Took 20 years off my windshield!!

[PaulE]

I tried the cerium oxide powder on my daily driver back in the early fall. I used the glass polishing pads like jakeru, but with my Porter Cable random orbital polisher. It isn't dual action, only random orbital. I did not spend a lot of time on the windshield, but it didn't look like I made much progress on the thousands of tiny specks in the glass from road grit. I don't have issues with marks from my wipers, just the specks since I do all my driving on highways and the daily driver has 93,000 miles already. So, here's my multi-part question-If I spend more time on the windshield, can I expect to make any improvement on the tiny specks? And if so, do I need to use a polisher that isn't a random orbital motion? And if the random orbital polisher should do the job, should it be at a higher or lower speed?

[Lew]

I would think a firmer pad and higher speed with more downward pressure. Others might agree.
However it's your call.

[BoxsterSteve]

Originally Posted by PaulE

Can I expect to make any improvement on the tiny specks?

Not likely. I've investigated this for my own DD.
When there are actual chips out of the glass, polishing will never remove enough material to make a noticeable improvement.
Time for a new windshield.

[PaulE]

Originally Posted by BoxsterSteve

Not likely. I've investigated this for my own DD.
When there are actual chips out of the glass, polishing will never remove enough material to make a noticeable improvement.
Time for a new windshield.

Thanks, then I'm waiting. I know that if I get a new windshield, a rock will find it!

[jakeru]

Originally Posted by ArizonaDan

@jakeru depending how badly your windshield is marred, it may take quite a bit longer than 20 minutes.....I had some heavy wiper blade marks on mine....took me closer to 1 1/2 hours as I worked in small sections...about 2 ft square....buff...clean the section...evaluate...repeat as needed while viewing from all angles to ensure you got all the marks.

no distortion afterwards.

Originally Posted by Jthoms1

Agree with Dan....mine was far quicker but it could take you longer. No distortion just beautiful clarity.

FYI, guys, after driving around with the half-polished windshield, I've come to realize the polishing operation actually has added some distortion, which is a contrary result to what you said above.

I suspect it's done it for you other folks who have polished, but just not to a severe enough degree that it's been noticeable to you guys. If I polished my whole window so I didn't have two adjacent alternatives (unpolished vs polished) to compare, I may have not noticed it too. It's a bit subtle, to the point it would even be challenging to capture with a photo.

But if you want to look for the degree of distortion through the windshield, the best way to notice it is to find a perfectly straight feature on the other side of the glass (like straight edge of a highway median), look at it through manually polished vs unpolished surfaces. Through unpolished, oe Porsche glass, (very good quality in terms of being distortion-free, by the way, especially considering its varying curves) the straight feature appears, well, straight; but through the manually polished surface, well, I'm noticing that same feature gets a bit "wavy" on mine. Most noticeable when your face isn't right up close to the glass, in fact, it might be easiest to observe from the outside of the car, looking all the way through it glass canopy to the other side.

As the cause of this is basically uneven material removal across the optical surfaces, I do wonder if using an interface pad between the relatively thin/stiff rayon polishing pad and the backing plate, and perhaps using less pressure may have allowed a bit more even material removal.

[jakeru]

Originally Posted by PaulE

It isn't dual action, only random orbital.

Hi Paul - if you didn't glean from the link Gelbster posted already, "random orbital" polisher is another name for "dual action" polisher. Basically, it oscillates in small circular motion, while allowing the pad to rotate freely. The small oscillations help keep the edge from digging in.

Originally Posted by PaulE

I did not spend a lot of time on the windshield, but it didn't look like I made much progress on the thousands of tiny specks in the glass from road grit. I don't have issues with marks from my wipers, just the specks since I do all my driving on highways and the daily driver has 93,000 miles already. So, here's my multi-part question-If I spend more time on the windshield, can I expect to make any improvement on the tiny specks?

Yes, I also noticed those "specs" in my glass as I was polishing my windshield. As BoxsterSteve said, the very fine abrasives and polishing techniques described in this thread aren't aggressive enough to have any significant effect on those.

