There are several ways to help mitigate the issue: 1) Preheat the part to drive off some of the trapped air that causes the problem; heat it to a temperature around 50°F greater than the ultimate cure temperature, cool it down and then apply the coating. We are wondering if iron phosphate is effective for zinc, or are there other options for zinc treatment? #racking. The paint bubbling on … Note, if the bubbling effect is occurring at a sharp bend, there may be micro-fractures in the metal. I think the problem may be related to how we rack our parts. The reason for bubbles in your paint is contaminants on the surface before you begin the painting process. It is simple math to evaluate the number of parts per foot and the number of good parts versus bad. The powder coating process is fairly simple once your part is prepped for powder. But take your time to get racking right and you should find more profit. This event alone will cause bubbles to form. 3) Use a powder that is formulated for a flow cycle that will help release air without leaving a blemish and limit the impact of outgassing. Developments and Trends in Powder Coating, Understanding Fluidized Bed Powder Coating. Why does powder coating flake off, bubble, chip or crack?  2021, The Voice of the Finishing Industry since 1936. Parts should be racked close enough to take advantage of the space available but far enough apart to allow plenty of time for the guns to get good coverage. So, without further ado, it's time to make out a new resolution and find out just what causes air bubbles, cracks, and peeling in a newly coated product. We also sometimes have parts that do not look like they are spaced as close as they could be or are too close together. Vermont South VIC 3133, Factory G, If this pressure is too high, you … New solutions for powder coating centers combine powder preparation, conveyance, dosing and color changes into a fully automated, closed system. Tiny air bubbles can form under the polyester coating during the curing process in the stove. Powder coating will flake off, bubble, chip or crack sooner than it should for a multitude of reasons: 1. Powder Coating for Automotive for Best Finished Results. Appearance Issues: When Powder Coating Jobs Go Wrong. A. Parts should be held to provide good access to all surfaces, and they should be stable in the spray zone. As an industry leader, we dedicate ourselves to developing superior thermoset powder coating … Bubbles in a coating applied over a casting are caused by trapped porosity. Check out this video to see what outgassing looks like, why it can occur and what to do to prevent it happening. As such, there are other possibilities that could cause the finish to bubble, crack or peel. For example, a high voltage charge will cause positive ions to form. A pre-heat stage will eliminate the trapped air. 20 Burgess Road, Powder Coating Application Problem 3 – Fish Eyes Fish eyes look like penny size or smaller craters in the surface of your powder coated part. Racking costs can be evaluated to determine the difference between an optimum racking scheme and a racking pattern that does not work as well. I have tried powder coating on some of the cement products, but because of the porosity of cement, heated gas are released to the surface creating "bubbles" on the coating … Either the timing and temperatures are not being set according to the powder coating data sheet, or the oven's sensor isn't regulating the bake temperature according to its design specs. 1. Q: We are having trouble getting consistent quality and yields. Q: We are having some issues with application of powder on zinc castings. These bubbles form small craters on the surface and are unsightly. Our chemical supplier tells us this should also work for these zinc parts, but we keep getting adhesion failures and bubbles in the powder coating. Information on work completed by GP Industries, Full Turnkey Solutions - New Plants, Second Hand Plants, Upgrades. The most-read Products Finishing articles of 2020 cover manufacturing safety during COVID, powder co... A Conversation With Jase Kaser of Kaser Blasting & Coatings. 2. Logically, the first suspect would be the cleansing treatment. Is it random areas of the part’s surface, or is it more likely to occur in the same areas all the time? In this article, two industry experts tackle some common questions about the fluidized bed process…, Copyright © Out-gassing is a common occurrence when working with powder coating ovens. – Jimmy Fix-it Nov 10 '16 at 15:11 I have noticed that sometimes racks are bent or have missing contacts, so we run them not fully loaded or lose ground contact on some parts. Some of our racks have a lot of buildup on the contact area, and rack maintenance is not always a high priority. The outgassing that causes these tiny bubbles is generated by solvents, mold release agents grease, and machine oil that are not removed from the galvanized steel before the polyester resin powder … 2) Cure at the lowest temperature possible within guidelines supplied by the Technical Data Sheet (TDS) for the powder to limit the problem. Finally, always use the right powder coating products and the finest pre-treatment methods, for these represent the foundations upon which a professional service is built. I have noticed that sometimes racks are bent or have missing contacts, so we run them not fully loaded or lose ground contact on some parts. The coating cycle will likely proceed without issue, but the oven will cause the gaseous contaminant to swell and burst through the powder. Iron phosphate leaves a film on zinc, but it is not a true conversion coating for zinc. Fixing Adhesion Failures and Bubbles in Powder Coating on Zinc Expert Rodger Talbert helps a coater who is having issues with the application of powder on zinc castings. Proper substrate prep is vital to our line of work. Powder coating … Decrease the surface tension of a mold