20 May
2002
20 May
'02
11 a.m.
Since we are talking about scratched glass, do you
have any ideas on how to remove scratches from the
face of a CRT?
I use Jewelers rouge I got from a Jeweler friend many
years ago. It works well on surface scratches such
as those you get from laying the monitor on the tube
face.
Lee.
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20 May
20 May
11:19 a.m.
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1:08 p.m.
On Tue, 21 May 2002, Tony Duell wrote:
Any particular grade of rouge? I've got a couple
of lenses with minor
scratches that would probably benefit from gentle polishing. But the
jeweler's catalogue I've just looked in (H.S. Walsh) lists about a dozen
polishing compounds, none specifically for glass. Or doesn't it matter
too much? Jeweler's rouge is amongst them (and is not too expensive).
That'll depend on the depth of the scratch and how much elbow-grease
you're willing to invest. :)
Generally, I'd treat it as a lapidary repair, because it is.
First, trying to treat a deep mar with a finish-grade abrasive is an
exercise in futility.
Choose the grade of abrasive _just_ finer - maybe 2 grades - than the
blemish itself. Remove the scratch, leaving a lot of finer scratches.
Go to the next finer grade - or skip one - of abrasive and polish out
the aforementioned finer scratches.
Repeat. Be careful to gradually expand your coverage. A very smooth,
but very sharply graduated, indentation in the surface will be as
distracting as the original blemish. Spread the low spot out.
Use abrasives suited to the material. For example, Red Rouge is a
metal polish. It _will_ eventually polish glass, but there are better,
faster abrasives. Chromium Oxide comes to mind. Diamond grits are not
as expensive as you'd expect, and your local custom jewelry shop might
sell you the little dab you need.
Most any good lapidary catalogue will have charts of the grades and
applications of their polishing compounds.
Doc
21 May
21 May
12:04 p.m.
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2:05 p.m.
On Wed, 22 May 2002, Tony Duell wrote:
Either. Chromium Oxide is used for slightly softer stones (ie
not quartzites), is considerably cheaper, and doesn't stain _nearly as
badly. Cerium oxide is The Biggest Mess Known To Man.
Use
abrasives suited to the material. For example, Red Rouge is a
metal polish. It _will_ eventually polish glass, but there are better,
faster abrasives. Chromium Oxide comes to mind. Diamond grits are not
Is that Chromium oxide? Others have suggested Cerium oxide (which I do
recall is used) Thanks for the tips
You're very welcome. I try never to miss a chance to show off.
I meant also to mention that you might not want a mirror finish. The
finish on this display looks more like a semi-matte.
Doc
22 May
22 May
11:26 a.m.
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2:06 p.m.
On Thu, 23 May 2002, Tony Duell wrote:
I have found Cerium Oxide listed in the Walsh
catalogue -- it's not _too_
expensive (\pounds 17.00 or so a kilogram, but I asume a kilogram will
last me for years). I can't find chromium oxide...
Should it be listed by grade (particle size)?. The catalogue I have just
lists one grade (and doesn't say what it is). I really need to find an
optical place...
Nah, after you get past the finer diamond pastes, the gradation is
in the compound itself, not the particle size.
Why? IIRC Cerium oxide is a white-ish poweder.
Chromium oxide is green,
isn't it? Anyway, they can't be as bad as toner (and yes, I have rebuilt
toner cartidges myself...)
Yes, I've been corrected 4 or 5 times now. Chromium oxide is the
green one. And yes, it's about as pervasive and more permanent than
toner. The color is also much more revolting.
I assume I use it in as clean a room as I can manage,
but far from any
delicate machinery (that is going to be the problem -- there are
precision machines, etc everywhere round here). Abrasives and fine
engineering do not mix. One book I have on experimental techniques covers
lens grinding. It says something like 'A lathe is essential. But don't
try to grind your lens on a metalwork lathe, for all it would do the job.
The lathe is for making the tools and the mountings for the lens. There
is no quicker way to ruin a lathe than to use abrasives on it. And there
is no quicker way to ruin your lens than to drop it on the lathe bed'.
You're also going to want lap discs for each grade, and wash
_everything_ between stages. A couple of times.
Hrrm. I've done a little work with leaded crystal, and some with
bottle glass. Enough to tell me there are as many hardnesses and types
of grain to glass as there are to wood. Since i don't know anything
about optical-grade glass, I'm demoting myself to looking over your
shoulder.
Doc
8298
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