Restoring air intake grille

[cheepskatebob]

I am struggling to find a solution to the restoration of the air intake grille. As these were cast in Mazak (monkey metal) the chrome is pitted in the usual places. I have tried two reputable chrome platers and neither will take it on due to the base metal, size and complexity.

Grasping at straws a bit I decided to try out Rustoleum's chrome spray paint and have practiced on one end of a spare grille but the finish is more like aluminium spray paint and isn't reflective enough to pass for real chrome. I found that the corrosion bumps on the chrome and especially the nickel plating are very hard to flatten and ended up having to use a file as well as coarse wet and dry papers of differnt grades. I did enough preparation to the practice piece to establish that I would be able to achieve a reasonable finish with high build 2k primer and body filler to fill the pits before spraying with the Rustoleum and a finishing clear coat.

Attachment Deleted

I asked my local powder coating firm, who did a great job on engine parts for me a few years ago.  They have a reasonably shiny Chrome effect finish but pointed out that the powder coating won't fill in the pits and you can't use a plastic filler before powder coating due to he need to earth the part for the electrostatic powder to stick to it.

I have also been in touch with a couple of companies who do a more convincing, but very expensive, chrome effect paint process but they are not interested in taking on such an intricate part.

A better second-hand part might be an option of course but I'm guessing
that it will be difficult to find a decent one as they will all be about
50 years old and suffering from the same DMMS (disintegrating monkey
metal syndrome).

I am running out of ideas for this one.

Has anyone on the forum looked into this problem and found a better solution?

[jimbo]

Just a thought, as the intake mesh has been removed and seeing how you mentioned high build filler  - which would need rubbind down ... If there are pits, can you get 1 copper plate session , then run solder into the worst divots and dremel that smooth knowing that if the copper goes then you've buffed too much off, and then have it coppoer plated again as a new base for the chrome?

[djm16]

Were it not so complex a casting, the recommended way of restoring pitted chromed mazak is to drill each and every corrosion spot, plate heavily with copper, flat back, repeat until all the pits are filled with copper. Then nickel / chrome plate. However, I have just watched a Youtube video about Super Alloy 1 Pot Metal Solder. Not yet tried it myself though.

Given the complexity of the casting an alternative is to rub it all back, remove corrosion pits and then silver plate and clear coat the final finish. Note I have never done this, the chemicals are expensive, and they have a relatively short shelf life.

[Sam Bee]

Many more of these grills are inevitably going to suffer the same fate. Long term answer is have them available in an alternative more durable metal. With 3-D scanning and then producing multiple 3D printed moulding cores for casting, a technique now in common use, it should be possible. It is a process similar to 'lost wax' casting, but the cores are churned out at the press of a button. Cost - heaven only knows!

[cheepskatebob]

Thanks for the suggestions. Since posting this last week I have made an undexpected breakthrough in finding someone who has all the Chrome Spray kit only 3 miles away from my home! He is relatively new to this process and isn't advertising yet but claims to be one of only four companies in the UK who have invested the £10k in the kit.
I have had the grille sand and bead blasted which has removed most of the old chrome plating and has left a surface free of corrosion bumps. The corrosion pits are clean and will be filled with body filler and primed 2K high-build primer.
What a tedious job it is! I am using a tiny spatula (nicked from my wife's art studio) to apply the filler and have had to cut thin plywood strips with various grades of wet and dry sandpaper glued to them to get into the fins of grille. However I am now on a mission to get it in the best shape possible for the final chrome spray finish. I will update soon.

[johnwp5bcoupe]

David Green went down this path from memory the result wasn't that good!

[percy]

There's a couple on Ebay right now. They do respond well to a good scrubbing with hot water & fairy liquid followed by a polish with autosol.