Guy Buchanan

Joined: 16 Jul 2006 Posts: 1204 Location: Ramona, CA
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Posted: Mon Jan 01, 2007 5:48 am Post subject: Removing Scratches from Windshields |
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This is a cross-post from the Lancair list. I can't vouch for it but it has some good points not mentioned before. I'm posting it to get it into the archives.
Steps:
1. Begin every project like this by cleaning the item just use dish soap and a soft cloth, no abrasives yet.
2. Before we begin sanding here is some helpful tips to ensure a proper finish:
Tips/Rules for Sanding: - (Optional) Sand face of entire surface, not just the scratched area this creates a smoother finish that is free from depressions.
- It is preferable to wet sand under a light stream of water which is better than simply wetting the surface and the sandpaper.
- When going up in grit number (finer grit) wash surface, preferably with dish soap to make sure the surface is free of lower grit particles.
- When switching from one grit to the other sand in a different direction (up and down, now left and right) this way you can easily gauge your progress in removing the lower grit's sand lines. To view these lines while wet simply hold surface at an angle to the light.
- Use room temperature to cold water temps for wet sanding.
- On flat surfaces it is easier to wrap the sandpaper around a smooth wooden or hard plastic block this gives you more leverage and can give a more uniform surface in the end on flat/square pieces.
- With plastics, BEWARE of the cutting power of sandpaper you will be amazed how easy it is to sand down plastics.
- Wet sanding will cut less efficiently than dry sanding but produces a better finish and is all but required on 600 grit or higher sanding work.
- If dry sanding remember to fully dry the surface to sand for the best results.
3. With Medium to deep scratches start with 400 grit paper, wet sandpaper and surface and begin sanding in whatever way feels comfortable. After only 15 seconds or so look at the scratch(es). If they are starting to soften or are even completely gone keep sanding until they are gone. If no progress was made at all go to step 3a.
3a. Major scratches or plastics/resins that are exceptionally hard will require more time/effort and so starting at a lower grit sandpaper will reduce that time/effort. Jump down to 220, scratch for a few seconds, check, scratch some more, check. When the scratches are gone IMMEDIATELY clean the surface and move up to 320 grit different direction until the 220 scratches are gone. Then move back to 400 wet and use until 320 scratches are gone.
4. Work your way up slowly from 400 to 600 to 800 to 1000 to 1500 to 2000 or even 3000 or higher if you choose (3000 produces an almost perfect finish by itself). Make sure to complete sanding the scratches left at a specific grit before going to a higher number!!!! Otherwise you'll have to go back down and re-sand all over.
5. Now that you have a smooth finish that has a very light matte look you are almost done make sure to wash THOROUGHLY before the next step and wipe dry with a very soft cloth and give it a couple of minutes to let it air dry.
6. Take out the rubbing/polishing cloth and Rubbing Compound. Squirt a bit on the surface and a bit on the cloth. Begin to vigorously rub the compound on the surface as if you are sanding rub until product completely disappears or dries out apply some more and rub some more until there is a PERFECTLY clear surface or Mirror shine, flawless finish on a colored plastic.
7. Lightly dampen the other end of the polishing cloth and wipe off excess rubbing compound from surface again dry with soft towel and let dry for several minutes.
8. (Optional) Apply a layer of Meguiar’s NXT wax to really shine things up let haze and polish off, then let wax coat harden by letting the surface dry for a couple of hours.
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_________________ Guy Buchanan
Deceased K-IV 1200
A glider pilot too. |
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