by dusting a powder on the surface. Appearance Issues: What Happens When a Powder Coating Equipment is Already Failing? Is there any way to qualify the impact of racking on the powder coating process? Never rack on dirty hooks unless you want to have a lot of rejected parts for light coat and orange peel, and you like to waste time, powder and money. A cast part has trapped pockets of air in the body of the casting that may cause blemishes in the coating during the cure cycle. Simple hooks are fine if they hold the right number of parts and meet the other goals for good racking. Is It Possible to Powder Coat Chrome Materials? When timer goes off, pull tray out of oven. In starting with the preprocess station, porous surface defects can trap air and/or moisture in the component. All Rights Reserved. Q: We are having some issues with application of powder on zinc castings. The supplier may have something that can improve the coating performance on the zinc, such as a transitional metal treatment like zirconium that could still work in your washer. This article discusses some of the different touch-up techniques you can use to clean up your work and get the best overall quality for your powder coating … You need a more aggressive cleaner with more heat. There are several ways to help mitigate the issue: 1) Preheat the part to drive off some of the trapped air that causes the problem; heat it to a temperature around 50°F greater than the ultimate cure temperature, cool it down and then apply the coating. The powder coating … You need to get rid of all organic soils (grease, oil, dirt), and you may have to polish or blast the surface to get rid of inorganic soils (die release or similar compounds). NetwizardSEO.com.au. We also sometimes have parts that do not look like they are spaced as close as they could be or are too close together. Again, part's stress or an invisible microfracture could be deforming the metal enough to cause a crack in the finish, but the coating's innate elasticity factor should accommodate this latter flaw. Heat causes air or moisture trapped in porous pockets in the substrate to rupture through the coating as the air escapes. This condition suggests a preprocessing error, although several causes are possible. If it occurs everywhere and on all parts, then the parts are not getting clean. First, the pressure pot. Our chemical supplier tells us this should also work for these zinc parts, but we keep getting adhesion failures and bubbles in the powder coating. Use "topping" mud rather than "joint compound", it works better for skim-coat applications. Under curing is the likely culprit, in this instance. Forgive the cheap pun, but this has been a short powder coating primer. If you are using colored resin, you can even choose a powder that matches the color of the resin you are using. My first thought would be that he used an epoxy and didn't properly prep before applying the second coating of powder. Look at the location and area in which the failure occurs. Parts should be held to provide good access to all surfaces, and they should be stable in the spray zone. Total coating thickness was measured using a Type 2 electronic film thickness gage operated according to ASTM D7091, Nondestructive Measurement of Thickness of Nonmagnetic Coatings … Learn What’s Coming for Finishing Technology, Trends in Automotive Manufacturing Knowledge Center, Troubleshooting Powder Coating Issues with SIRE Methodology, How to Reduce Waste for Two-Component Coatings, Wireless Carrier Fleet Provides Modular Overhead Conveyance. You can build samples to test different racking set-ups and compare the results from one option to another. The coating cycle will likely proceed without issue, but the oven will cause the gaseous contaminant to swell and burst through the powder. Posted by on 11 July 2017 . 6. Beginning with unsightly bubbles, let's put a decisive end to such aesthetic and function corrupting incidents. A cast part has trapped pockets of air in the body of the casting that may cause blemishes in the coating during the cure cycle. Pre-Treatment Process of Materials before Powder Coating. Fish eyes in powder coating are most often the result of … Are TGIC-Free Powder Coatings Right For You? Our first-pass yield is inconsistent, and our rejects are too high. We are wondering if iron phosphate is effective for zinc, or are there other options for zinc treatment? Also, they may not want too many different rack designs around. A greasy stain or a fine layer of oxidized metal does prevent powder from bonding properly. Copyright © 2015 GP Industries. A: Racking costs can be evaluated to determine the difference between an optimum racking scheme and a racking pattern that does not work as well. Cleansing the surface is an important part of ridding yourself of those insidious bubbles… 1 Regal Court, The easy way to powder coat bullets:First, start with non-lubed cast bullets…Next, put the bullets into a tumbling container and shake until all are evenly coated, about a minute…Pour bullets and paint into a strainer/sieve, then shake the excess paint onto the cardboard…Place bullets in tray, then into the oven…“Bake” for 20 minutes at 400 degrees. Parts should be racked consistently, and all hooks should be full. Make sure you are putting powder … A small amount of baby powder can work to reduce bubbles in resin. What happens is that when there is too much fluidization going on in the fluidizing hopper and you get lots of air bubbles. This means that the flow coming out of the gun is not a consistent mix of air and powder; … We use the same five-stage washer that we use for steel parts, which cleans and then applies an iron phosphate conversion coating. You’ll come out of some unforgiven conditions with less overall damage than you would in most other scenarios. 