Glass Polishing for Special Lenses

Polishing a lens is not easy, but not impossible.

Step 1: Polishing Glass: Cerium-oxide

If you have on optical surface, the best solution to polish it is to use a mixture of water andcerium oxide (prepared special for this purpose). Or, you can purchase for example the 3M 60150 material. This is a water based suspention, which you have to use with a clean smooth tool, made for example of wool. OK, this works for plain or uniform surfaces - but what to do, when you have a special shaped lens, which, to make it even more interesting, is made of plastic and not of glass. This is a problem, because if you use a formless piece of wool, you can definitely modify the lenses shape.

So we need a perfect negative of the final lens. The problem is more complicated, when the lens is non-spherical like in my case....

During the polishing you need to work with a concentric and radial movement - so I decided to make the negative form on a small grinding tool, which can be fixed in the power tools used by modelling.

Step 2: Making a PERFECT Negative

I used a 2 component glue named Poxipol, made in Uruguay (!!!). To protect the lens, I covered it with a piece od nylon bag. Pulling it with a certain force covers perfect the lens, and gives a very thin separating layer.

I applied the glue on the surface of the nylon cover, and I positioned the grinding stone perfectly vertical.

After 10 minutes (Poxipol is a wonder...) I just separated the hardened glue - and i have got the negative.

Step 3: Mounting of the Smooth Layer

As a smooth material I used an optical tissue, fixed on it just with some tape. And after 15 minutes of polishing in a plastic box I was like a white pig - but the lens has got back it's original form and shiny surface.

(Just to understand why did I have to do this: unfortunately I whiped this lens whith some methanol during cleaning. It was a fault: the lens has been damaged immediately.)