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Masking Chromic Anodise

We chromic anodise an aluminium alloy cast component to MIL-A-8625 Type I Class 1. There are certain areas on this components that need to be electrical conductive, therefore we strip the anodise (using glass bead blast) and chemical film to MIL-C-5541 Class 3. This is a very long and expensive process, ideally we would like to be able to mask the areas during the initial anodising process, which would therefore remove the need for blasting.

I have been unable to find a suitable masking solution, none of the brush applied solutions are compatible with chromic anodising, are there any tapes that are suitable for chromic anodising? The masked areas do not need to very clean cut - we can live with a bit of leaking under the mask.

Some of the areas to be masked are flat surfaces and some are diameters. There are some areas that we could use a tight rubber mould to mask, but other areas would be unsuitable and more suited to tape or brush applied material.

Thank you for any help that you can supply.

Chris Amey
Consumer - Fareham, Hampshire, UK
2007

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The product I use works very well for type 2, and type 3 anodizing, also claims to be good for chromic acid anodizing. Its a brush-on product. Its called Microshield, manufactured by Tobler. I'm not sure if its available in the UK, though.

Marc Green
anodizer - Boise, Idaho
2007

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