polishing glass

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  #1  
Old 04-10-12, 08:03 AM
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polishing glass

Hi folks

I need to polish windshield on my pickup. Any suggestions how to do it right? Area is right in the center of the field of view, and one thing I am trying to avoid is creating a lens there as result of polishing.
Anyhow, what compounds to use? I tried paint polishing paste, did nothing.
It's superficial scratches. Apparently, my windshield has a "soft spot" and wiper blade left a "smear" across it. 100% positive, it was not arm or any metal part. Smear is about inch wide.
 
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  #2  
Old 04-12-12, 05:55 PM
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Baking soda on a damp sponge may help. So it makes a sort of paste/compound. I use it on car paint/bugs, and countertops to bring back a nice smooth shine. Cheap and worth a try.
 
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Old 04-12-12, 06:44 PM
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won't hurt trying. Thanks, Mike B.
 
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Old 04-12-12, 07:12 PM
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I doubt that baking soda will do anything on glass it is too hard. Check at auto parts it seems like I saw a kit for this(dont get one for headlights) If you dont find anythig there go to a glass shop.
 
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Old 04-13-12, 06:20 PM
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yeah, it's diamond paste.

Pro Glass Polishing Kit
 
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Old 04-14-12, 07:41 AM
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Diamond, though good, is expensive. Cerium oxide is more appropriate. You can get it from JC Whitney. To avoid "lensing", make sure you don't dwell on one spot while using the rotating polisher.
 
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Old 04-14-12, 08:11 AM
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I know. worked for several yrs as polisher.

I do not buy from JC.
 
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Old 04-14-12, 03:31 PM
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How could you ask for help and then say you were a polisher for years ?? That doesn't make sense .... Do windshields have "soft spots" ?? That seems strange....

And why not buy from Whitney?
 
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Old 04-14-12, 09:06 PM
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jewelry polisher. waaaay far from anything as hard as glass. and tried to polish visor in my polishing machine, ended with lense effect, hence previous knowledge on how bad it can end.
heck, still scratching my head over this one. I had them new banana blades installed, and it ended with a definitely scratch type smear across half driver side blade path. right where the wiper arm was attached to blade.
of course, happens to be right in the middle of FOV. I tried any cleaner I could find, till realized, it is scratches. Those who had wiper arm scraping on glass, know what it looks like - except that blade is still basically new. Have no idea. Just looks like soft spot in glass.
 
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Old 04-29-12, 02:24 PM
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OK, major disappointment.
Bought cerium oxide "glass polishing compound".
Spent about an hour yesterday and some time Friday, polishing those scratches out.
Results are miniscule. It did polish smooth glass. A little bit. Whatever was scratched, is, basically, still there.
I'll just keep driving as is. It costs me less than $200 to replace windshield, if I really need to. No need to keep piling useless expenses.
So, if you have to polish glass - prolly do go for diamond paste.
 
  #11  
Old 04-29-12, 03:35 PM
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That depends how deep the scratches are. If they're really deep, you may have to start with 400 grit corundrum (or whatever is appropriate), then polish in successive steps (600, 1000, 3 micron diamond, then cerium oxide). But then you'll have glass that looks like a funhouse mirror.

Cerium oxide works well. It's not meant to take out deep scratches. Neither will diamond. Rule of thumb is if your fingernail catches a scratch, it's too deep to polish out.

You may want to tone it down a notch. I don't know what you mean by "polishing your visor" or "banana blades". You see, I too am no slouch when it comes to polishing. I have been polishing metallographic samples for 35 years. All the local metallographic supply houses know me. I have a pretty good feel for what it takes to polish materials.
 
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Old 04-29-12, 07:40 PM
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Guess, one picture is worth 10 threads



grey line in the middle, in arc, is what wiper blade did. No, you can't catch it with finger nail. Actually, quite smooth.
Grey area on the side, in circle, is after effects from cerium oxide.
"banana blade" is what, I think, they call frameless blade.
this kind:
Rain X Latitude/Wiper Blade (5079278) | AutoZone.com

My theory is, as truck was parked outside for yrs, dirt+sap+rain=grinding compound that built up on blade. Smear on the glass is right across where center blade attachment was, so it's higher pressure area. Why it did this only on the dirver side and not on the pass side - is a mystery, that's why I think, I have glass with softer area, or something.

It's no problem to drive as is, as it shows only when incoming traffic lights shine at it. Like I said, it is not feasible, at least, for me, to spend another several hrs trying to polish it out. I'd rather replace entire windshield and stay away from those blades.
 
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Old 05-07-12, 06:21 PM
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well, it's done and over. waiting for windshield installer as I type.
I went through grits 800 through 3500. All that glass is doing is getting more and more scratched.
on ironic note, at least, I have good supply of fine grit sand paper.
 
  #14  
Old 05-08-12, 05:50 AM
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In the metallographic laboratory, we polish samples using successively smaller grit until it is optically flat (mirror finish). BUT - each time we use a finer grit, we polish at right angles to the previous polish until all traces of previous scratches are gone. This is hard to do on a large surface where you likely use a circular motion.
 
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Old 05-08-12, 05:29 PM
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just like we did with gems at the factory I worked at. well, headache is gone now.
 
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Old 05-12-12, 02:15 PM
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I woulda driven to a glass warehouse during lunch hour and asked one of the workers if they wanted to make a quick twenty. In ten minutes the glass would have looked like new.
 
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