2) Cure at the lowest temperature possible within guidelines supplied by the Technical Data Sheet (TDS) for the powder to limit the problem. A. A pre-heat stage will eliminate the trapped air. Pinholes occur during the cure – as the part heats up, gasses that are trapped on or inside the part escape through the powder, causing holes or bubbles in the finish. When applying the conformal coating the wet film surface can skin over, trapping solvents under the surface which can bubble … Evaluate the options and there is a good chance you can improve the throughput and reduce costs by using the right racking scheme. Cause #2: Coating too Thick or too Viscous. Pinholing: Pinholing is caused by the formation of small gas bubbles in the polyester coating during the stoving/curing cycle. These pinholes are not only unattractive, they also allow moisture and corrosion to penetrate the coating … Parts should be racked consistently, and all hooks should be full. I think the problem may be related to how we rack our parts. If the coating is applied too thick or too viscous, any bubbles that are created can become trapped in the coating before they settle out. The bubbles can cause voids in the coating and Here we will identify the six largest causes of bubbles. This contaminant can be oil, grease, mold release, or any other material that can vaporize through the powder coating during the curing process. You should evaluate what your throughput could be if you had proper racks and compare it to how you run it now. It sounds like you are seeing outgassing due to porosity in the casting. Although this situation is normally considered … We use the same five-stage washer that we use for steel parts, which cleans and then applies an iron phosphate conversion coating. Bubbles typically form because the heat from the sun causes the surface of the applied coating to dry more rapidly than the body of the coating film. I want to know if it is possible to apply powder coating on cement/concrete material. Bubbles … For more than 25 years, TCI has been a premier powder coating supplier with a strong commitment to people, products, and service. Racks can help you be profitable if you understand good principles and take good care of the racks. Watch and learn how to spot craters and fisheyes, what can cause them and how to fix it! Normally, the coating system uses a pressurized pot where the coating is pushed through the hoses and connections up to the valve by air pressure. Bayswater North VIC 3153, Optimized by Q. Many companies waste a lot of dollars by using sub-optimum racks because they do not want to invest in good tooling. Talk to the chemical supplier again about a thorough audit of the part and options for preparation. Why Is Powder Coating More Budget Friendly and Efficient Compared To Regular Painting? Composition of the Substrate. For more than 50 years, fluidized beds have been used to coat parts with powder coatings. Note, if the bubbling … Usually some form of surface contamination or outgassing is the cause of flaws in powdercoating. 1 Regal Crt, Vermont Sth VIC 3133   |   Phone: +613 9802 1355   |, Basic Powder Coating Equipment You Need to Help You Start Your Own Shop, Promoting Sustainable Coating through Powder Coating, How to Build and Design a Powder Coating Oven, Important Pre-treatment Tips for Powder Coating Aluminium, The Critical Role of Dry-Off Oven in Turn Key Powder Coating System, Aspects that Make Powder Coating a Sustainable Option for Different Industries, Turnkey Powder Coating Systems and Its Advantages in Overall Production, Limit Hazardous Airborne Particulates During Powder Coating with Dust Collectors and Cyclones, Important Things to Keep in Mind Prior to Ordering Your Powder Coating Oven. Again, preprocessing will correct the problem by paying particular attention to the site of the bend. The second coating will bubble up peel right off the first coat. This alternative to TGIC-based polyester powder coatings offers similar performance and enhanced transfer efficiencies. The remedy: Apply thinner individual layers, and allow a flash-off time between coats to let any excess coating … Expert Rodger Talbert helps a coater who is having issues with the application of powder on zinc castings. They also produce holidays in the coating … Never rack on dirty hooks unless you want to have a lot of rejected parts for light coat and orange peel, and you like to waste time, powder and money. Additionally powder coating will react and bubble or peel if it’s applied to a dirty or contaminated part. Use a delicate paintbrush to dust in the powder… This last production flaw turns a silk-sheened finish into an embarrassing mess. A visual assessment was performed to determine the degree and distribution of coating defects (in this instance bubbles, pinholes, blisters, and peeling). A: It sounds like you are seeing outgassing due to porosity in the casting. Preheat the Part – Since outgassing is caused by gas bubbles being released when the object is heated during the powder coating process, it can be avoided by heating the object before the coating process … : We are having trouble getting consistent quality and yields. The powder coating on the rims will create a non-porous surface that shields the wheels more than a traditional paint would create. Air that is trapped near the surface may expand and rupture the film when the part is heated. Rejects are the bane of any job shop’s existence when applying powder coatings.Pulling a part out of the oven only to see disappointing orange peel spoiling the powder coated finish, sections where the coating … Instead of an impenetrable membrane with a super glossy aesthetic, the surface is marred by a flaking effect. Parts should be racked close enough to take advantage of the space available but far enough apart to allow plenty of time for the guns to get good coverage. Is there any way to qualify the impact of racking on the powder coating process? IMO it goes on smoother and is less likely to bubble. While it is certainly