Originally Posted by PaulE

And if so, do I need to use a polisher that isn't a random orbital motion? And if the random orbital polisher should do the job, should it be at a higher or lower speed?

A rotary polisher is generally the most aggressive polishing tool. The drawback is the relatively fast-moving edge can easily "dig in", making even removal of material more of a challenge. However, I think the issue for pock mark removal is too fine of an abrasive.

Personally, when using a dual-action/random orbital, I like the speed set low enough that it doesn't sling material. By controlling downward pressure, you can influence cut rate. Running things at higher speeds, or too much downward pressure, can also input more heat into things, which can be problematic if things get too hot. In my case, I managed this heat by re-misting with water from a spray bottle a few times.

I have a set of diamond polishing pads for polishing stone/granite countertops, that are designed to use with rotary polishers, and ideally, flooded with a constant flow of water, as both a coolant and to keep freshly removed grit removed. While it would be an interesting experiment to try using them to polish automotive glass, and I'd be fairly confident they could break through at least some of those "pocks", I'd be very fearful that attempting this may result in uneven material removal (more likely the more aggressive you get with removal). You could easily make things worse (inducing optical distortions/aberration) than just leaving the small pits! Not to mention the time and effort required compared to the alternative of replacing the windshield.

You might look into some sort of windshield chip-filling resin might be workable to fill your pock marks, but I can't say whether it'd be worth the effort or not. Typically the chip-filling resin is done one chip at a time, and is UV-cured. The excess resin can be mostly shaved off flat with a razor blade afterward.

[PaulE]

Originally Posted by jakeru

Hi Paul - if you didn't glean from the link Gelbster posted already, "random orbital" polisher is another name for "dual action" polisher. Basically, it oscillates in small circular motion, while allowing the pad to rotate freely. The small oscillations help keep the edge from digging in.



Yes, I also noticed those "specs" in my glass as I was polishing my windshield. As BoxsterSteve said, the very fine abrasives and polishing techniques described in this thread aren't aggressive enough to have any significant effect on those.



A rotary polisher is generally the most aggressive polishing tool. The drawback is the relatively fast-moving edge can easily "dig in", making even removal of material more of a challenge. However, I think the issue for pock mark removal is too fine of an abrasive.

Personally, when using a dual-action/random orbital, I like the speed set low enough that it doesn't sling material. By controlling downward pressure, you can influence cut rate. Running things at higher speeds, or too much downward pressure, can also input more heat into things, which can be problematic if things get too hot. In my case, I managed this heat by re-misting with water from a spray bottle a few times.

I have a set of diamond polishing pads for polishing stone/granite countertops, that are designed to use with rotary polishers, and ideally, flooded with a constant flow of water, as both a coolant and to keep freshly removed grit removed. While it would be an interesting experiment to try using them to polish automotive glass, and I'd be fairly confident they could break through at least some of those "pocks", I'd be very fearful that attempting this may result in uneven material removal (more likely the more aggressive you get with removal). You could easily make things worse (inducing optical distortions/aberration) than just leaving the small pits! Not to mention the time and effort required compared to the alternative of replacing the windshield.

You might look into some sort of windshield chip-filling resin might be workable to fill your pock marks, but I can't say whether it'd be worth the effort or not. Typically the chip-filling resin is done one chip at a time, and is UV-cured. The excess resin can be mostly shaved off flat with a razor blade afterward.

Thanks for your detailed response. These specks in my windshield of my daily driver, and also in my Boxster, are very small, and there are lots of them. When the windshield is clean, and I'm driving into the sun, it can sometimes be like looking through a galaxy of stars in the sky on a clear night. It's annoying but not the end of the world. If I'm not driving into the sun, if it's raining, or night time, you can't see these specks. You can barely feel them if you run a finger nail over them. I'm going to try again in the Spring, first on the daily driver. If I get some improvement, great, but if not, I'll leave it alone until the time comes that I need a new windshield. I appreciate the advice and things I learn here!