It's actually for car headlights that are no longer available. To replace the internal reflector assemblies with modern ones, as the originals are plated plastic which fails. But the glass outer cover has a fresnel lens built in which the modern reflectors don't need. So would it be economically possible to have copies made of the toughened glass outer but in plain glass? Or perhaps some other material?
Replating the plastic sounds the most viable option. Bring it up on a classic car forum - it must be a well-solved problem.
It's not - at least for manageable production runs. They're often of the order of 10,000 minimum.
I asked here because it's not easily solved and I'm looking for a viable work round at a reasonable cost - and there are many here with various skills and experience - probably more so than on a classic car group, of which I read several.
could you plate it with silver, using the Tollens(?) Reaction? IIRC it's something like silver nitrate solution and an aldehyde, the silver is precipitatedout on whatever surface the liquid is in contact with; amateur telescope makers use it to silver their mirrors (for infra-red mainly, and when a vapour-deposition chamber isn't available to 'em), and if you could then coat it with a clear varnish/resin it'd stop the silver tarnishing.
Dave H. (The engineer formerly known as Homeless)
Am I right in saying you've got one light assembly thats lost silvering, and need it fixed? For lights other than headlights the simplest fix is paint the silvering white, but thats no good for headlights. Glass can be silver plated glass using electrolysis. Before people frown, yes it doesnt work like conventional electroplating, but it does work. Put distilled water in the headlight plastic assy, put silver electrodes in and pass 9v 1mA between them. Along the way silver will fall out and plate the container. 1mA gets a small patch of plate after many hours, so you'll presumably want more current.
There is also self adhesive mirror on a roll, if pushed you could chop it and apply like a mosaic. Plating much better though! Hopefully coating the plating thickly with clear varnish will help it stay in place longer. Adding say 1% of fibre to the varnish should increase lifetime further without having too much impact on optical clarity.
Redesigning the headlight optics doesnt sound an appealing prospect to me, and it would look very out of chracter.
NT
Am I right in saying you've got one light assembly thats lost silvering, and need it fixed? For lights other than headlights the simplest fix is paint the silvering white, but thats no good for headlights. Glass can be silver plated glass using electrolysis. Before people frown, yes it doesnt work like conventional electroplating, but it does work. Put distilled water in the headlight plastic assy, put silver electrodes in and pass 9v 1mA between them. Along the way silver will fall out and plate the container. 1mA gets a small patch of plate after many hours, so you'll presumably want more current.
There is also self adhesive mirror on a roll, if pushed you could chop it and apply like a mosaic. Plating much better though! Hopefully coating the plating thickly with clear varnish will help it stay in place longer. Adding say 1% of fibre to the varnish should increase lifetime further without having too much impact on optical clarity.
Redesigning the headlight optics doesnt sound an appealing prospect to me, and it would look very out of chracter.
Almost forgot, another option would be paint the plastic with aquadag or similar, and electroplate conventionally.
Some of these I've tried, some not.
NT
They're not cast, they're pressed. If you can achieve suitable surface quality and accuracy with slumped glass (gravity presses it under its own weight) then many hot-glass craft workers should be able to do one-offs for you. Making the moulds isn't especially hard either. Try asking in rec,crafts.glass.
Thanks Andy - I'll give that a try.
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