About 90% of it was lap on top.
I was getting a lot of screeching last week with the new CO from Willmann Bell, and some people suggested the following changes:
1) Put 1 part CO and 5 parts water (presumably by volume) in a bottle and use that.
I get about a 1-minute wet, and then SCREECHHH
2) I doubled the amount of CO
I get about a 2-minute wet, and then SCREECHHH
3) Add a drop of dish washing liquid. I used _Dawn clear_
I can now get a 5 to 7 minute wet before screeching.
My room is at about 70 degrees F and I have turned off the forced air heating in the room, so I have no drafts or air movement.
Well, anyhow, the edge pits are fewer, but I'm tired of polishing, so I did some mirror on top long (Like 3/4 D) strokes to parabolize the mirror, and then tested it with my Couder mask.
I took four zone readings, and went upstairs to fight it out with the Texereau book.
About 90 minutes later, I had computed the billion values in his spreadsheet like form, and the result is...
The maximum deviation from a parabola is 1/16 wave.
Now, I really don't believe that I just lucked onto getting such a good parabola the first time without even trying, so I expect that I dropped an order of magnitude here and there, and I have a One-wave mirror or so. (An 8 Inch f/7 mirror that is spherical is a One-wave mirror)
I'll take several reading, and rotate the mirror 90 degrees, and take several more like Texereau suggests, and then compute all over again and then I'll get back to you all.
-Alan Kilian