What is "Paint Grip Steel"?
By Sock Woodruff
A common class of pretreatments used to obtain good bonding qualities between paint and galvanized coatings are phosphate pretreatments. Zinc phosphate is used as a pretreatment on coil prepainting lines and in post fabrication factory paint processes. It can also be applied directly on galvanizing lines to provide a  product designed for field painting.

Bonderized steel is produced by various domestic and foreign sources. There is no standard for the gray finish with regard to smoothness, texture or shade of color.

RainTrade Corporation/Guttersupply.com will not be responsible for surface or color variations resulting from material sources and/or phosphate coating methods.

Bonderized steel is galvanized steel that is processed through a phosphate bath. This provides a corrosion inhibiting, crystalline zinc phosphate, micro-porous surface that promotes adhesion of top coatings. This produces the dull gray color characteristic of Bonderized that provides as an excellent "primer" for painting applications. Phosphate acts as an insulator between the drying action of the galvanized coating and the paint, promoting longer paint adhesion. That is why it has been called "Paintgrip" by the trade. Bonderized material should be immediately painted after installation, as the exposed phosphate coating is prone to white rust.

Painting Suggestions
RainTrade Corporation/Guttersupply.com is not in the Paint business. There are general practices used in the trade and we offer these suggested practices without assuming responsibility for any consequences. Product surfaces can be contaminated with dirt and oils during the manufacturing process, warehousing, shipping, job site handling and installation. Humidity and temperature can effect bonding and drying time of coatings. We recommend contacting a reliable professional painter or an industrial paint supplier for specific information regarding your application and requirements.

Some Alkyd and Alkyd Polyurethane coatings require expensive additives to assure proper bonding with galvanized based coated steel. Latex paints have more ability to expand and contract with metal temperature changes. We recommend a primer coat be applied regardless of the preconditioned bonderized surface or the coating type selected.

Materials should be prepared by removing any chemical residue with a solution of distilled vinegar or galvanize wash, available in hardware stores. Oil contamination may require an alkaline cleaner. Material must be thoroughly dried and immediately coated after cleaning. Then use an antirust primer and finish them with a good exterior grade paint recommended for metal.

As with all applications involving post painting, RainTrade Corporation/Guttersupply.com recommends testing the compatibility of particular field paints on samples of phosphate pretreated galvanized steel prior to coating the final product.

Sock Woodruff is founder and partner of GutterSupply.com, the leading manufacturer and distributor of gutter supplies, copper rain chains, and related tools and equipment.