A metal part can look right after powder coating and still be difficult to assemble. Threads may need to accept a bolt. Two parts may need to meet at a precise surface. A contact point may need bare metal. The solution is to identify these areas before the coating job is quoted.
Masking means protecting a selected area so it stays uncoated. It can be done with suitable plugs, caps, or tape, depending on the feature and the coating process. Echo Engineering explains why threaded holes often need protection. Your coating partner should select the method for the actual part; you should make the function of each area clear.
Start with threads and holes
Show every threaded hole and stud that will take a fastener after coating. Mark whether the hole goes all the way through the part or ends inside it. If a bolt must start flush against a face, point out that face too. A thread size and a photo help more than a note that says only “mask holes.”
Not every hole needs the same treatment. An unthreaded clearance hole, a threaded hole, and a hole that must keep a tight fit serve different purposes. Tell the coating shop what each one does after the part is finished.
Mark surfaces that affect fit or function
Look at the part as it will be installed. Does a bearing, gasket, bracket, or another component touch a particular face? Does an electrical contact need metal-to-metal contact? If so, mark that location on a drawing or photo and explain the requirement. Echo Engineering also explains why mating surfaces may need to remain clear and why grounding points require a deliberate masking plan.
There may be a tradeoff at the edge of a masked area: you want the part to fit, but you also need a clear plan for what remains protected. Ask the shop to review the mask boundary rather than assuming that every nearby surface should be bare.
Send a simple masking map with the quote request
For one custom part, a photo with arrows may be enough. For repeat manufactured parts, use a drawing with marked locations so every batch follows the same plan. Include:
- material and overall dimensions;
- quantity;
- desired color or texture;
- indoor, outdoor, or other service conditions;
- every area that may need masking;
- the date the parts are needed; and
- a sample part or mating component when fit must be checked.
Salt City Metal Coatings provides powder coating in Enoch near Cedar City. Request a quote and send the photo or drawing with your masking notes. We can review the part and discuss a practical finishing plan.