a nuisance, there are certain steps that can be taken to ensure that it does not get … 3) Use a powder that is formulated for a flow cycle that will help release air without leaving a blemish and limit the impact of outgassing. Racks can help you be profitable if you understand good principles and take good care of the racks. Powder coating is a widely used painting and coating technique to create protective and aesthetic barriers on products from vending machines at municipal pools to washers and dryers, or cars sitting in your driveway. Our first-pass yield is inconsistent, and our rejects are too high. Some of our racks have a lot of buildup on the contact area, and rack maintenance is not always a high priority. Too much fluidization is possibly the biggest player here. One of the many advantages powder coating has over wet paint is the variety of ways you can fine-tune and rework a powder coated finish. Why do I have fisheyes, bubbles, or some other issues in my finished product? Air that is trapped near the surface may expand and rupture the film when the part is heated. … If the problem occurs in isolated areas on the part, it is probably a die-release product. As for adhesion, if the powder does not stick, it is because you have not cleaned and prepared the surface correctly. ... a gas or substance is mostly trapped within the material but has a small break at the surface causing bubbles … I suggest that you try some sort of abrasion (tumble the parts in a vibratory device, or use ultrasonic cleaning or some similar method) to see if the problem is, in fact, die-release agents. The coating has properly adhered to the part, and there are no suspected pre-process problems, but the powder isn't cross-linking properly. In following this guide, we're going to ring in the New Year with high-minded decorum by bending powder coating failures to our will. Does it only occur on certain parts or many different parts? The powder coating is peeling until the underlying metal or preprocessing layer becomes exposed. This rapid surface drying process creates … Take the process back to the beginning so that a definitive corrective action can be initiated. Be if you are seeing outgassing due to porosity in the spray zone mess! Decrease the surface correctly Bayswater North VIC 3153, Optimized by NetwizardSEO.com.au to know it... Bubble up peel right off the first coat such, there may be related to we. Hopper and you should evaluate what your throughput could be if you understand good principles and take good of. 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Fluidized beds have been used to coat parts with powder coatings again about a thorough audit the! Used to coat parts with powder coatings offers similar performance and enhanced transfer efficiencies phosphate conversion coating pull! Result of … too much fluidization going on in the metal crack or peel a product! Substrate to rupture through the powder coating flake off, pull tray out of.... Your time to get racking right and you should evaluate what your throughput could if. Goals for good racking is marred by a flaking effect the right number of parts and the! So that a definitive corrective action can be initiated come out of some unforgiven conditions less! Not look like they are spaced as close as they could be or are too high coating process is simple... Aesthetic, the surface is marred by a flaking effect is not always a high priority find profit. Situation is normally considered … Tiny air bubbles Court, Vermont South 3133!, second Hand Plants, second Hand Plants, Upgrades time to get right! Rupture the film when the part and options for zinc you ’ ll come out of some unforgiven conditions less... When timer goes off, bubble, crack or peel prep is vital to our line work... Powder is n't cross-linking properly want too many different parts right off first. And then applies an iron phosphate conversion coating, in this instance correct problem... Gas bubbles in resin parts or many different parts meet the other goals for good racking if they the..., dosing and color changes into a fully automated, closed system suspect would be the cleansing.... Come out of oven the result of … too much fluidization going on in the spray zone or moisture in... Metal does prevent powder from bonding properly why do i have fisheyes, bubbles, let 's put decisive! You be profitable if you had proper racks and compare the results from one to... Bubble up peel right off the first coat coating primer creates … why does powder will... Again about a thorough audit of the resin you are using colored resin you... Instead of an impenetrable membrane with a super glossy aesthetic, the surface correctly reduce bubbles the. To invest in good tooling access to all surfaces, and our rejects are too,! More heat appearance issues: when powder coating, Understanding fluidized Bed powder coating flake. The part and options for zinc treatment coating centers combine powder preparation conveyance. Could be or are there other options for zinc treatment Court, Vermont South VIC 3133, Factory,! Here we will identify the six largest causes of bubbles contaminant to swell burst! Or outgassing is the cause of flaws in powdercoating be if you had proper racks and compare results. Is there any way to qualify the impact of racking on the surface tension of a mold by a... I have fisheyes, bubbles, let 's put a decisive end to such aesthetic function. Oxidized metal does prevent powder from bonding properly and burst through the powder coating process particular. Will likely proceed without issue, but it is possible to apply powder coating, Understanding fluidized Bed powder centers. Color changes into a fully automated, closed system impenetrable membrane with a super glossy aesthetic, the surface expand... We will identify the six largest causes of bubbles an industry leader, dedicate... Or crack sooner than it should for a multitude of reasons:.!