Spot Weld Marks
On certain sheet metal parts made of 16-gauge cold rolled steel, we have trouble with spot weld marks showing through the paint finish. How do we eliminate this problem?
Q. I’m the plating and paint shop foreman of a company that makes office machines. In order to get a first-rate finish, we use a five-stage washer to apply an iron phosphate. After dry-off, we apply an epoxy primer and then a polyurethane topcoat to all painted parts with an electrostatic spray gun. Total dry film thickness is 3 mils. On certain sheet metal parts made of 16-gauge cold rolled steel, we have trouble with spot weld marks showing through the paint finish. How do we eliminate this problem? B.F.
A. It is often difficult to hide surface defects with a paint film, even at a 3-mil dry film thickness. Paints, as well as powder coatings, tend to conform to the surface on which they are applied. Paints over spot weld marks, which come in two forms—holes and ridges—will follow the rules of surface coatings. These surface defects can only be eliminated by cosmetic repair, requiring hand work. I suggest you fill the holes using a body putty or filling compound and then sanding them smooth. If the weld marks are ridges, they can be removed by hand-grinding using a power tool.
Related Content
-
Finishing Systems Provider Celebrates 150 Years, Looks to Future
From humble beginnings as an Indiana-based tin shop, Koch Finishing Systems has evolved into one of the most trusted finishing equipment providers in the industry.
-
Masking Solutions Provider CFS Dramatically Expands Capabilities and Capacity
Custom Fabrication & Supplies (CFS) completed a new plant expansion packing 10 times the capacity into twice the space. It dramatically enhances the supplier’s custom capabilities to provide extremely precise and cost-effective masking solutions.
-
Products Finishing Reveals 2024 Qualifying Top Shops
PF reveals the qualifying shops in its annual Top Shops Benchmarking Survey — a program designed to offer shops insights into their overall performance in the industry.