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by Ron Joseph

April, 2005

CARC Coatings MIL-DTL-64159 Type II Waterborne

Q. Specification alodine MIL C 5541 class C, Primer Mil P23377 type 1 class 2, finish MIL-DTL-64159 TYPE II WATERBORNE. We have a problem where a heavier coating is applied a bubbling of the surface is occuring after approx 1 hour. Primer is cured for 1 hour at 60 degrees centigrade prior to application of Finish coat. components are quiet complex does this paint lend itself to electrostatic application for a more consistant film thickness. Look forward to your reply. Regards

A. It sounds as if you are running into a problem with water entrapment in the film. Try getting more air to the surface of the painted parts so that you can evaporate the water quickly. Also measure the paint dry film thickness to ensure that you are not applying too thick a coating film.

The coating can be applied electrostatically, but you must be able to properly isolate the pressure pot or spray gun from the ground. If you can't do this then you will short out the system and get no benefit from the electrostatics.

If you still have problems please get back to me.

Best wishes,

Ron Joseph

Q2. Thank you for your reply. So you do not think it is the Primer that is causing the problem, is this the primer the US Military are still using with MIL-DTL-64159 Type II.

A2. Apply the coating to a piece of chromate conversion coated aluminum without the primer and see if the bubbling still occurs.

Ensure that all of the water from the MIL-C-5541 process has completely evaporated.

Ensure that the MIL-P-23377 primer is completely dry before you apply the topcoat.

Please get back to me if you still have problems.

Best wishes,

Ron Joseph

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