Q. I’m looking for an environmentally friendly pretreat for reinforcing rods that are to be epoxy coated on a conveyor line. What is available in the market that can increase my cathodic E-coat performance? W.B.
A. Assuming the rods are mild steel, you probably have the most options available to you. A traditional iron phosphate pretreatment can be a relatively benign process. The first stage cleaner can be recycled by use of skimmers and separators. The iron phosphate stage can be run to minimize or eliminate sludging while the final non-chrome seal may never need dumping. See the online Supplier section of pfonline.com. Another option could be the relatively new NT-1 pretreatment available through Henkel. This is a multi-metal pretreatment that contains no regulated heavy metals.