About 8 months ago I tried to correct my badly scratched windshield with a PC 7424, CeriGlass, and Lake Country 5" Glass Polishing Pads. The windshield is original on my 2001 Nissan Pathfinder. I bought the vehicle used, but it's still the factory Nissan glass. Twelve years of running windshield wipers on dirty glass left the windshield in bad shape. You can see my original attempt here: Ceriglass My Experience
To sum it up, while my first attempt did clean the glass up, it left hazing, tic marks, and micro marring on the glass. As time went by, it became more annoying and noticeable I was considering replacing the windshield, but I really wanted to learn how to fix glass, as wiper scratches on a daily driver are probably inevitable. Why did my first attempt to fix it fail? Was it:
1. CeriGlass is no good?
2. The fault of the LC Glass Pads?
3. That you need a rotary to remove scratches from glass and the 7424 wasn't cutting it?
4. My fault?
5. A combination of all the above?
For the past 8 months or so, I've been trying to figure it out. The problem is, there is a lot of info (and products) geared towards cleaning and removing water spots from glass, but not too much info on how to remove defects or scratches from a glass windshield.
Here are some pictures from both my original and latest experience with glass polishing
Here you can see some blur and wiper scratches looking out from the inside. The tic marks / micro marring I was not able to capture with my camera (IPhone 5):
More wiper scratches:
This time I picked up a new DA, a GG6, and figured the increase power would help. Also, I decided not to use LC Glass Pads, as the old ones started falling apart while I was using them once they got wet. Since CarPro makes CeriGlass, I figured their pads would be ideal. Also, they come in 3" & 5". The CeriGlass I received this time seemed more lotion like than the product I bought 9 months ago. Also, the color was a yellowish off white. The older CeriGlass was like White Out. Here are the two to compare :
As soon as I got the CarPro glass pads, I realized they were different. They were not just re-branded Lake Country glass pads, as I suspect a few others are. In fact, they are significantly different. CarPro advertises them as rayon glass pads, I'm not sure what the LC pads use for the cutting material, but those pads are very stiff, almost cardboard like with no cushion. I found that the cutting material on the LC seems to be attached to their pads with some sort of adhesive. When it gets wet, they start to shed cutting material.
Not so with the CarPro pads. Actually, when this was all done and the pads were washed, the CarPro pad looked like new still. I was able to do this whole job with just one CarPro pad of each size.
Here you can see the CarPro pads (thicker with red Velcro) vrs. LC's glass pads:
The CarPro pads are thicker, flexible, and have more polishing material (rayon) more densely packed on the face. I was starting to think this actually may work, as one of the main issues I had previously with the LC pads is the polishing material coming off the face of the pad when you spray them with DI water while polishing (after a while).
CarPro 3" Pad
Polishing with CeriGlass makes a huge mess, as the polish must be kept wet through frequent sprays of DI water on the glass. I found no matter how hard you try to cover up the vehicle, washing the car will be required after you are done machine polishing with this stuff.
Towels were taped to the hood and the roof. Also, paper was taped to the side glass. The good thing is, CeriGlass is water based, so it comes right off with the spray of a pressure washer.
A picture of my set up:
From L to R: GG6 DA I got from AG just for this project with 3" LC BP & 3" CarPro Glass Pad, LC 5" Glass Pads, Meg's Mild Mirror Glaze Clay, CarPro 6" & 3" Rayon Glass Pads (red Velcro), DI water in spray bottle, isopropyl 25% in a spray bottle, CeriGlass Polish, Prima Clarity Glass Cleaner, and CarPro Fast Glass cleaning cloth.
1. After covering up as much of the vehicle as possible, I cleaned the windshield using Prima Clarity. After that, I clayed it using the Meg's clay. Not much came off. Then, I wiped it all down with a 25% solution of IPA. Interestingly enough, I had the window coated with the new Pinnacle Glass Sealant. Neither the clay or the IPA seemed to remove any of it. I thought the clay would for sure, but it didn't touch it. Windshield was beading after as well as before cleaning.
2. After cleaning, I decided to start with the 3" CarPro pads on a section with the worse scratches in the bottom portion of the wiper path. This is where I started:
While the scratches don't look too bad in the photo, they are MUCH worse in person. You could just barely catch your nail on them if you tried. I decided to start with the small pads and work on a small area, about 8" x 14". I began by priming the pad and placing about twice the amount of polish on it than usual for paint polishing.
I turned the machine on about speed 4.5. I was able to make ONE pas before the polish started to dry. However, I was prepared for this and had my DI water in a squirt bottle at hand. I soon realized that I was going to have to spray a squirt or two of water on the polishing surface after EVERY pass to keep to polish "wet".
This is possibly where I may have went wrong last time. This is nothing like polishing regular paint. The polish dries extremely quickly on the glass surface. It's very important (I found out) to NOT let the polish dry at all while buffing. This can get a bit difficult. As your constantly one handing the buffer to reach for your spray bottle. Also, the pads have little backing material between them and the backing plate (they are as thick as two stacked pieces of cardboard), so this causes a lot of vibration and make the polisher a little hard to control at times.
