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Hologram Finish on Iron Name Plate

I have a 0.3mm iron name plate. The surface was polished to high gloss. When you looked at different angle, you could see a shining hologram (a rainbow like appearance). What chemical or process could make this effect?

Lorin Tam
plastics - Hong Kong
2001

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G'day Lorin.

I think what you are looking at is not a hologram but residual grease left over from the polishing compound. It's like seeing petrol/oil spilt on a wet road.The different colours are produced by the varying thickness of the oil/grease, diffracted by the light.

Richard Bancroft
- Parkdale, Victoria, Australia
2001

Hi Richard,

Thanks for your reply. I am afraid that this was not the case. My client claimed that it was the Rainbow Hologram finish. He wanted me to produce this effect on his logo name plate.

I have checked out some of the websites about hologram. This effect could be made by Silver-Halide process and embossing. Unfortunately, these methods only apply to film substrate. It seems that it won't work on hard surface such as the iron name plate. Could anyone help?

Lorin Tam
- Hong Kong
2001

Dear Lorin,

My first guess is that hologram you are looking at might not have been intentionally applied. It seems more like someone had sprayed a coating over the nameplate and didn't do a good job with mixing the lacquer and thinner. If you mix too much thinner in with a lacquer, you will get a "rainbow" which looks not quite like a hologram, but more like the oily refraction Mr. Bancroft spoke of. Only other guesses would be a graphic immersion, but to my knowledge (which isn't much) those are usually opaque.

Hope that can help.

Jake Koch
G. J. Nikolas &Co.,Inc.

Bellwood, Illinois

2001