Custom Masking Designs for Powder Coating and E-Coating

A common issue powder coaters and e-coaters run into is having their masking plugs pop out as heat results in built-up pressure.  One method of dealing with this issue is by implementing a vented design.

The way it works is by putting a slit into the plug, which allows pressure to release (without allowing the paint to leak in) and then closing up when the external pressure exceeds the internal pressure.

The image shown here is actually a "cross vent plug". That means the vent is covered up in a way that prevents shot blast media from entering the mask.  It's also a way of preventing extra powder from sitting out top, giving powder coaters the ability to get more uses out of the plugs.

Another method of venting out pressure is via a "pop-pin" masking method. The way it works is when enough pressure builds up, the top portion (the pop-pin) will allow the air/pressure to release without allowing e-coat / paint to leak in.

The pressure being released prevents leakages, but once the pressure escapes, the top pin comes back down to create a seal.

If you're looking to mask off a flat/mating surface that doesn't have anything to grab onto and don't want to deal with masking tapes, magnetic masking is a great option for powder coaters.

These are some of the fastest to install masking solutions you'll find, and it all comes down to the design and magnet that's used. We put a full overview on magnetic masking, which you can check out using the link below.

Powder building up (also referred to as "bridging") against a masking cap/plug is one of the big problems powder coaters deal with. There are several ways of reducing the chances of powder building up, but a common solution is to design a mask with a flange wrapped around it at an angle (like an umbrella or a skirt).

PPS plastic can also be used in high-temperature scenarios. One application could be where you'd mask a threaded hole and the grounding area.  The silicone washer acts as a high-temperature seal, while the PPS component works as a way of easily and consistently installing the mask and ensuring the mask stays in place.

Occasionally, a cap or plug just won't do it, which is why there are clamshell masking designs.  These masks work by wrapping around the product needing masked and then pulling pull plugs through to lock the design in place.

If you're looking for highly-engineered masking solutions (at least when compared to standard caps and plugs), this is a prime example. Expandable masks work by combining high-temperature plastic with silicone.  When the lever/handle is pushed down to the lock position, the plastic pushes out resulting in a tight seal around the component and the silicone.  This makes an excellent method of preventing leakage during e-coat.

A method of masking threaded holes can be by over-molding silicone onto a bolt.  This ensures a tight fit without the need to worry about the bolt's temperature resistance.  Like the image shown here, the silicone will typically be part of the design as a way of creating a seal and masking off the chamfered area.  This is also a great way of preventing plug blowout as well.

An alternative method to using one super long pull plug or two push plugs that may be at risk of blowing out is by switching to screw-together masking solutions.  As you can see in the image here, the design works by having a male and female component where the bolt portion goes in on one side and screws together with the opposite side.

The benefit of this method is you're able to hand tighten it to your desired needs to ensure no leakage will occur.  Customers are also able to use PPS as an alternative to metal bolts.

Custom molded masks are not always the best option, especially when it comes to lower-volume projects or crucial time constraints. In those cases, we recommend going with custom die-cuts that are shaped to your exact requirements.

A popular method of masking off bores and bushings now is by using custom-designed masking sleeves.  These require knowledge of rubber durometers, thicknesses, and design to get correct, but luckily our engineers are experts at these.

A common request we get is that our customers want to be able to hang their part by the mask. In order to do this, we add carbon black to the silicone to make it conductive, which then gives powder coaters the ability to hang the part.

Mating surfaces are commonly required to be masked off, which can be tricky without adhesive. When there is an opportunity to do so - such as a wheel's mating surface - we can develop custom-molded masking designs that make use of holes/threads/openings that also need to be free of coating.