Metal finishing Q&As since 1989

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Dip-Painting vs. Powder Coated Methods

August 29, 2008

My company owns several distribution centers and manufacturing plants across the US. We therefore house a lot of pallet racking systems. Our current specs for pallet racking requires that companies use a dip-painting method for structural steel. I am interested in finding out more about the powder-coated method. I've heard that it is more environmentally friendly and all-around superior to the traditional dip-painting method.

I would like to know the procedures for both methods from steel preparation to finish. I also would like some educated opinions on which one is a better fit for an industrial warehouse environment. I just don't know enough about it to make this decision!

Thanks!

Emma Hawkins
Project Engineer - Louisville, Ky, US

Many of our clients supply pallet racking for the store rooms of the shops in the high street, also for industrial situations. In the UK and Europe I can't think of anyone NOT using powder. Pretreatment depends upon the final site - outdoors or inside location. Outdoors will require using zinc phosphate followed by a polyester powder. Interior, you could get away with just a clean followed by a epoxy polyester powder, (you could pretreat using iron phosphate).

Terry Hickling
Birmingham, United Kingdom
September 8, 2008

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Your request for an answer to the question of dip painting leaves me wondering if your describing the "old" tank type of dip method whereas you simply run the substrate "parts" into a tank of solvent based paint via a conveyor or if your describing an E-coat system. E-coat systems work similar to these old systems however there is a huge difference on how the paint is applied. In an E-coat system, the paint or water-based coating is electrostatically charged thus called "e-coating". By adjusting the current flow of the water based E-coat paint, you can control precisely the mil thickness of the paint coating being applied. This can be a great cost savings in some situations. A drawback is that there is relatively few colors to choose from. E-coat itself has very good performance properties. If you happen to be referring to the old dip tank method....well, we just hope you aren't talking about that method.

Bob Utech
Benson, Minnesota
September 30, 2008

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Being in the drivers seat on this, you want things to work in your favor. All you have to do is decide how the coating on the racks is to perform and then tell it to your manufacturers. Rather than learning the powdercoating process, tell the supplier what you need, (eg.. excellent abrasive resistance and UV protection). Leave it up to him to give you what you ask for, agree on the cost and make sure you get a guarantee. When you tell him that you want dip painting, that gives him an out if the product fails ("The paint is failing but I gave you what you asked for").
Don't take my comment wrong, it's a very good idea to learn how each of these coatings work and what they are used for.

Sheldon Taylor
supply chain electronics
Wake Forest, North Carolina
October 7, 2008