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22 POWDER COATING, February 2017 Removing the mask — Some tips and tricks to make your masking more manageable In my company, we focus primarily on jobs that require a two-coat system for long-term perfor- mance requirements. When it comes to masking, this presents unique problems that are not typical to most single coat masking operations. In this article, I will share experiences that our company has had in masking unique projects and some of the obsta- cles that we have had to overcome. To be fair, there are a number of different masking products available on the mar- ket and I am not an expert when it comes to the different types and appli- cations. I highly recommend you enlist the support of your masking rep to help you tackle your problems as they arise. Basics of masking W h e n w e a r e o n b o a r d i n g a n e w employee, the following points are some of the basics that we impart to them to make masking and unmasking easier. Leave a tab. Any time you mask some- thing in a straight line or wrap, start with the end in mind. By leaving an overhang of masking and folding it back in on itself, the removal of masking is made far easier once the job is done. Many ways to mask a part. At upwards of $12.50 for a 2-inch roll of green high temp masking tape, if you can find alternative ways to mask a job that do not negatively impact the quality, then do so. Aluminum foil (as shown in Photo 1), packing paper, and even cor- rugated cardboard (rolled up and insert- ed in a bore) can be suitable alternatives to high temperature masking tape. If the area is simple enough, you may even be able to cut something out of ply- wood (when blasting), significantly reducing the amount of tape required. What are you sticking to? Before mask- ing, ensure that the area to be protected is free of any grease, soil, oil, or any other contaminant that could interfere with the bond. Poorly adhered tape can come off during the cure and disturb the powder while it is setting up, result- ing in the need for rework. Part position for the win. Sometimes simply the way you orient the part can provide enough protection to eliminate the need to mask. This is typically only useful when masking for blasting (for example, resting a weldment on the ground on the face that needs to be masked prevents you from having to apply tape or cardboard to that area). However, on some pieces, you may be able to rack them back to back; just be sure to separate them while they are warm or you run the risk of bridging and crack- ing occurring between the two parts. Mind the gap. When putting caps on bolts or studs, do not push the cap all the way to the surface that the stud is welded to. Failure to do so can result in bridging of the powder from the part to the stud, and when the cap is removed there will be an ugly tear where the cap once was. (Note: The exception here is when you have a cap with a flange that is designed to leave a large area bare for purposes of fit or grounding.) Hardware. When given the choice, I will choose a screw or nut over a silicon cap or plug any day. By using the actual hardware to mask the area, you will be able to provide your customer with a much cleaner mask than can ever be achieved otherwise. If the job is ongo- ing, then you can burn the coating off once it accumulates and put the hard- ware right back into service for masking. Beware the blow out. If you are capping a blind hole (a hole that does not go through the part), be aware that there is a risk that oils trapped in that hole could expand and shoot your cap across your oven while the part is curing. This can happen quite easily on hinges as they are smooth and have no threads to grip the plug. By cutting a notch in the plug, you can give enough room for the gasses to vent without allowing enough pow- der in to cause an issue. Stop the problem before it starts — The custom fabricated mask A common theme in my a r t i c l e s i s t o a d d r e s s potential problems before they arise, and masking falls under this rule. If you have a cus- tomer that has asked for a quote on a project that requires masking on a flat or uniquely shaped surface, it may be worthwhile to approach your customer about making custom masking plates to reduce your labor time. Be aware that there needs to be some way on your end to easily fasten and remove the mask, and if the part is going to be hot when you remove the masking, then ensure that you factor this requirement into the custom mask design. We had one job with a variety of differ- ent diameter machined areas that were easily masked with thin gauge discs that were cut to the appropriate diameter, as shown in Photo 2. The handling of them was simple with the addition of a 3-inch eye bolt in the center that allowed for easy removal of the plate while the part was cooling down — mitigating any cracking of the powder during unmasking. In addition to the custom plates, we also found some oversized sil- icon caps to fit over large diameter hubs. Coater's Corner Coater's Corner Chris McKinnon Aegis Industrial Finishing