Polishing scratches out of glass?

Youngest son just got his first (used) car. It seems to be working well
after his first month of ownership but it has an annoying visible
whitish arc about 1/16" wide on the passenger side of the windshield
caused by a broken wiper blade assembly which was dragging metal over
the glass. Said blade was on the car when he got it. (Why some people
will drive a car and ignore stuff like a busted wiper blade is what
separates us type of folks from the rest of the world.)
I remember when I was a kid (circa 1950) there used to be traveling
glass polishers who'd make the rounds of car dealerships and spruce up
the used car's windshields on the spot by polishing out scratches like
the one on son's new (to him) car. I expect those guys have gone the way
of the dodo by now.
IIRC they used cerium oxide with a felt buffing wheel in a drill motor
to work their magic.
I'd like to help my son fix that scratched line, it has insignificant
depth, and it's out of the passenger's straight line of vision, so a
perfect surface isn't required. Can someone here confirm that cerium
oxide is the the stuff to use and suggest a good place to buy a small
quantity and some suitable buffing wheels. Or, tell me what's being used
for polishing glass nowadays.
Thanks guys,
Jeff
Reply to
Jeff Wisnia
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What I've used is toothpaste. I always have some in the house, and it is a fine abrasive which does a good job polishing glass.
But if you want the real thing, this place
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cerium oxide for $10.60 a pound. A pound will last you a long long time.
Use a hard felt wheel. You want a SFM of about 1100 for glass polishing. Pro machines use a 10 inch wheel turning fairly slow to get 1100 SFM, but that's not going to be handy for doing a windshield in place.
HF has small felt bobs on 1/4 inch shafts, 3 for about $3. Just chuck one up in a drill motor and go to it. Dremel has polishing bobs for their tools too, but they're awfully small for a job like this.
Gary
Reply to
Gary Coffman
At one time, J.C. Whitney had a polishing kit, had cerium oxide and some felt bobs. Don't know if it's still available. I asked an auto glass out fit once, they don't do scratch polishing, they'd rather sell you a new chunk of glass.
Stan
Reply to
Stan Schaefer
Thanks. I got tipped off my someone else who read my post that JC Whitney sells a glass polishing kit with a 3" diameter by 2" thick 1/4" shafted buffing wheel and 8 oz of cerium oxide. I just ordered one.
At $29.99 it's a bit pricey, but WTF, I've got to learn to put put things in perspective and as it now costs over $20 to park a car for two or three hours in downtown Boston, or even Cambridge, how can I pinch pennies over something to use on my youngest kid's first car?
Plus, I can probably remove some of the haze from the windshield of SWMBO's '98 buggy, which annoys me whenever I happen to drive it at night and the lights of oncoming cars make me feel like my eyes have suddenly gotten cataracts.
I became more concious of that effect last week when the windshield of my own 10+ year old buggy got cracked by a pebble tossed up by a truck.
After the insurance company bought me a new windshield, there was no longer a haze of fine scratches being illuminated by street lights and oncoming headlights right in front of my eyes. The difference (excuse me) is like night and day.
Jeff
Reply to
Jeff Wisnia
||Gary Coffman wrote: ||> ||> Use a hard felt wheel. You want a SFM of about 1100 ||> for glass polishing. Pro machines use a 10 inch wheel ||> turning fairly slow to get 1100 SFM, but that's not going ||> to be handy for doing a windshield in place. ||> ||> HF has small felt bobs on 1/4 inch shafts, 3 for about $3. ||> Just chuck one up in a drill motor and go to it. Dremel has ||> polishing bobs for their tools too, but they're awfully small ||> for a job like this. ||> ||> Gary || ||Thanks. I got tipped off my someone else who read my post that JC ||Whitney sells a glass polishing kit with a 3" diameter by 2" thick 1/4" ||shafted buffing wheel and 8 oz of cerium oxide. I just ordered one. || ||At $29.99 it's a bit pricey, but WTF, I've got to learn to put put ||things in perspective and as it now costs over $20 to park a car for two ||or three hours in downtown Boston, or even Cambridge, how can I pinch ||pennies over something to use on my youngest kid's first car? || ||Plus, I can probably remove some of the haze from the windshield of ||SWMBO's '98 buggy, which annoys me whenever I happen to drive it at ||night and the lights of oncoming cars make me feel like my eyes have ||suddenly gotten cataracts. || ||I became more concious of that effect last week when the windshield of ||my own 10+ year old buggy got cracked by a pebble tossed up by a truck. || ||After the insurance company bought me a new windshield, there was no ||longer a haze of fine scratches being illuminated by street lights and ||oncoming headlights right in front of my eyes. The difference (excuse ||me) is like night and day.
I know a guy who road races a production-based sports car. whenever he does an enduro that includes night racing, he always has a new windshield installed immediately before the race (even when co-driving someone else's car). He says the added clarity gives him an edge at night.
