So with various hairlines in my U1's ar coating I decided to try removing it using the resource of various threads here on WUS. I started with .5 micron diamond paste and worked at it with a cotton rag with little results after 20-30 minutes. I noticed a few more scratches appearing and assumed this to be the middle phase I have read about. Everyone says it gets worse looking as you cut through. I then switched to a dremel polishing wheel installed on my drill press with the paste. Another 20 minutes and it looked roughly the same. Frustrated I switched to Mothers auto metal polish and went to town with the drill press. After 20 more minutes I cleaned it and I have hundreds of hairline swirly scratches on the crystal. Is it possible that the paste was too abrasive and I trashed the crystal or am I just not through the coating yet? I fear the worst.
Sinn U1 AR coating removal. Did I go to far?
dnslater
21 - 26 of 26 Posts
The particles in the polishing compound still need to be harder that the surface that you want to reduce ( polish).
Let me make an extreme example: You will never be able to polish a Diamond with Talcum.
High RPM can heat up the surface, which will make some surfaces softer.
I work all day with an instrument that does 350 000 RPM, but I can not use a soft iron bur to go through amalgam. For that I select a bur with Diamond coating, but could use a Carborundum tipped burr too.
Let me make an extreme example: You will never be able to polish a Diamond with Talcum.
High RPM can heat up the surface, which will make some surfaces softer.
I work all day with an instrument that does 350 000 RPM, but I can not use a soft iron bur to go through amalgam. For that I select a bur with Diamond coating, but could use a Carborundum tipped burr too.
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Ewwwww. You play in people's mouths! You're not touching any of my watches!
Yeah, I know the high RPM builds heat. Was mostly a joke. But I have done this around 8K - 10K and some regular polishing compound. It didn't happen fast, but that is the way I want it in any case.
Whatever. It worked, I would never do it that way, but the customer is happy. And there it is.
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Unfortunately it all worked out if you read my follow ups on the first page. Besides Raza you need that $$ for your "one" purchase later in the year.
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No, I saw that. I just think you reached a premature conclusion.
You see: I do not understand the claims some manufacturers have about " hardened AR coat" as the agent is simply sprayd on the crystal.Ewwwww. You play in people's mouths! You're not touching any of my watches!
Yeah, I know the high RPM builds heat. Was mostly a joke. But I have done this around 8K - 10K and some regular polishing compound. It didn't happen fast, but that is the way I want it in any case.
Whatever. It worked, I would never do it that way, but the customer is happy. And there it is.
IF it is as hard as they say, it would be almost impossible to polish away. The OP's Sinn is supposed to be hardened. But he scratched it, and then removed it.
I do not see any way to test the hardness of the AR, not unless we destroy it.
For the same reason, the manufacturer has to trust the supplier.
I wish I could trust Sinn. But I certainly have a question mark in my mind!
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