After a few section passes, and several squirts of water, I decided to kick the polisher's speed up to 6. I was using very slow arm speed (about 1/2" per second) and putting a lot of downward pressure on the polisher. Three things I noticed fairly quickly about the process/ products:
1. The pads did not heat up at all, in fact they stayed cool. This was due to the constant spraying of water to keep the polish "wet". Once the pads got saturated with polish and water they became very flexible and you were able to bend them in half if off the backing plate. The pads would stay damp, but the polish would dry on the glass surface. This is contrary to the LC pads, which always stayed firm.
2. The CeriGlass has an almost an infinite work time when spraying it with water. To complete the whole windshield I ended up using less than 1/8 of one small (4 oz?) bottle of CeriGlass and likely could have used less. This is contrary to my last attempt, where I kept adding more and more polish as it would dry (and some water) and ended up using over half the bottle for one attempt.
3. The "overheating issue" some have experienced when using the Griot's GG6 DA Polisher is not cause from heat transfer from the polisher motor or mechanism. Any heat is directly transferred from the buffing pad to the backing plate. The machine itself creates little if any heat. This became significant because often times during this session I was running the polisher on SPEED 6 with lots of down pressure for up to 20 minutes strait without shutting the polisher down. I kept touching the guard around the spindle mechanism and it stayed room temperature.
After about 15 minutes of buffing that small area, I stopped to check my progress. I was really happy to see the scratches were 100% gone and the glass was optically clear - no hazing, tic marks, micro marring - just clean, clear glass.
Same Area After:
After the initial spot, I decided to switch over to the 5" CarPro pads, as it took quite a while to do that small area. Also, I was running the buffer at full speed and it sometimes became difficult to control and keep grabbing the water bottle, since the pads have little cushion. This is where the bale handle on the Griot's Polisher actually came in handy.
To do the complete windshield, I ended up spraying almost a full liter of water. I probably used less than 1 ounces of polish. The total polish time was probably about 2.5 hours, where, the buffer ran at full speed for 20 minute increments without breaks under a lot of downward force. The Griot's machine performed perfectly.
I was able to remove pretty much all the scratches and tic marks from the glass just from repeating the process over and over. In fact, I feel I would have been able to remove even deeper scratches then were present with more polishing time. Unlike paint, with glass you don't have to worry about strike through. There are still some pits in the glass and they can not be removed.
Some pictures of the process:
Here is what I learned about glass polishing with this combo:
1. The CarPro pads are like night and day compared to the LC glass pads. The CarPro pads don't fall apart after prolonged buffing in the wet polishing slurry. They are thicker, and they have denser polishing material on the front. I would recommend the CarPro Rayon Glass pads to anyone trying to remove defects from glass. Same thing with Ceriglass. Both are first rate products that really have no competition in my mind. While there are a lot of "water spot removers"; I don't know of any other available glass products that claim to remove scratches from glass, no less one that can actually do it.
2. You do not need a rotary to remove scratches or defects from glass. In fact, a DA could be better, as you will not have to worry about heat build up or causing any type of holograms in the glass - assuming its done correctly.
3. Adding water to Ceriglass (keeping the polish "wet") while polishing is essential to success. Plan on spraying after every section pass - it dries that fast. In fact, I'm convinced dry buffing contributed to my hazing the first go around. This can not be stressed enough. You need very little polish and a lot of water. This is opposite to regular paint polishing, where you may add a single spray of water to a compound to boost the work time. Also, you get more done by adjusting your process. When doing a single pass, I would back up and go over the line I just worked, since the polish was still wet their. Once I was at the point to add more water on that line, I would move to the next pass.
4. Working with the 5" CeriGlass pads is much easier than the 3" pads. Nothing is wrong with the 3" pads, its just a function of their size - its hard to control the machine with the 3" pads, since there is little flexible interface to the pad, the machine sometimes wants to walk or tip. Moving the buffer with one hand did not work well, so I was quickly hugging between the water bottle and keeping both hands (and a lot of downward force) on the polisher. The 3" pads would be good for small areas of glass and corners where the bigger pads won't fit.
Here are some pictures of the glass when finished:
From the inside looking out:
After I was done I did a final clean on the glass with a CarPro Fast Glass Towel:
This towel is very thin (140 gsm) and kind of reminded me of a thick white shop towel or a square of bed sheets from a cheap motel. It's meant for removing any streaks or haze that is often left after cleaning glass conventionally. You use it only with water. It works very well, much better than a regular towel. While any other towel wet with water would leave rows of water streaks behind, this towel leaves what looks like a fine mist of water that instantly evaporates. Anyone who struggles getting the inside of the windshield perfectly streak free should get at least one of these for 5 bucks from CarPro USA. They also work great on your bathroom mirror.
After I was done with the glass I rinsed down at the local coin-op and did a waterless wash with Pinnacle Liquid Crystal Waterless Wash:
The wheels were cleaned with a Montana Boars Hair Wheel Brush, a Daytona Brush, and Chemical Guys Sticky Wheel Cleaner. Then I spray waxed with Flitz Wäxx Speed Wax Spray - a great spray wax that doesn't streak - even on glass. All the glass was also waxed this way (except the windshield). This vehicle has a lot of glass!
Thanks for looking and feel free to ask any questions.