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Bacterial Problem in Electro Deposition Painting System

December 6, 2010

Dears,

We are facing very severe problem at our Electro Deposition painting line. The problem is that paint is becoming gel and settling down on bottom and on very next water tanks after ED it is on bottom and also floating on top. White contamination is also on top of tanks. We consult our paint supplier which is in Japan, they suggested that it is bacterial growth in bath and they have some Additives to kill these bacteria.
The problem is that it will take almost 3 months to import this additive.

Can anybody tell me the temporary solution of this problem?

Muhammad Ali
Painting Shop Employee - Lahore, Pakistan

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December 30, 2010

You should not have such a severe problem with bacteria. You should observe it when it starts.

You must check for bacteria every months. It is very easy. You dip special sticks in the solution and watch whether bacteria develop within 2 days.

The additive is highly important BUT it does not stand alone. The additive kills the bacteria in the solution, the ones that you cannot observe with naked eye. The slimy white particles you see, are bacteria protected by an armor. The additive is not able to break this armor.

You must transfer the solution via filtration to a reserve tank. Than you have to scrub the walls of the tank. afterwards fill the tank with clean DI water plus 1% sodium hypochlorite or formaldehyde or hydrogen peroxide. Let it stay there for 10 hours. Than clean the tank very well as residues of chlorine can harm the paint solution.

All the pipes, anode boxes etc must be clean and leached in the 1% solution.

Only than you can transfer the paint solution back to the tank and add the additive.

Sara Michaeli
Tel-Aviv-Yafo, Israel