A Guide to High-Temperature Masking Plugs
Whether you call them masking plugs, powder-coating plugs or powder-coat plugs, they’re indispensable when trying to achieve a high-quality finish. If you don’t use the right plug, high-temperature masking processes can damage your application. We’ll help you understand more in this guide, covering:
What are Masking Plugs?
Masking plugs are specialized components used in masking processes to block off or seal specific areas of an application that should not be exposed to the treatment or coating. Unlike masking caps, which cover the outer surface of a feature, plugs are inserted into through holes or cavities to provide a secure seal and ensure protection.
A high-temperature plug is used in masking processes that involve high heat, which is typically anything above 250°F (121°C). These processes include:
- Powder coating: A dry finishing process, powder coating involves applying a mixture of pigment and resin onto a metal surface using an electrostatic spray gun. After application, the coated part is cured in an oven, melting the powder to form a durable finish without the use of solvents.
- E-Coating: Also known as electrophoretic deposition, e-coating immerses a metal part in a bath containing a charged paint solution. Through the application of an electric current, the paint particles migrate and deposit onto the metal surface, resulting in a uniform and corrosion-resistant coating.
- Anodizing: Anodizing is an electrolytic process primarily applied to metal surfaces – typically aluminum – creating a protective oxide layer. By submerging the metal part in an electrolyte solution and applying an electric current, an oxide layer forms on the surface, enhancing corrosion resistance and providing decorative finishes.
- Plating: In electroplating, the substrate is submerged in a plating solution containing metal ions, and an electric current is applied to deposit metal onto the surface. (Electroless plating relies on chemical reactions to achieve metal deposition and is therefore not a high-temperature masking process.)
You’ll find it very helpful to learn about matching the right masking solution to the masking process. Our experts have put together Masking – A quick buyer's guide.
View our range of high-temperature masking solutions
What are the Different Types of High-Temperature Masking Plugs?
Types of high-temperature masking plugs vary to accommodate different shapes, sizes, and requirements of components according to the masking process. The masking plugs below are all suitable for high-heat processes.
High-Temperature Tapered Plugs
Tapered masking plugs are versatile and can fit into different-sized holes due to their design, providing a secure seal.
- Available as a solid plug or with a hollow core that aids compression for effective sealing
- Can be used multiple times
Material choices:
- Silicone, maximum temperature: 600°F (316°C). Color options include natural, blue, green, gray, pink, purple, red and yellow
- EPDM, maximum temperature: 435°F (218°C). Economical choice and boasts superior chemical resistance
Provides masking to the first thread of standard female threads.
- Ergonomic pull tab allows simple installation and removal
- Can be used multiple times
Material choices:
- Silicone, maximum temperature: 600°F (316°C) – premium material
- EPDM, maximum temperature: 435°F (218°C). Economical choice and boasts superior chemical resistance
Designed to mask holes without masking the surrounding surface area.
- Protects multiple hole diameters
- Ergonomic profile
- Pull tab for easy installation and removal
- Can be used multiple times
Material choices:
- Silicone, maximum temperature: 600°F (316°C) – premium material
- EPDM, maximum temperature: 435°F (218°C). Economical choice and boasts superior chemical resistance
Easy insertion and removal, making frequent masking and unmasking faster and more efficient.
- Available as a solid plug or with a hollow core that aids compression for effective sealing
- Can be used multiple times
Material choices:
- Silicone, maximum temperature: 600°F (316°C). Color options include natural, blue, green, gray, pink, purple, red and yellow
- EPDM, maximum temperature: 435°F (218°C). Economical choice and boasts superior chemical resistance
Designed to mask plain or threaded holes.
- Mask off the hole while allowing painting up to the hole
- Flexible fin design fits into a range of holes
- Silicone, maximum temperature: 600°F (316°C)
- Color options: Blue, green, and rusty red
Materials: Silicone vs. EPDM
When you’re talking about high-temperature masking plugs, your most effective options are silicone and EPDM. The choice between the two materials depends on factors such as the specific temperature requirements, chemical exposure, and budget constraints of the masking application.
Masking caps are also available in silicone and EPDM, but you can also get them in PVC and other materials. You can invert some caps and use them as masking plugs.
View our range of masking caps
To help you choose your masking-plug material, our experts have put together EPDM vs Silicone: A Simple Guide.
Read it. Use it. And if you have any questions, let us know. We also recommend you read Masking Materials Selection Guide.
Correct Sizing for Masking Plugs
Ensuring a proper fit is crucial for a seamless experience when using plugs. However, it's essential to acknowledge that measuring techniques differ based on the application. For instance, when installing into panels, considering panel thickness is key, whereas for standard holes, thickness isn't a concern.
For Panels:
When measuring a masking plug for panel installation, determine both the required diameter of the hole you’re going to plug, and the panel thickness.
For Standard Holes:
You only need to determine the required diameter and length to fill the hole. Diameter measurement follows the same method as shown here, with the length illustrated above.
Measuring for Tapered Plugs
Select a plug based on the diameter of the hole you're masking, aiming for the hole size to fall between the top and bottom. You want a plug where the hole size aligns close to the middle, ensuring ample material to enable easy removal from the hole.
For instance, if the hole diameter is 1.5”, choose a plug with a top diameter of 1.688” and a tapered bottom diameter of 1.406”.
While this process involves some trial and error, it's primarily based on measuring the hole's diameter. You can try before you buy with free samples from our range, so this should help make the process easier.
Note that any tapered masking plug's suitability may vary depending on your coating process.
Applications
The industries that commonly use masking plugs are vast. If the application has a hole that needs protecting to achieve a precise finish, then masking plugs are used. From providing protection for connectors, terminals, and circuitry in electronics to threaded holes and ports in machinery and appliances, masking plugs are invaluable. They can even protect medical devices during sterilization.
You’ll also find masking tapes incredibly helpful for applications involving irregular shapes or complex geometries. See our expert guide, How to choose the right high-temperature masking tape.
View our range of high-temperature masking tapes
Download free CADs and try before you buy
Free CADs are available for most solutions, which you can download. You can also request free samples (some exclusions apply) to make sure you’ve chosen the right product for what you need. Same day dispatch for sample requests received by 4pm.
If you’re not quite sure which solution will work best for your application, our experts are always happy to advise you.
Request your samples or download free CADs now.
Questions?
Email us at sales@essentracomponents.com or speak to one of our experts for further information on the ideal solution for your application 800-847-0486.