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Problem rinsing silicated cleaners

The advise is always to use a silicated cleaner you must rinse well due to the gelatinous film formed with the acids.

I don't have an ultrasonic cleaner, so it would help to use fluorides in acid dips to remove silicates?

Daniel Hernandez
Plating shop - Bucaramanga Santander Colombia
December 5, 2010

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December 10, 2010

Daniel,

Are you talking about silicated soak cleaners, such as those produced by the likes of Chemetall, Atotech and MacDermid?

If you are then a good rinse for 2-3 minutes in cold, running, agitated water should suffice. If there is a contamination on the surface after rinsing a dilute acid rinse with either nitric acid or sulfuric acid should suffice to neutralise.

I would avoid using HF if I was you, that is a nasty acid to play with and I really don't think it'll do you any favours to be quite honest.

Brian Terry
Aerospace - Yeovil, Somerset, UK

Silicated cleaners are a serious pain if you do not get them into a rinse tank quite rapidly after coming out of the tank. The hotter the tank is, the faster you need to move it. I have seen dried on cleaner where we had to grit blast the surface.

James Watts
- Navarre, Florida
December 10, 2010

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Silicates are insoluble in neutral and acids. If the first rinse after using a silicated cleaner is neutral or acid, silicates precipitate as an insoluble film that is very difficult to remove. I suggest that the first rinse after alkaline silicated cleaners be at at pH 8 or higher. The silicates can then easily removed. Then transfer to a clean rinse and proceed from therein to acid treatments required for the metal substrate.

Don Baudrand
Consultant - Poulsbo, Washington
(Don is co-author of "Plating on Plastics" [on Amazon or AbeBooks affil links]
           and "Plating ABS Plastics" [on Amazon or eBay or AbeBooks affil links])
December 29, 2010