Rodger Talbert Columnist
Corrosion-Sensitive Environment
Q. I have some fencing around my swimming pool that has corroded badly over the years. It was made with steel and there is a lot of visible rust on the rails and vertical pickets. I am considering the options; have a professional painter come in and clean, repair and repaint the fence; or have the fence replaced with one better equipped to handle the harsh environment around the pool. What would you do if you were me?
Read More
Powder Coating Clinic: Adhesion Problems on Chromated Zinc Plating
Q. We have had adhesion issues when powder coating over zinc-plated aluminum. The aluminum had been nickel-flashed and zinc-plated with a hex-free chromate to meet RoHS compliance. Do you have any suggestions as to why the powder will not adhere properly to this surface?
Read More
Powder Coating Clinic: Solving Problems with Color Variation
Q. We are noticing differences in the color of parts coming out of the oven. It seems to happen more on some days than others. It can happen with any of our brighter colors like orange and red but does not seem to happen with more neutral colors like tan or gray. We use some infrared heaters in the first 20 feet of the oven and the rest is convection heating. We worked on balancing the oven but it is hard to get it level all the way through. What can cause color variation from part to part? How can we balance the oven and stop this problem?
Read More
Powder Coating Clinic: Oil Seeping out of Large Welded Tubing
Q. We have a large part made out of tubing that is welded together. The tubing has a lot of oil seeping out of the welds when the part is heated and causes a defect in the cured film. We cannot get the oil out of the tubing in our washer. We tried cleaning up the defect and running it again, but oil still runs out. How can we get that oil out of the tubing?
Read More
Touch-up Options for Powder Coated Parts
Is it true that powder coating cannot be touched up? Powder coating expert Rodger Talbert offers options for powder coating touch-ups.
Read More
Powder Coating Clinic: Powder in Layers
Q. We are in the process of designing a new powder system for aluminum extrusions and building panels. Our current system uses a six-stage dip pretreatment process and a three-layer liquid paint process (prime, color coat, clear coat) that meets AAMA 2605 standards (American Architectural Manufacturers Association). What layers of coating should we use and can we can meet the AAMA 2605 standards with powder?
Read More
Powder Coating Clinic: Making Powder Lines More Profitable
Q. We run a job shop powder coating operation with a conveyor system that runs at around 4 to 6 fpm, depending on what product is hung. We are putting through a lot of work, but our profits are not great. Can you suggest how to improve the efficiency, or cut our cost for a better profit margin? We cannot speed up the line because we do not have enough time in the cure oven to go faster. Our powder material cost seems to be higher than what we expect based on our quotes. What are we missing?
Read MorePowder Coating Clinic: Avoiding Rust on Parts
Q. We apply lighter colors of powder to our ticket machines for parking lots.
Read More
Powder Coating Clinic: Masking for Logo Design
Q. We are powder coating stainless steel water bottles for our company. For our logo, we would like to use a vinyl sticker or decal before powder coating. After the coating is applied, we want to peel the vinyl off to achieve a stainless steel logo effect, so we need some kind of temperature-resistant vinyl. Any suggestions?
Read MorePowder Coating Clinic: Discoloration of Metal-Flake in Powder
Q. We have a metal-flake silver powder color that we use regularly. If the surface is abraded with a Taber wheel—or even a pencil eraser—it darkens significantly in the abraded area. We even have this problem when our parts scrape against cardboard packaging. Our supplier suggested we switch from an unbonded leafing aluminum to a more expensive bonded product. We tried the bonded leafing aluminum, but we still have the same problem. Certain types of friction create this effect, seemingly those that perhaps have a higher coefficient of friction. Do they remove the aluminum flake from the surface? Can you explain this problem and tell us why it happens with some abrasives and not with others? What can we do to stop this?
Read More
Powder Coating Clinic: Measuring Film Thickness before Cure
Q. How can I tell if the powder film build is thick enough before I cure the powder coating? We coat a lot of square footage and we need to control our cost. We often put on too much powder to avoid light coating. I need to know what my uncured film thickness is.
Read More
Powder Coating Clinic: Sanding for Repair
Q. We sand aluminum die-cast parts that have minor defects in the powder coating before recoating them. The small areas of dirt, metal blemishes, fibers or similar particles are sanded using 120-grit sandpaper on an orbital sander. After recoating the parts, we often find more little specks and other defects and lines from the sanding disk in the coating. My question is, does this happen because of the sandpaper we are using, or because we sand all the way to the aluminum, exposing the surface and causing it to outgas?
Read More
