Refurbing Lewmar window ‘glass’

[stranded]

Several of the panes in our 17 year old (rose tinted if relevant) Lewmar hatches and port lights have a few scratches I would like to improve if possible. I have read that polishing them with a fine compound can help, but before I try that, does anyone know if the tinting is within the plastic or just a film? And I suppose, does polishing work?

 

[Sandy]

I am told that toothpaste is good for removing scratches. Why not give that a try on a small section before doing anything drastic.

 

[mrangry]

These will be acrylic and as long as just surface scratches and not crazing then can be sanded and polished out.
How To Remove Scratches From Acrylic.

 

[stranded]

Thanks chaps - I’ll pick an inconspicuous one to try - could be a perfect job for my nifty new Flex cordless mini sander/polisher.

 

[pmagowan]

I sanded and polished my crazed and scratched hatches to good effect. Is a tricky job though as does not sand easily and prone to melting a bit if over sanded. Need to take it easy but I used a relatively thick grit to get the surface off as took forever with anything else. Then I cycled down through the grit sizes to wet and dry. Then I used a polishing angle grinder job that works on GRP with a cut and polish. Looked almost as good as new apart from the hard to get bits at the join with the frame which, due to needing careful hand sanding, got less vigorous treatment.

 

[thinwater]

I am told that toothpaste is good for removing scratches. Why not give that a try on a small section before doing anything drastic.

If your toothpaste has enough abrasive to remove scratches, think of what it is doing to your enamel.

Some do. Don't use those brands on your teeth! People have been known to scrub of their enamel in the quest for white teeth. Then it is pull-them-all.

 

[pmagowan]

Unless your toothpaste is 80 grit it ain’t doing much for the hatch and if it is you don’t have any teeth now anyway

 

[The Q]

You can buy kits for removing the surface crazing / fogging of plastic / acrylic car head lights.
They seem to be very effective..

 

[RunAgroundHard]

I sanded and polished my crazed and scratched hatches to good effect. Is a tricky job though …

It’s good to read this experience. I have similar hatches to your images, with crazed glass.

Many other threads on this subject state it can’t be done, that the cracks are throughout the thickness, need to replace the glass, use toothpaste.

Your thread shows that it can be done with care. Can you advise the grits?

 

[pmagowan]

I just went at it with sand paper. Can’t remember the exact grits but I remember the wet and dry that I initially used was taking so long that I changed to an aggressive grit to get the surface off. That heated up when held for too long in one spot and caused the dust to melt but it actually came off ok. Basically use what works to get the surface off then it is simply a matter of polishing the scratches out by going down through the grits and then using a polishing compound.

 

[mrangry]

If it is crazed due to UV damage no amount of sanding will fix it

 

[harvey38]

This is the product I use on glider canopies to remove scratches, just be careful not to build up heat.

Canopy Scratch Repair Kit

 

[RunAgroundHard]

If it is crazed due to UV damage no amount of sanding will fix it

Why is this the case?

 

[stranded]

If it is crazed due to UV damage no amount of sanding will fix it

And yet pmagowan seems to have managed it very well. In any case ours are not crazed, just some scratches, so I look forward to getting at them applying the extremely helpful knowledge, suggestions and experience on here.

 

[PaulRainbow]

And yet pmagowan seems to have managed it very well. In any case ours are not crazed, just some scratches, so I look forward to getting at them applying the extremely helpful knowledge, suggestions and experience on here.

If it's just scratches, a polishing compound will get rid of them. I'd try some Farecla G10. If you use a machine to do the job, do not dwell on one spot, do not let heat build up and do not let it get dry. Have a spray bottle of water to hand.

 

[mrangry]

Why is this the case?

Because scratches are on the surface and can therefore material can be removed by sanding to remove them. Crazing is not on the surface so sanding wont remove.

 

[pmagowan]

Because scratches are on the surface and can therefore material can be removed by sanding to remove them. Crazing is not on the surface so sanding wont remove.

Not true. UV damage is almost exclusively on the surface. It is rare for crazing to go even a millimeter deep. These plastics are essentially opaque to damaging UV light. My windows had 40 odd years of exposure with significant crazing and you can see the after and before pics above.

 

[sailorbenji]

Several of the panes in our 17 year old (rose tinted if relevant) Lewmar hatches and port lights have a few scratches I would like to improve if possible. I have read that polishing them with a fine compound can help, but before I try that, does anyone know if the tinting is within the plastic or just a film? And I suppose, does polishing work?

To answer the first part of your question (plenty of answer already to the second part), the tint is throughout the acrylic, it is not just a film on the top or bottom surfaces.

 

[LittleSister]

I remember reading - but unfortunately not the details - that certain common polishes (silicon?) will craze (I think) acrylic (as opposed to polycarbonate). That type of non-UV crazing is apparently deep and not just on the surface.

(The previous owner of my car (or the garage I bought it from) apparently made that mistake with its dash, which is crazed. Not a major issue, but it's aesthetically irksome, and slightly worsens the visibility of the already difficult to see in bright daylight instruments.)

 

[stranded]

To answer the first part of your question (plenty of answer already to the second part), the tint is throughout the acrylic, it is not just a film on the top or bottom surfaces.

Ah, thanks Benji - I rather forgot that myself in the welter of helpful advice.