Powder coatings are an important part of manufacturing durable parts, but when you have a threaded hole you don’t want coated, you need a way to cover it. Fortunately, there are a few ways to mask threaded holes for powder coating and keep the application accurate. Use these methods to cover threaded holes and powder coat materials without worrying about ruining the opening.

The Purpose of Masking

Manufacturers apply a finish to many metal and plastic items to improve the parts. Typical finishes include powder coating or electroplating that spreads across part of or most of the material. When you don’t want an area of the item to have a finish, you must mask that area.

Masking covers the part and prevents a finish from applying to the area’s surface, retaining its original appearance or functionality. Many manufacturers use masking to take advantage of its various benefits.

The Benefits of Masking

Masking improves a plastic or metallic piece in numerous ways. For example, the coated piece will sport a unique aesthetic appearance due to the contrasting surfaces. If you use a powder coating with a particular dye that differs from the color of the metal, you can create an interesting design.

Additionally, during electroplating, the integrity and function of an object may change as the electric current transfers cations. Maintaining the object’s properties may be an important aspect of a product. Masking and preventing certain parts from changing makes strengthening certain areas easier.

The Best Way To Mask Threaded Holes

Threaded holes present a minor challenge in masking when adding a powder coating to a material. You must cover each thread and prevent it from receiving the coating. Otherwise, you risk making it difficult to screw in a threaded piece later.

The best way to mask a threaded hole prior to applying a powder coating is by using plugs. Plugging the hole will prevent the powder from reaching inside, and, depending on the plug’s size, it can provide enough surface coverage to shield the threads and the hole’s edge. Plugs are typically deep enough to fit through the part or reach the bottom of blind holes, making them a functional solution for various threaded applications.

The Best Plugs for Threaded Holes

There are a variety of different plugs that have different levels of effectiveness in sealing openings. For a threaded hole, certain plugs will provide the best coverage to mask them during the powder coating process. Consider using these holes for your threaded holes so that you can apply the desired coating.

Silicone Plug

Regular silicone plugs come in various shapes and have some of the most universal functions in plugging openings. Thanks to their grooves, threaded holes aren’t the easiest to plug, but using a silicone plug will ensure the opening has a tight seal. Place the silicone plug in the threaded hole and twist it a couple of times to ensure it’s snug.

When you apply your powder coating, the hole will remain covered, and the powder will reach the edge of the opening. Silicone plugs are better for this process since they’re extremely heat resistant. When you heat the powder coating to make it stick, you can leave the silicone in the hole until the process is complete.

Silicone Pull Plug

A pull plug is useful for temporarily plugging a hole since it has a tab you may pull. Half of the plug is thick and fills a hole to prevent the powder coating from getting in, and the long, thin strand of silicone makes removal simple.

These plugs are a small step up from regular silicone plugs since they make removal easier. Removal may take more effort and tools if a silicone plug has little surface area to grab hold of. Use silicone pull plugs for an effective and straightforward way to mask a threaded hole for powder coating.

Leading Boss Plug

Boss plugs are special types of plugs that feature a unique shape to improve the coverage of threaded holes. The plug features a tapered end that enters the hole and an outer edge along its cylindrical shape that keeps it in place and provides more coverage to the opening. The rest of the plug is a long strip of silicone that helps people pull it out.

The tapered end ensures a tight fit in the threaded hole, and the raised edge along the lug creates an extra barrier during the powder coating process. These plugs come in a variety of shapes and sizes, making them useful additions to any coating process that requires masking.

Flangeless Plug

Accounting for the threads in a threaded hole requires a plug with ribs. A flangeless plug has the best shape to match a threaded hole design. Each rib and groove of the plug will fit into the threads of the hole and provide a great fit that seals the opening.

Twisting the flangeless plug is easy, as it resembles a threaded attachment fit for a threaded hole. These plugs typically have a uniform width, but longer plugs may sport a slightly tapered appearance to create a tighter seal as you screw it in.

Taper Plugs

The classic taper plug has many uses and benefits. A taper plug is an excellent tool for masking a threaded hole and providing better coverage. The plug’s rim covers the hole’s edge and ensures any coating doesn’t make it inside. Instead, any fluid or powder will pool inside the plug’s hollowed opening.

Twist the plug into the hole to ensure it remains snug and won’t come loose. A downside to this plug is that it may feel harder to remove because of the flat rim, but a flat tool easily solves this issue.

Consider the Thread Size Before Plugging It

Each threaded hole has a specific size you must consider before plugging it. The hole size determines what size screw, drill, or plug may enter it. Measuring the diameter of the fastener is the quickest way to determine the size of the hole.

Use a pitch gauge to measure the threads in the hole and how spaced out they are. Determining the size ensures you purchase the right plugs for your application before powder coating. Plastic pipe plugs offer the most benefits when you select the right fit, and knowing the threaded hold’s dimensions will help you avoid purchasing mistakes.

Powder coatings are fantastic additions to various materials, but when you need threaded holes covered, a plug is your best bet. Use these plugs for masking and consider how each option may help to mask the opening before you apply an additional coat.