Mixing
-
Buy some oxalate crystals to prepare an oxalic acid solution. Online Home & Garden distributors usually sell them in bulk but if you'd prefer a slightly less-expensive option, go to your local independent (or big box) hardware store and ask for wood bleaching agents. Read the back of each product. Some will contain trisodium phosphate or sodium percarbonate; ignore these. What you want is one that lists "oxalic acid" as the main active ingredient.
-
Taking a 12 oz. cup, transfer about 2 cupfuls of crystals into an empty 2- to 5- gallon bucket.
-
Slowly add five (5) cupfuls of water to the crystals and mix with a garden trowel. Do not use a pointed grout or masonry trowel; you'll be using the same tool to apply the oxalic acid to the stone and you don't want to risk scratching the surface.
-
The ideal consistency for this oxalate polish is a wet-paste, similar to that of a milkshake. Depending on the crystals you obtained, you may need to add more water. Either way, make note of the crystal-water ratio that works best for you -- you may have to mix new batches multiple times, depending on the size of the area.
Polishing
-
After achieving a milkshake-like consistency, scoop up a trowel's worth of oxalic acid and spread across the stone, creating a thin layer (~1mm) over the area to be polished.
-
Allow it to sit for 5 minutes
-
Polish the surface with a camel hair cloth until glossy. You can use a machine but use a slow speed and check the glossiness of the floor frequently to avoid etching.
-
Once you've completed the entire area, rinse all the surfaces thoroughly with water.
-
Mop up excess water.
-
Let the surface air-dry for at least 12 hours, making sure that no one walks on it.
-
Apply the appropriate stone sealer (NOTE: granite, marble, limestone and other decorative stones generally use different sealers. Consult your local hardware store or marble fabricator for details).