There are so many products on the market now that are based on every type of superabrasive. From diamond to aluminum oxide. They are of every hardness rating, size, purity rating, shape, and chemical functionality. We have nano particles, and micron sized particles. There is a particle zoo out there. Window cleaners use these products for removing scratches, blemishes, organic and mineral deposits, etched glass surfaces, and even cleaning. There is also no limit to the different applications of such products!
The largest problem that we have when using these products on glass is scratches. The reason can be that the product uses superabrasive particles that are as hard as or harder than glass. Or they are too "sharp". Or that they are not "pure" enough. Meaning that even as little as one percent have particles more than 3 microns. Superabrasive cerium oxide powder for example should be between 2.6 and 3 microns particle size at 99.9 percent purity. The white ceriums are the most pure. Although. The application method can make all the difference. If you are using the correct cerium for example with a spin pad on a rotary machine turned at an angle, so you are ripping into the glass with the edge of the pad;...you will leave waves of zillions of micro-scratches that will become visible in the direct sun. Second story windows will show this effect easier than first story. It is also true that when removing stains the mineral substance of the stains can interfere with the results of your superabrasive product. I have tested products and techniques together on windows in the field before. But on a very limited basis. And with the approval of the customer. The test I am describing here is only to test your product and technique.
I chose to use a mirror for this test. Although others have used plate glass such as saphire glass they purchased brand new. And once tested would view the plate in the direct sun at different angles and distances. Without hydrofluoric acid. My test uses a mirror, with hydrofluoric acid of at least one and a half percent, and in the dark with a flashlight. HF is a rather dangerous chemical. Sulfuric acid also will work. Either way wear goggles and rubber gloves if you chose to do the test.. OR call me and I will do the test for you. Or might have already tested your product.
My test involves purchasing a new mirror. Then using the product in question just like you would on your job. You then should wet only half the area you worked on with your superabrasive product. You could tape off half the area. Next clean the mirror with just soapy water and a squeegee. Take it into a totally dark room and look down the beam of a flashlight at the mirror. If there are any scratches showing as errant scratches or waves of micro-scratches, you will see them rather easily. They might even be visible on the side of you work area that did not make contact with the acid. But will definitely be very strongly visible on the side that did make contact with the acid.
This is a very difiinitive test and will serve you well.
There are may different products available out there. As I continue to write about the many hundreds of tests I have and am developing, I hope you can use them to your advantage. I will also be making these different products available to you if you are a member of IGSA. But only if you are a member. So I advise you to communicate with me by email so I can put you on my email list. One that I should have started so very many years ago!
Henry Grover Jr.
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