Re: ATM [long] Getting the smoothest mirror (no dog biscuit)

["Michael J. Coslo" <mjc5@psu.edu>]

>figure, smooth, dog biscuit, ripple, zones

>How do you get a _really_ smooth figure?

>"Tool size"
>    Some say bigger, some smaller, mine is 100% of the mirror with a nice
>beveled edge.

I think that the disparity is because of the individual's type of stroke. .

>"Use slow strokes"
>    How slow?  I'm going pretty slow.

Slow and smooth might be a better choice. If you are doing one second for
the "zig" and one second for the "zag" part, you should do pretty well.

>"Use light pressure"
>    How light?  Just my hands, or even less?

        The weight of the mirror, and your hands should be good when figuring.

>"Refine the CeO to make 'the good stuff:'"
>    Mix CeO and water, settle for 30 seconds, pour off the good stuff or
>    Use a cloth square to make a "tea bag" of CeO and kneed
>    it in water until the good stuff leaks out (al la ATM books).

        This is one of those things that makes me think some of us are a
tad bit too fussy. This would indicate that what is left behind is not the
good stuff, and was more or less bad for the mirror. The tea bag is a
little funny too, the CeO is a lot smaller than the weave openings.

The best bet is to be sure you have good CeO to begin with.

>"Use rouge in place of CeO"

        15 years ago this was true. I'm not so sure anymore. Like someone
here said, "This is not your father's Cerium Oxide".

>"Press press and press again."

Having good contact is important.

>    Keep good contact - warm with a hair dryer and press, press, press.

        I prefer a warm water dunk, it is less localized

>    Do short (minute or two sessions) then press press press.

        Gotta disagree with this one. In general, longer sessions are
better. And You should already have good contact when doing this, so
stopping the polishing process is a really odd thing to do.

        Also, it is best to wait until all the heat is out of the lap
before starting the figuring session.

>"Keep it wet"
>   Don't let it dry out and get all screechy.

        Wrong.

>"Channel my way"
>    Wide or narrow, seems some people say narrow is best?

        Either works, the important thing is to have a channel. I like
wide, because I don't have to channel as often.


>    Lots of 1/3 COC but there is some talk of W and zig zag, what's the deal
>here?

        The deal is that there are several ways to make a good mirror! 8^)
As you progress, you learn that different strokes produce and correct for
different mirror conditions.

>"Watch the drag"
>    Its supposed to be even and steady.

        Don't forget high also.

> What about straight
>    strokes where you stop at the end of each stroke?  Should you keep it
>moving?

        Are you referring to a little circular motion at the end of the
strokes? I wouldn't do that myself, but might not hurt. In any event, just
stopping and returning works fine.

        You sound like you are coming along just fine from your description
of your mirror. The learning curve on making mirrors is steep, I'd say
about f1.2 or so, just continue as you are, and your mirror will work out
well.

        - Mike -