[ATM] Dry Polishing .. Long

[vorblesnak@peak.org]

For what it is worth, I have polished with paper and dry cerium.  The 
only thing I could add is use no pressure, the weight of the glass is 
enough.  I have used it to bring out a quick shine to look at the 
curve.  I don't know how a finished mirror would look.  Here are a 
couple of references from the past.

A bit newer than Guy's reference.  From Scientific American, March 
1949 and April 1950, by Albert Ingals.

ELLISON'S condemnation of the dry paper, dry-rouge polishing lap 
for telescope mirrors, contained in Amateur Telescope Making, 
page 868, three years ago led Father M. Daisomont of Ostend, 
Belgium, to send this department a printed polemic on the virtues of 
that ill-reputed method. From his communication the two following 
paragraphs are abstracted.

"Reverend Ellison argues that paper laps cannot be deformed and 
that they cause scratches. My mirrors show no scratches, and the 
claim that the paper, because of its thickness, renders the 
coincident curves of mirror and tool no longer the same radius by a 
gross amount is erroneous. Calculation shows that the difference 
thereby introduced is only 1/250,000-inch. The paper, pasted on the 
glass tool, is brushed shaggy with bristles and fits after a few 
strokes.

"Polishing on pitch gives good results. Polishing on paper is at least 
as good, but far simpler, cleaner, more manageable. Foucault made 
wonderful mirrors with this, his method. It can produce real gems. 
As for pitch, send it to the devil. It will then be in its element."

In January, 1947, this department, seeking only the facts, published 
a theoretical refutation of Ellison's claim that a sheet of paper throws 
mirror and lap out of coincidence by the amounts he indicated. The 
amount proved to be about the same as Father Daisomont had 
stated. This department then invited him to furnish instructions for 
the paper lap, together with a small sample of the paper he used. 
These were received two years ago. He wrote, "I send the exact 
description of how we prepare and use paper laps.

"It is essential to use paper of excellent quality, pure, without 
defects, unsized. We think well of duplicating paper 1/10-millimeter 
thick. Make flour paste of soft consistency and strain it through fine 
linen to avoid lumps. Clean the tool, rub on a light, uniform layer of 
paste. Rinse paper in water, remove excess water between blotters, 
lay it at once on the tool, and roll out excess liquid with hand or 
roller. With a knife tip remove any hard grains in the paper.

"When it is dry, cut around it with a razor blade, leaving a millimeter 
to fold down. With an old toothbrush rub the paper to raise a light 
down. With the hand put on a very little dry rouge, uniformly. 
Remove surplus rouge with a toothbrush. The rouge layer should be 
so light that the paper may easily be seen. If too thin during work, 
add a little rouge."

Copies of these instructions, with little samples of the Belgian paper, 
which a New York paper manufacturer has called ordinary 
mimeograph paper, have been sent from time to time in the past two 
years to approximately 25 individuals and groups in the U. S. Most 
of these declined to make the test. Some of them pointed out that in 
Amateur Telescope Making Ellison had already settled the matter. 
However, several did try the paper lap.

In July, 1947, John M. Holeman, of Richland, Wash., reported: "The 
paper lap is fast but gave a 'lemon-peel' finish, though not so bad a 
one as a felt lap. Under test my mirror, polished four different times, 
looked like blistered paint or ripple glass. The figure is easily 
controlled with paper. Turned-down edge is not so bad as with the 
soft pitch many use. The drag is great and a 10-minute spell of 
polishing takes a lot out of one. After fine emery I polished in half an 
hour. The lap is so fast that it is hard to figure with it.

"Making the lap conform is the chief difficulty. Despite theory, the 
paper's thickness or something does distort the curve and the edge 
polished first. This can be handled by watching for it and buffing 
down the lap with a suede leather wire brush-at the cost of as much 
work as channeling a pitch lap."

In March, 1948, J. J. Peabody and Dale Bufkin, of Elgin, Ill., 
reported: 'We strongly suspect that 'Daisomont' is Albert Ingalls in 
disguise! We battled as follows. With a six-inch f8 mirror we tried 
eight grades of paper from .002- to .008-inch thick. We polished 180 
hours on our machine at various speeds and under pressures 0 to 
25 pounds, the lap eight inches in diameter. Also tried it three hours 
by hand. Extreme caution is needed to avoid scratches. We tried 
rouge, cerium, Barnesite. In every case, gross lemon peel showed 
under test. On a pitch lap this vanished at once. Back on the paper 
lap it reappeared. From theory, you admitted Ellison's error about 
the fit of curves, but in practice he is right; they just don't fit. Radius 
of outside zone came out 12 inches longer than central zone."