Texas Parts Guy
Reply to
Rex B
cerium oxide is commonly used for the final polishing of cold worked glass pieces. Should you need more you could enquire on rec.crafts.glass for local suppliers, or ask at local glass studios or abrasive suppliers. I believe it may also be used in lapidary.
Jeff Wisnia wrote:
Reply to
David Billington
Yep. Should be able to get it at any glass place. Certainly will be available at any rock/lapidary store. Costs vary but around $9-10 per pound. You probably need less than 1/2 ounce. Felt or muslin wheels for your drill are ok, but muslin on a polisher would be easiest way. Make a slurry of some cerium oxide, damp wheel/polisher, and add some slurry from time to time. Won't be fast.
Reply to
George E. Cawthon
All this makes me wonder:
Every time I go to the optometrist with scratched up lens and say, "Hey doc, can you polish out these scratches for me?" He goes, "Errrr, welll, no. We can't do scratches. But I can cut you a new pair for $395."
Bob Swinney
Reply to
Robert Swinney
Windshields are a bit farther away from your face, and minor optical aberrations can be allowed. Glasses would give you a serious headache if the polishing put an aberration in them - it would be like looking through a distorted funhouse mirror all day.
They could set the lenses up in the machine that ground them originally and buff out all those scratches the right way - but there are two big problems: One, nobody hand-grinds lenses locally anymore. and Two, the machines are setup to work on round blanks, not the cut lenses.
They order the blanks pre-ground from a national optical supplier, and the only machines I've seen at the local labs are to grind the lens edges down to fit in the frames.
-->--
Reply to
Bruce L. Bergman
Ack... managed to hit the "r" (reply) and "e" (Send) keys at the same moment, so it started the reply, then instantly posted it before I had a chance to type anything. That'll teach me to post before my fingers have had their second cuppa coffee! :)
Anyway, I was going to say that you're working with two different situations - THe OP wants to take haze out of a windshield. Effectively, he's working on a piece of glass that's "flat" as far as optical behavior is concerned.
Your eyeglasses aren't "flat" - They're *VERY CAREFULLY* curved, depending on exactly why you wear them, they might have *VERY* precisely placed compound curves, sections where there are numerous, parallel "prisms" that are individually invisible, and other strange "features". Altering the curvature in any way, either flattening it, or increasing it, can (and probably will) create shockingly large changes in the optical properties of the lens for even a tiny amount of physical change.
Since your glasses are supposed to be correcting flaws in your eyeball's optics, that's going to play hell with your vision. A flat (relatively speaking) windshield is much less critical - It IS possible to overdo the "unscratching" process, but in this case, the "lens" is so large, and the curvatures involved are so small (comparatively speaking in both cases, of course) that any curvature you're likely to add/subtract is going to end up "lost in the background noise" - You're unlikely to ever notice it without deliberately trying to spot it, and maybe not even then without the use of precision measuring instruments.
So yeah, it is a "scam" of sorts by your optometrist - It's cheaper for him to cut you a new set of lenses than to try to deal with your complaints of headaches, fuzzy vision, and whatever else may come of your prescription being changed in the "unscratching" process. And you'd probably scream "Scammer! Why didn't you tell me this was gonna happen?!?" even louder when you finally got to the point where you gave up and said "just make me a new pair".
Reply to
Don Bruder
On Sat, 28 Aug 2004 15:48:38 GMT, Don Bruder vaguely proposed a theory ......and in reply I say!:
remove ns from my header address to reply via email
Isn't the scam in th4e fact that you pay $50 for the lens and the rest for the frames?
Seriously I know somebody who went to the local store, bought a pair of sunnies for $20, then went to the optomterist and said "I want my lenses in these frames" (and probably "please" or something), and paid maybe another $50.
***************************************************** I have decided that I should not be offended by anybody's behaviour but my own......the theory's good, anyway.
Reply to
Old Nick
Most sunglasses are pretty flimsy compared to real glasses, especially the hinges (I'm thinking of metal frames, maybe not so much difference for the plastic ones). You can also have new lenses put in your old frames, so they can last a long time (again, thinking of the metal ones-- plastic ones don't last as long).
The spring-loaded hinges are a great invention.
Reply to
Ron Bean
The J.C. Whitney scratch polishing kit arrived yesterday and this evening I used it to make that whitish scratch go away, much to the pleasure of youngest son.
I took it easy as suggested here, and took me about a half hour to get all of that scratch out, as it spanned about half the windshield wiper sweep near the outer end of the blade. Considering the time it took me I can see why those itinerant scratch removing specialist guys I remember from my youth aren't around anymore.
We're a "throw away" society now, and the labor cost plus three or four employee insurances and all the other blessings and benefits heaped on employers by well meaning thoughtless liberals probably makes the shop owners say, "It's cheaper to get a new windshield buddy".
Thanks for the encouragement guys,
Jeff
Reply to
Jeff Wisnia

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