Vapor Deposited Aluminum

[jaudette3]

I mentioned in a post today that I restored some Cibié Bi-Iode headlights using the vapor deposited aluminum process on the reflectors. I don't think that I have ever discussed that process here and I thought I would take moment for those who aren't familiar with it.

https://cdn.shopify.com/s/files/1/0284/3754/5020/files/170-1_540x.jpg?v=1616339692

Originally auto headlamp reflectors were plated with silver. Which makes sense as it is one of the most reflective metals. But it does have drawbacks – it’s expensive and it tarnishes over time. As a result, the modern process used by all automobile manufacturers is vapor deposited aluminum plating. A very thin layer of aluminum is deposited on the substrate and then protected by a coating of silica.

I’m sometimes asked why I go to all the trouble to have the reflectors restored with vapor deposited aluminum as opposed to simply chroming them. Chroming is a lot simpler as the process can be done a single plater as opposed to aluminum which requires having the reflectors prepared by one plater – copper -> nickel -> polishing – then sent to a second plater for the vapor deposited aluminum process. Also, it’s cheap to just chrome plate. The aluminum process is much more expensive and with more moving parts it takes longer..

So why aluminum? Chrome just doesn’t work very well. Using silver as the standard for reflectivity, vapor deposited aluminum is 95.6% as reflective as silver, while chrome is 63.5% as reflective as silver. You lose almost 1/3 of the light with chrome as opposed to aluminum. Here are the numbers:



Reflectance Comparison
Silver: .95512 = 100%
Aluminum: .91320 = 95.6%
Chrome: .60604 = 63.5%

Vapor deposited aluminum is the process used by all modern automotive manufacturers and is the best way to go for a restorer at this time.

Cheers,
John

[Joe Bob]

Plus chromers have mostly been shut down in the US. Ever try to get an old Chevy or 914 bumper re-done?