Evaluating Which Grit Options Work Best
People often start with a 36-80-grit coarse abrasive to get welds level, smooth out any deep scratches, and eliminate weld spatter. If the material has a high weld or weld spatter, 36-grit abrasive will remove the material efficiently.
However, a 60- or 80-grit abrasive is less aggressive and likely the best choice when the material has prominent weld spatter and height [4].
Next, using light grinding and blending discs on the metal can minimize the peaks and valleys. The ideal outcome is to have a consistent pattern characterized by a small distance between the peaks and valleys. When the peaks are too deep, they’ll fill with paint and increase the overall time required to cover the surface. However, the paint may flake off when the peaks and valleys are too small.
It’s also essential to consider that using an overly coarse abrasive at the start could prove counterproductive. That’s because when people need a smooth finish, a coarse-grit abrasive could create deep scratches in the metal that take longer to remove during later steps. The alternative is to use finer grits in the first step. Doing that may take longer initially, but it could remove some other steps.
Some fabricators also opt to use orbital sanding discs in their second or third steps when preparing to paint metal. Doing that creates a circular pattern in the metal. However, working with a random orbital grinder next could make that aspect of the surface less noticeable by breaking down its peaks and valleys.
When people work with new abrasives while preparing metal for painting, they should also experiment by using the products on pieces of scrap metal or non-critical parts. Such tests let them gauge the results without dealing with costly unwanted outcomes.
