Just as bad 
Peter wrote:
What you have to be very careful with is not creating flat surfaces, or generally surfaces whose curvature differs from the surroundings. You get weird optical effects then.
Yes, that is indeed a big issue. Thankfully the affected windows are pretty straight.
What you have to be very careful with is not creating flat surfaces, or generally surfaces whose curvature differs from the surroundings. You get weird optical effects then.
Thanks guys.
the “milky” one is one side window only. So that one will need replacement at some stage.
The windscreen on the pax side suffered some bruising from an old cover. That would be the one which might be repairable with some of those methods.
Some good advice here, thanks.
It is possible to polish polycarbonate, search the web for restoration of polycarbonate headlights. I am about to do this on my car and will report the results.
Based on experience with polycarbonate you’ll get results that are plenty OK for headlights but not good enough for a windscreen. Acrylic is much harder (also more brittle and not as strong) so aircraft windscreens are much easier in this regard, notwithstanding the potential problems with distortion.
Meguiars link and similar companies make good polish once you get the surface flat and uniform with wet sanding down to 2000 grit or so. I once did a badly scratched motorcycle windshield starting with a file but don’t use anything coarser than necessary because each step finer is lot of work. You can then use several grades of polish working toward the final polished finish after sanding. It’s important not to put deep scratches in the surface in the initial steps, uniformity at every stage minimizes the work at the next finer stage.
As already mentioned.“milky” forget it and get.a new windscreen.
Scratches in perspex I have seen three methods used successfully.
1) aluminium foil ( but only seen it use on the plastic headlights etc). I don’t know if I would use it on my aircraft windscreen unless I tested it first.
2) Brasso if that’s the one that comes with the wool. Gentle movements no scrubbing letting the wool do the work.
3) Toothpaste on a soft damp cloth.
Whilst writing this a friend has just mentioned a 4th.
4) Ash from a wood fire. Filtered so it is just the fine ash again applied gently on a soft damp cloth. Avoid circling motions as you run the risk of the windscreen blooming when flying into direct sunlight
My recommendation would be to test a small area before going at the area in front of your face.
We once had a Citation windscreen polished.
That decision subsequently cost us around $40,000 when the windshield had to be replaced due to the distortion caused by the polishing.
Stickandrudderman wrote:
Surprisingly good results can be had by flashing the surface with a blow torch!
Please don’t do that. Flame polishing introduces internal stresses in the acrylic, which may lead to cracking – in particular, it will most likely crack if you later wipe the window with alcohol (for example, to remove ice).
Silvaire wrote:
If the transparency were made of polycarbonate (Lexan) it cannot be polished and will be ruined if you were to try.
It is possible to polish polycarbonate, search the web for restoration of polycarbonate headlights. I am about to do this on my car and will report the results.
https://gcabrasives.co.uk/product/micro-mesh-kr70-acrylic-plastic-restoration-kit/
This is the one I’ve used, but to do a large area like a whole window may take a full day.
I did a Robin canopy with localised deep scratches, some very light (dirty cloth) type scratches over quite a bit of it, and a bit of overspray from someone.
That took a whole weekend.
Blowtorch handled by a very skilled and experienced operator?
I shared with an artist guy who had no fear when tackling perspex.
