Painting Methods

Q. I run the paint shop at a plant that makes enclosures for industrial controls. My problem is cleaning and corrosion protection for the products we manufacture. We produce about 1000 units per year, made of mild steel, 6 ft long, 3 ft wide and 4 inches deep. They must be dry to the touch for assembly into airtight enclosures. Although they are used indoors, they are stored outdoors for one to six months. Currently, we are spray cleaning and spray painting. The box section of the structure makes corrosion protection by spray painting questionable. F. P.

A. Although you didn’t ask a question, I think I understand the problem. You need a method for applying some kind of paint to protect your parts for one to six months outdoors and for the rest of their service life indoors. Following is a list of several available options with comments about their viability: 

1. Electrocoating: This method will apply paint evenly on all surfaces, but if your production rate is too low it will be difficult to justify the large expenditure for capital equipment.
2. Flow coating: With the exception of a continuous coater, this method may not apply paint on all the surfaces of your products, unless you turn them and run more than one pass.
3. Dip coating: This method will apply paint on all the surfaces, but may not have a good appearance because of runs, shadows and the wedge effect normally associated with dip coating.
4. Spray painting: This method will not apply paint evenly on all surfaces no matter how much care is taken to insure complete coverage and to eliminate overspray.
   To get complete cleaning and painting of all surfaces, I think the dip cleaning and coating methods are the most viable for your products.