W. A. Calder, professor at Agnes Scott College, Decatur, Ga., 
reported: "Tried three times to polish, using mimeograph paper, 
Scott tissue; rouge, Barnesite, dry; then with kerosene, again with 
turpentine. Results inconclusive. I finally broke down and put the 
mirror on a pitch lap, which did wonders in a few minutes."

Rudolph Moulik, of Cicero, Ill., reported that the paper lap seemed 
to be good when tested on two four-inch convex surfaces. However, 
since convex shapes cannot be tested by the Foucault method, the 
state of the surfaces could not have been studied. He attached the 
paper with thin varnish and found that it was difficult to keep good 
contact. He polished with Barnesite.

Shown some of these reports, Father Daisomont replied in 
December, 1947: "There is certainly something wrong with the work 
of your American friends." His claims, many of them so emphatic 
and extensive that there is not space to repeat them here (our 
Daisomont file is now an inch thick), do indeed point toward the 
conclusion that somewhere there is a large discrepancy; especially 
in view of the fact that in one of his 11 letters he mentioned that he 
had just polished and figured a six-inch f8.5 mirror in 10 hours on a 
dry paper lap and that it showed the image of Saturn very well at 
350 diameters.

Therefore this department will pursue the discrepancy further. To 
that end it has asked Father Daisomont for a little of his rouge and 
enough paper for a lap, and will try to follow his instructions without 
the slightest deviation. (It has also sent him Garnet Fines and told 
him that after the* use, glass on glass, not only the large type 
named by Ellison in ATM, page 79, but the text type of ATM could 
be read through the mirror, dry, held seven inches below the eyes 
and seven inches above the page; also that Barnesite, likewise 
sent, would then polish the mirror on pitch, its sinful disposition 
atoned for by speed and its fragrant aroma, in two hours.)



IN March, 1949, this department described experimental attempts 
several American amateur telescope makers to polish mirrors on 
paper lap None turned out well. One worker r ported that these laps 
gave heavy drag. The figure was easy to control, but co tact was 
hard to maintain, and the surfaces produced were "lemon peel. 
Another worked 180 hours, using a machine, but always obtained 
lemon-peel surfaces. A third had contact troubles Yet Father M. 
Daisomont of Ostend Belgium, the leading exponent of the paper 
lap, stated without hedging that a six-inch mirror he polished with 
rouge in 10 hours on a dry paper lap showed Saturn's rings well at 
350 diameters. Regardless of long-standing dogma about the 
inferiority of paper laps, this statement remains as a challenge to be 
not merely disproved but investigated objectively.

None of the experimenters followed Father Daisomont's working 
directions. I tried to do this, and experienced no troubles with 
contact, scratches or lap. The directions follow.

Use common, rough, unfilled mimeograph paper of the kind 
available at an commercial stationer. Cut out a rough circle an inch 
or so larger than the tool. Dilute white library paste until sloppy and 
smear it on the tool with the fingers, using a minimum covering 
amount. Dip the paper in water, lay it for a moment between 
blotters, and then place it on the tool. Smooth it out and leave it to 
dry for a while with no mirror on top. When the paper is finally dry, 
trim off nearly all the overhang with a razor blade.

Dab a dry wad of tissue or rag in dry rouge and dab this on the lap. 
Instead of attempting to spread it evenly, which may result in too 
much rouge, dab it in evenly distributed blotches, which will spread 
under work. If the lap remains red instead of pink after a little 
polishing, with paper showing through white, make another lap. To 
remove the old one soak it a minute and scratch it off with the 
fingernails.

An important source of satisfaction with a paper lap is the ease of 
making another, so that there is no reluctance, as with a prized pitch 
lap, to destroy it. It also permits resumption of interrupted polishing 
with no preliminaries whatever. To those who do not enjoy the 
fragrance of hot pitch, or who are repelled by lovely messes, or find 
pitch possessed of seven devils, the paper lap is a lily-handed 
escape.
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