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[Worf]

I am currently restoring a vehicle with a number of mazak (monkey metal) castings. Door handles, grilles etc. From (long) past experience they are virtually impossible to rechrome successfully as they corrode from the inside and leave craters in the surface. Technology may well have moved on however   Anyone with any experience of metal refinishing?

[GAHC]

Not exactly sure of the part you are considering but PVD coatings don't need immersion, they are done in vacuum. Its how metal is deposited onto plastic - there is an outfit in Cambridge called Tecvac who do it (mainly for autosport and aero) - may be worth a bit of googling...

Thanks

Giles

[Worf]

Interesting reading and probably the way forward seeing they are trying to ban traditional chroming in the UK (or was that an EU thing )

They probably wouldnt be interested in "one-offs" (ok 2) such as these.

Recasting in brass and then chrome plating would probably be very expensive 

[agg221]

PVD would be an option - there are a couple of other places that might do it for you such as Teer Coatings. It needs to be a very good surface before you start. An alternative is to overplate in something which uses a bath chemistry which is not corrosive to the Mazak and then chrome over the top. Ashford Chrome Plating could probably advise on options that might be suitable for that. Another related option would be to use coldspray, which does not work with metals that will give a suitable finish but would allow you to spray down a barrier layer which would act as a seal coat and could then be buffed up and overplated. I would be thinking of copper for that as it is commonly used under chrome anyway (e.g. swivels) and would give you a colour witness if you broke through while buffing. There is a place up near Manchester which offers hand-held coldspray which would probably be the best option for that route.

Alec

[GAHC]

most of the coatings companies will do one offs - generally they have a min order charge and then batch the work up with other similar stuff to help keep the unit cost down.

echo what Alec said after seeing the part, flashing the surface with a half way house coating may be a really good option - there are plenty of outfits around doing cold spray/plating/chem coatings. Give one of them a call and have a chat about what options they have - prices and routes to the right finish will probably vary by supplier

Giles

[agg221]

An even more radical suggestion which might keep costs down as you could do most of it yourself:

Paint with a high hardness epoxy primer such as POR-15.
Polish flat and smooth.
Electroless nickel with chrome overplating.

That would be equivalent to chrome plated taps etc. It won't last quite as long as the thicker metal finishes, but if done right it will be indistinguishable for decades.

Alec

[Worf]

Some very interesting suggestions. It would appear technology has moved on!
I did find one place that will conventionally chrome plate mazak, after filling all the craters with some sort of conductive solder. Sounds like a lot of labour and they could not guarantee it would be perfect.

The idea of coating in an epoxy primer appeals to me, followed by electroless nickel. Would this be sprayed or dipped by a specialist?
Alec, when you say chrome overplating this, would that be by PVD?

I will try calling a couple of specialists next week. From looking at other "classic" forums, (TR register for instance) it would appear that nobody is using this technology on classic car parts yet. A good niche in the market for some entrepreneur

Many thanks one and all.

[agg221]

The idea of coating in an epoxy primer appeals to me, followed by electroless nickel. Would this be sprayed or dipped by a specialist?
Alec, when you say chrome overplating this, would that be by PVD?

This would be straight electroplating over electroless nickel plating. When you see bright chrome plating on plastic, that's how it's done. This would probably be the cheapest route. Spraying will give a thicker layer but will need burnishing. PVD will typically be comparable to plating in thickness. If you can get a PVD coating on it, that would be the most durable but it would need to be metal on metal and would be more expensive. For that route, I would go coldspray to fill the craters and then burhish/polish to a satisfactory finish and then PVD chrome over the top. PVD is too high energy to onto plastic (or paint) satisfactorily under most conditions.

Alec

Alec

[Worf]

This would be straight electroplating over electroless nickel plating. When you see bright chrome plating on plastic, that's how it's done.
Alec

Alec

Ahh, I see. So the elecroless nickel would act a the conductor for conventional chrome plating onto plastic? I always thought that those  old fashioned chrome "cauldrons" got too hot for plastic (or POR15)

[agg221]

Ahh, I see. So the elecroless nickel would act a the conductor for conventional chrome plating onto plastic? I always thought that those  old fashioned chrome "cauldrons" got too hot for plastic (or POR15)

POR15 is an epoxy. Not sure exactly what temperature it will take but well over 150degC (some epoxies will take up to 250degC). Even hard chrome is only up to 65degC (decorative chrome is 35-40degC or so).

Alec