 or 400.
Why do I prefer this method?
It is too laborious to handle the polyester resin both in the filling and shaving stages. Moreover, it requires a minimum curing time of 48 hours. Similarly, sandless grout or "Trave-Fill" needs a minimum of 24 hours to cure and also demands an additional cut with metal-bond diamond pads because it wears down within 100 square feet. Moreover, the extra cutting may open new holes requiring more filling time and effort.
To conclude, the multiple benefits of spending extra time in the filling phase outweigh the time saved using other filling methods that float the whole floor. Besides, a good quality latex-based caulk is a terrific stain-free filling material.
In the old days, people used to involve different abrasive means like aluminum oxide "stone" in a magnesite matrix and artificial silicon carbide. Similarly, it may be the easiest to shave the filler of travertine, but it is hard to find and difficult to adapt to the attachments of most machines.
Dealing with Crystallized Floors
One final issue with travertine refers to the possibility of a previously crystallized floor. Crystallization mostly removes the factory filler material from travertine, even in a basic two-step restoration procedure. The filler material is sensitive to solid solutions like nitric and phosphoric acids in their formulas. It implies that perhaps those holes harbor dirt and other contaminants, including chemically altered waxes caused by crystallization. In such a scenario, grinding cuts cannot clean the holes correctly.
You may refer to better cleaning methods and equipment in our article on cleaning and sealing. If you do not follow proper cleaning and filling procedures, it will not allow the filler to bond inside the holes.
The Cost Factor
Finally, travertine stones exact a higher toll by wearing out honing diamond pads and requiring the extra filling. When providing an estimate of stone restoration to your clients, you should always factor in this additional cost.
Important Rule 4: Uniform Honing
It is imperative to ensure while honing a floor that you have to file every section uniformly. You can achieve uniformity only by creating a precise working pattern and always sticking to it all the time. I have tested several different types of marble and concluded that you should not hone any given point on a stone surface less than six times with each grit when operating a "Swing Machine" setup or three times when using a "Planetary" arrangement.
Please note the surprising amount of saving in time between both types of setup. An average planetary or mono-rotary floor machine covers a working path ranging from 17 to 21 inches. Based on this information and my experience, I came up with a unique working pattern that effectively obtains a homogenous floor honing.
This pattern starts from one wall to the other and covers a distance of about three square feet in width. Besides, I considered an extra allowance of about six inches over the top and the bottom for proper overlapping, making a coil pattern. Each six-inch swing of the machine contains the width of this coil.
After reaching the other wall, I would go back to the starting wall in a reverse movement using the same pattern and the pace of work. To compensate for the lack of left or right overlapping, I would work straight back and forth a few times in the two ends of the working section. The working section refers to the starting and the ending points near the walls. You may refer to Figure 1 for a better understanding of this concept.
Figure 1 (Rendering of the working pattern for uniform honing as mentioned above)
For the sake of simplicity, we have explained the pattern on a floor with 12" x 12" tiles. We start from the left wall and run the machine straight up and down three or four times by taking half-feet upwards and downward movements. It will ensure no multiple passing as in the middle of it in the two ends of the working section.
The coil pattern begins after that with the same north and south movements of half feet. We work a strip about 4 feet wide, but the work will be 3 feet for rows number 2, 3, and 4. Once we move to the next section of rows 5, 6, and 7, we will use the extra half feet over for proper overlapping. We repeat the same up and down pattern after reaching the end of the section.
In the planetary machines, it marks the end of the honing pass, but you will have to repeat the whole pattern one more time, going back towards where we started in the case of mono-rotary Swing-Machines.