Allow me to brag for a second: Kaser Blasting & Coatings has gotten really good at masking.
That’s because we’ve been asked to do it a lot recently, and through trial, error, and practice, we’ve figured out what works and, more importantly, what doesn’t.
Since masking adds time and cost to any blasting and/or powder coating project, I thought I would take a moment to explain what’s involved.
Masking a part for blasting is challenging because the blast process is very abrasive and the masking material has to hold up against whatever medium we’re using. We’ve found that several layers of high strength duct tape works best – if we mask with a single layer and accidentally roll across the masked area, the blast media damages the tape, and the masking will take forever to peel off. Imagine pulling shredded duct tape off of a part, tiny piece by tiny piece. Masking with 2-3 layers of duct tape protects the part more thoroughly, and peels much more easily when blasting is over.
Occasionally, a customer will mask their own part before bringing it in for blasting, using whatever tape they have at home. While I can understand the intention, it doesn’t actually wind up saving the customer time or money, because we usually have to redo it anyway. A poorly-masked part is not properly protected, and damaged masking takes forever to peel.
After blasting, we remove all masking, hang the part, pretreat it, dry it in the oven, let it cool, and then mask it again for powder coating.
There are a few reasons for this process: first, duct tape doesn’t hold up well to oven temperatures, so we have to switch to polyester film tape with a silicone-based adhesive before powder coating. Second, water from pretreatment can infiltrate any masking left on the part, causing it to fall off before we get to spray any powder. That’s why we’re very intentional about waiting for the part to dry before masking it again.
The tape we apply to the part before powder coating resembles a plastic polymer. It’s less sticky than duct tape, and slightly more rigid. It’s also more expensive. While this tape doesn’t require multiple layers, we do have to be very conscious about applying it in a manner than allows us to peel it after the part is cured. If we don’t leave ourselves a tab to pull, we’ll have a lot of trouble removing it from under the cured powder.
In short: masking adds a layer of complexity to any project. That being said, it’s completely doable, and we have a ton of experience with it. If you’re concerned about masking a sensitive part, give us a call!