Polishing old plastic lenses from nav lights

[DoubleEnder]

I have some nice old side lights, chromed brass, heavy tear drop shaped from I would say the 1960s? Maybe off a Chris Craft or something but they look good and I like them. However the moulded (plastic?Perspex,? Acrylic?) lenses are crazed and dull. They are curved, and bulge slightly and have 3 ridges top and bottom. No chance of finding new replacements. I'll try to add a picture later, but anyone got any ideas on a refurb technique? Could a polishing wheel do the job, if so what kind of cutting/polishing paste.....?

Thank you
Graham

 

[Concerto]

I would use a cutting compound on a Dremmel (or similar) to shine the plastic as much as possible, then use a polish to seal dirt out. If you use too large a polishing wheel (eg in a drill) you will be likely to round the sharp edges of the Fresnel lens.

 

[Lon nan Gruagach]

Or.. make a mould and pour clear acrylic... craft shopd sell the kit for making your own wild flower paperweights.
Just I dont know what the mould should be made of.....

 

[VicS]

Or.. make a mould and pour clear acrylic... craft shopd sell the kit for making your own wild flower paperweights.
Just I dont know what the mould should be made of.....

The mould will probably be silicone rubber ...

But the problem maybe making the new lenses the correct colours unless of course they are colourless and fitted over coloured LEDs

 

[salar]

The Plastic People recommend Brasso for polishing once you have got the scratches out with progressively finer wet and dry.

 

[Robin]

I have some nice old side lights, chromed brass, heavy tear drop shaped from I would say the 1960s? Maybe off a Chris Craft or something but they look good and I like them. However the moulded (plastic?Perspex,? Acrylic?) lenses are crazed and dull. They are curved, and bulge slightly and have 3 ridges top and bottom. No chance of finding new replacements. I'll try to add a picture later, but anyone got any ideas on a refurb technique? Could a polishing wheel do the job, if so what kind of cutting/polishing paste.....?

Thank you
Graham

Here in the USA the auto stores sell headlight lens restorer polish kits that might work, does Halfords et al have anything maybe?

 

[colind3782]

Cheap toothpaste works well before you spring for the dearer alternatives.

 

[Rhyddid]

Could this help your predicament?
https://youtu.be/b8KzRFo1K8Y

 

[Robin]

Could this help your predicament?
https://youtu.be/b8KzRFo1K8Y

she has nice looking headlights:encouragement:

 

[Marine Reflections]

I have some nice old side lights, chromed brass, heavy tear drop shaped from I would say the 1960s? Maybe off a Chris Craft or something but they look good and I like them. However the moulded (plastic?Perspex,? Acrylic?) lenses are crazed and dull. They are curved, and bulge slightly and have 3 ridges top and bottom. No chance of finding new replacements. I'll try to add a picture later, but anyone got any ideas on a refurb technique? Could a polishing wheel do the job, if so what kind of cutting/polishing paste.....?

Thank you
Graham

If the lens is just dull then most of the above will work, but if it is crazed as you say then I'm afraid usually the crazing is all the way through and polishing won't remove this.

I would go down the route Salar recommended - fine paper (2500 /3000) then polish up on your wheel if it was slow enough with some compound, although I guess your challenge there would be the ridges. Perhaps replace the paper with a course compound as others say.
Be careful with dremel type polishing kits as these are far too small and will more than likely burn the lens. Best would be slow rotation on a wide wheel on its edge.

 

[lw395]

I'd do it by hand.
You may not need w&d, try a relatively coarse polish like Solvol Autosol (or any aluminium polish for hand use), then a finer one like T cut.
The different grades of Farecla are good for this too.
An old toothbrush is a useful tool for the Solvol.

 

[DoubleEnder]

Thanks everyone lets see how it goes

 

[Binman]

+1 for toothpaste, buy one that's a bit gritty, say stay white or smokers toothpaste, have tried this tip on very cloudy car head lamps, works well, won't harm, put plenty on a work it hard with your fingers first then a toothbrush with plenty more paste on.

 

[Jamesuk]

Try using Peak Polish

 

[geoffatstanpit]

I made Perspex lenses for underwater photography by a 3-stage process - Machine the shape on a lathe, grind out the machining lines with 400grade wet-and-dry, and finally T-cut on a J-cloth.

 

[RAI]

I tried various polishes but the crazing was inside the plastic. I then discovered that despite their 35 years of age, the lamps did have replacement lenses available from the original manufacturer. So new lenses all round. Maybe Google harder.

 

[rogerthebodger]

Polishing entails removing material and will only be effective on surface scratcher / defects. Crazing of plastics tend to be deeper and thus cannot be polished out.

I have done a lot of polishing, mainly stainless steel but some plastics also and, I have some crazed perspex hatches but wiuld not entertain trying to polish out the crazing.

 

[Modulation]

+1. I've used Brasso in similar circumstances. Be aware that it will take a lot of rubbing to get rid that cloudiness. Fast it ain't
'

 

[skenn_ie]

If anyone is still interested in this thread, I suggest a polishing mop as used by silversmiths. You can get them for a Dremmel too. They consist of a stack of cotton fabric disks sandwiched together. Silversmiths use Rouge as the polishing compound, but you can get graded perspex polish.