Paint Dry Film Thickness Standards

Q. Is there an industry standard for industrial equipment primer and paint Dry Film Thickness (DFT)? It seems like I have seen 3–5 mil thickness for both primer and paint for a total DFT of 6–10 mils. Any help would be appreciated. R.B.

 

A. There is no industry standard for industrial paint DFT. On the other hand, most manufacturers have their own set of standards. These standards are driven by such factors as chemical and physical exposure conditions, value and finishing costs for their products.

In my opinion, a DFT of 6–10 mils of paint on most industrial equipment is far too much. As I told R.A. in a previous Painting Clinic, “...at Westinghouse Research Labs., we specified a dry film thickness of 1 mil for each coat of paint on all test panels. These film thickness values were the same as those specified for painting our products. I recommend you do the same unless your customer specifies otherwise.” Over the past several decades, industrial painting has changed, owing to the use of new, more durable finishes.

For example, indoor industrial switchgear initially painted using two coats of air dry finishes was later painted using a baked one-coat enamel at 1 mil DFT. Outdoor switchgear initially painted using three coats of paint were later painted using two coats at a total of 2 mils DFT.

That said, there are exceptions. Certain products exposed to immersion, splash zone and ship-board conditions are often coated with dry film thicknesses greater than 1 mil per coat. But in my opinion 6–10 mils is too much paint. This contributes to higher manufacturing costs but not necessarily product improvement.