Chromate Coatings Better to Spray or Dip?

Hi Jared,

Chromates can be applied by spray or immersion, but in your case, immersion sounds more feasible than spray because it doesn't appear that you can contain the spray. And it also sounds like a person will be doing the spraying, so you will have to prevent the person from coming into contact with the spray, which won't be simple.

An immersion process can easily provide a uniform conversion coating. I would suggest to rinse the treated boxes with fresh water after removing them from the chromating stage.

It sounds as if your spray method using a spray gun is a manual operation in which case dipping is infinitely better. A good even coating can be got by making sure the aluminium is clean all over and with slight agitation to get the chromate into all parts of the box. Make sure that rinsing is done well and that it is dried correctly.

Hundreds (maybe thousands) of shops chromate aluminum by dipping. It's the way to go. The aluminum also must be pretreated (usually alkaline cleaned, etched, and desmutted), and it's very straightforward to do this in a dip line.

You can either dip or spray. Your chromate chemical supplier can help you decide which best fits your needs, however, there is so little spraying done that very few vendors really know how to spray chromate. Also, by dipping you can control the liquid effluent much easier. Some local EPA people will get all over you for spraying chromate, hence the exhaust and fume scrubbing facility will be very expensive.

SO DIP!