Polishing a BK7 Prism to 4020 Scratch Rating

[Desh627]

I have a bk7 prism (borosilicate...) and I'd like to polish it to a 4020 scratch surface rating. How would I go about doing this?

 

[Andy Resnick]

I think you mean 40-20 scratch and dig.

http://optical-technologies.info/?tag=scratch-dig

I suspect any wet sandpaper of fine enough grit would work (http://www.sisweb.com/micromesh/conversion.htm), but you may want to ask these guys:

http://www.cidraprecisionservices.com/pm/materials/BK7.html