Polishing windshield

[AndreiC]

Somehow, I don’t know how, I managed to put an unpleasant scratch in my windshield. It is an area of maybe 1/2” x 1/2” that is now hazy, and if you feel it with your finger you can clearly feel it’s not smooth (it’s on the outside).

Can something like this be polished out without messing up the whole windshield? I can live with it as it is, but it is in my field of vision and it will bother me every time I fly. But replacing the whole windshield (which probably is at least a 1 AMU endeavor, if not more) sounds stupid for such a small scratch. 

I was hoping that maybe the kind of treatment that removes haze from car headlights would fix it. But I don’t know if it works, if it does not make it worse, and if I can do it in just one localized spot or if I need to polish the whole windshield. 

[PT20J]

Try Novus plastic polish. Micro-mesh if it's too deep for the Novus. Work a much larger area than the defect to blend repair so that you don't created a wavy spot. 

https://www.amazon.com/NOVUS-PK1-8OZ-PM-Plastic-Scratch-Remover-Bottles/dp/B0029B518O/ref=sr_1_5?crid=2ACXNZG8Q3I5U&dib=eyJ2IjoiMSJ9.xhC6gaULd5ZtKOfVkF6ulyiuvtq03bY7QVM0_Fixf6ferCEsiVxOEt-l_I_3hc-336uyx_fTgst-lAti01_aS2PBia9s67VUGwORbrZpm37bTtCF96Qi9j_j1K3b6KYcAPwaEHFQPfWhh1eJCMLQ37UI0vzmAeaOoboDEebZ21p19dE37utUg-ARE194AqsOi4PCb8xw8LhoDfCEdOW9qh4CxLvnpvc0HxnmYp16KnOfg3VGh8AozNcvpleDAgeI079bY4dTzCkefTZRR2_qZKmNC1FXqG1787W7wTvbn8VtLIV-BZwQmy5mVAgxD4DkLeUd5UA0DE8pY4BlrDon3yze8SrfiviT3mV-ilWHNJG0ognKrfKTpY02-WC6w8Z_kXJs5b5tcsYAYFR3WC62CtKNVuCN95gQEUhyawnjA095vZ0uAePmHD6yLeO_5Fhq.S_2wUyXcF0u5aeDXwxq7k8j0mhJu4Ax_f3Ea1i0pxZ0&dib_tag=se&keywords=novus&qid=1734479554&sprefix=novus%2Caps%2C198&sr=8-5

https://www.aircraftspruce.com/catalog/cspages/micromeshstd.php?clickkey=11681

[IvanP]

I used the polish kit from Spruce on mine and it worked quite well.  

https://www.aircraftspruce.com/catalog/cspages/scratchoff.php 

 

[Hank]

13 hours ago, PT20J said:

Try Novus plastic polish. Micro-mesh if it's too deep for the Novus. Work a much larger area than the defect to blend repair so that you don't created a wavy spot. 

This means to polish an area about 6" x 6" for your scratch. Polish deeply around the scratch, and fade it out to at least this size.

EDIT:  back when I used to polish steel, each grit would cover a larger area (to eliminate the "edge"), and for a 1" long scratch, the final polish was often nearly a foot long and several inches wide. This should work for your window, too.

[MikeOH]

24 minutes ago, IvanP said:

I used the polish kit from Spruce on mine and it worked quite well.  

https://www.aircraftspruce.com/catalog/cspages/scratchoff.php 

 

Thanks for the PIREP!  I purchased the kit a couple of years ago but have been too chicken to give it a try!

[IvanP]

I think it is a good kit. It was a bit of work, but worth it. Someone managed to make some pretty substantial marks on the inside of my windshied, probably when doing avionics work before I bought the plane. I polished all the windows in less than a day (both sides on winsheild and outside only on the rest (overspray from painting, etc.). I used small Proxxon angle polisher and that made it a bit easier to work on the inside. If you plan on using rotary tool, I suggest slow speeds and apply compounds sparingly, otherwise you will have the polishing compunds all over the place (ask how I know  ). They are pretty thin liquids. It can be done by hand, but that would involve a lot of elbow grease. I did not take and before and after pics, but I am satisified with the results, despite being quite picky when it comes to maintenace of my plane.    

[0TreeLemur]

If you can feel a scratch with your fingernail, you cannot polish it out without altering the optics of your windshield.

Auto detailers removing deep scratches in plexiglas windows will use a random orbital sander with sandpaper to remove material over the entire window to the depth of the scratch, then use successively finer polishes/pads to clear the window up.    There is a good video on youtube that shows exactly how to do it.  The problem with this is approach is that it makes the window thinner, probably not good for an aircraft windshield.  I did use this approach to remove a couple of deep scratches from one of my side windows and it worked like a charm.  It took guts to apply sandpaper to the window and it looked like holy hell after I went over it.   But the Novus polish system cleared it using a finishing pad on the random orbital.

After that I used the Novus system and finishing pad to polish all my windows, including the windshield.   Aside from that one deep scratch it looks new.   Luckily that deep scratch is on the co-pilot's side and easy for me to ignore.