Issue link: https://www.e-digitaleditions.com/i/941907
suggestions on this process would be helpful. T.T., Council Grove, Kans. A Hammertone powder coatings are formulated to provide a distinct look and feel. The vi- sual effect is created when the base color shows through the accent color as black craters of various sizes. This effect is ac- complished by the formulation and not by the application. Therefore, the look and feel is dictated by the powder sup- plier and not the person who applies it. This textural finish is useful in hiding surface blemishes on the substrate and providing an unusual appearance that is typically seen on electronic cabinetry. The hammertone effect is created in a single coat. The hammertone finish may not have the surface toughness desired by your customer, so they are asking you to apply a clear coat on top of it. The clear coat may be harder, more ultraviolet- light (UV-light) resistant, etc., to meet their coating performance goals. You should apply this coating in accor- dance with the supplier's recommenda- tion for surface preparation and coating thickness. Then, cure the part, as dic- tated by the technical data sheet. After cooling, the clear coat can be applied and cured, as recommended by the technical data sheet. Verify with the coating supplier that the hammertone powder coating has 100 percent over- bake resistance, as most powders do. This will ensure that the basecoat of hammertone isn't degraded when ap- plying the clear topcoat. You should also verify with the coating formulator that the basecoat and top- coat combination has excellent intercoat adhesion. The coating supplier should be able to tell you if any steps must be taken to prepare the basecoat before ap- plying the topcoat to ensure maximum adhesion between the coats. —N.L. Resolving a hanger problem Q Our company uses hangers that we make in-house out of 1/4-inch rod (because of the weight and configuration of our parts to be powder coated). We use them a number of times and really don't have a problem doing so except for one area where powder buildup makes it diffi- cult at times to remove one of the pow- der coated parts. We have been grind- ing the area of our hanger to help, but it isn't an easy solution considering our hanger configuration. We have looked into burn-off ovens, but at least at this point, it hasn't appeared economically practical. Again, it's just a relatively small portion of the hanger that's caus- ing the problem for us. Is there an easy way to remove the powder buildup in a particular area? B.H., Yakima, Wash. A Right up front, I don't have an easy solution. Of course, the benefit of powder coating is its toughness. And that means difficulty in cleaning hangers. If this problem is on a very small area of the hanger part attach- ment, a standard hanger cleaning sys- tem of most any type will be grossly ex- pensive unless you have some greater justification for it. I would work on attacking the problem before cure. I've seen vacuum systems used many times with great success. You can automate, or you can use a manual operation. A very small rubber hose, such as 1/4 inch or even 1/8 inch, could do the job. I suspect the 1/8 inch is too small to stay powder free for very long. You can control the amount of suction at the vacuum pump and pull away enough powder so that you can greatly extend the length of time before you need to clean the hanger. You won't eliminate the issue altogether, but you can certainly reduce the frequency of grinding or sanding the hanger. —G.T. Wearing PPE when powder coating Q Until a few years ago, our powder coating applicator in the spray booth only wore a respirator for protection. That's all the personal protective equipment (PPE) we used to require before the Occupa- tional Safety and Health Administra- tion (OSHA) came in and said we had to protect the entire employee with suits, boots, gloves, headpieces, etc. Our material safety data sheet (MSDS) had one statement in it that got us in trou- ble: "Contains a suspected mutagenic agent." After looking into other pow- ders, I found that a lot of MSDS con- tain that term. I know testing is done on all chemicals to protect the employee(s), but the attitude toward powder is that it is harmless and that statement doesn't mean much. Please explain why/what makes powder a suspected mutagen. Thanks. M.W., Newton, N.C. A As far as I know, the only pow- der formulation that has the words "mutagenic agent" in its MSDS information is TGIC (trigly- cidyl isocyanurate) polyester. This is but one type of powder coating available on the market. This mutagenic agent can only enter the body through inhalation or consump- tion. Human beings inhale through the nose and mouth and aren't normally disposed to eating powder coatings. Therefore, the appropriate protection device must be worn to protect this area of the body (that is, the nose and mouth). While powder coatings can af- fect some people with an acute sensitiv- ity and cause rashes and dryness of the skin, requiring gloves, suits, and head- gear, most operators only need breath- ing protection devices alone. However, if your operators are spraying within a powder coating booth enclosure, they must have the entire protection package to ensure safety and comfort. Having said that, federal OSHA stan- dards are enforced by local inspectors who may not have direct experience with powder coating technology. This puts some companies into a bind as they are forced to follow enforcement guide- lines that are stricter than other opera- tions require. Bottom line is you have to follow the requirements of local OSHA enforcement or educate them on the in- herent risks of the technology. Always follow the recommendations listed in the MSDS information to ensure that your operators are protected. —N.L. Powder coating two colors on a box Q We're powder coating energy meter boxes with gray on the outside and white on the in- side. Can you please suggest the proper way to mask the boxes so that we can do this type of application? The box is about 250mm long by 300mm wide by 170mm deep. The depth is achieved by a 100mm deep bottom box and a 32 POWDER COATING, February 2018