Re: [ATM] Fine Grind already Blanchard ground mirror blank back?

[Guy Brandenburg <gfbrandenburg@yahoo.com>]

You forgot about zirconium oxide. I like it a lot. 

By the radioactive stuff, I think you mean Barnesite. I happen to have some of it left over from the 1960's. I don't like it; it doesn't seem to have any effect at all. I think black rouge, which I got from GotGrit (Moulton) has essentially no effect either except for being INCREDIBLY messy.

I like red rouge for final polishing; it's slower than Cerium oxide or zirconium oxide and leaves the surface much smoother than any of the ceroxes I've tried so far.

I agree that polishing the back is probably a waste of time.

I like to use a lot of different grades in grinding; it gives one a feeling of accomplishment when you can go from M302 to M303 or M303+1/2 or from 500 to 600 grit in less than one hour - even though it might not make much difference overall in the process. 
Guy

Jerry <wa4guu@verizon.net> wrote: Wow!  I think this subsurface damage thing has been taken too far.  It used to be that 5 or 6 grades of grit would get a raw piece of glass ready for polish. Now it takes from 9 to 12 grades to get there and we need to do the back too! To a full polish!!
It used to be the argument was about whether cerium oxide, red rouge, or black rouge makes a better surface. Now it is that plus a zillion different brands of cerium or better yet, if it is radioactive maybe that must be the thing to use.
And finally the "acid dip"!!
It's like the diet book craze. What could be next???
Enough already! There are a fine number of things to do when making optics. We don't really need to be chasing "Boogie Men".

Jerry



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"Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved."
- wrote Charles Darwin.
Guy Brandenburg, Washington, DC
My home page on astronomy, mathematics, education:
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