Mastering Design and Fabrication Defects with a Consultative Approach
July 17, 2024Which Metals can be Powder Coated?
August 12, 2024
When I encounter people who have an opportunity to learn more about powder coating (read customers and prospects), the conversation will often begin around the subject of the price to have their product coated a certain color. Color is the focus 99% of the time, at the expense of other details that will affect the performance of the coating and potentially the life of their product. Many peoples idea of powder coating is largely influenced by hobby shows which depict the central character having a piece of his motor bike / hot-rod / antique furniture / insert clichéd-metal-piece-here improved through powder coating.
There is a belief that powder coating is better. I loosely agree with this – without getting into a detailed conversation about coatings - however not all powder coatings are equal. This is further complicated by variance in surface preparation, coating chemistry, cure rate, and general handling. Unfortunately when a powder coater simply provides a customer with a color while ignoring these other aspects of a coating there is a chance that the coating will fail prematurely.
As custom coating shops, we know better.
For those of you who run a custom powder coating operation, you understand that metal type and condition, quality of fabrication, surface preparation, powder selection and application, cure schedule, packaging, and maintenance of the coating after installation all contribute to providing your customers with a coating that will meet or exceed the manufacturers design for the coating. And for those who still want just “black” – what gloss, texture, shade, and chemistry would you like?
In most cases when an engineer, architect, or fabricator has asked for “black” powder coating without any defined specification, it is the job of the custom coater to help them define the scope of the project to best identify what coating system meets the performance and price requirement. At Aegis, there are four areas that we focus on in order to define the appropriate coating system scope: Application and Performance, Coating System Type, Appearance, and Special Requirements.
The Four Quadrants
1. Application & Performance
The starting point for determining an appropriate coating system is to understand where the product is going to be used and how the coating is expected to perform. For example, a customer brings you a piece of hot rolled steel – is it enough to solvent wipe it and coat it? Maybe – if it is going into an air conditioned environment where it will never be exposed to temperature fluctuations, humidity, or impact. Conversely, if it is going to be used as an outdoor electrical kiosk in a coastal region, the coating will fail prematurely due to the mill scale cracking off from moisture and temperature fluctuations.
To define this part of the scope you should determine:
- What is the material? Steel, aluminum, die cast, etc.
- What is the weight?
- Where is it going to be used? Outdoors, indoors, enclosed, will people be able to touch it, etc.
- What will the environment be like? Dry, moist, humid, pH, immersion, high pollutant, seaside, temperature, etc.
- What is the expectation for the coating performance? 1 year, 15 years, long enough for a quick photo, etc.
It is impossible to cover all the variables that each question will pose because each custom coating job is so unique, the examples provided above are not presented as a complete list. When asking these questions, listen for hints in the answers that may prompt other questions.
For those of you who run a custom powder coating operation, you understand that metal type and condition, quality of fabrication, surface preparation, powder selection and application, cure schedule, packaging, and maintenance of the coating after installation all contribute to providing your customers with a coating that will meet or exceed the manufacturers design for the coating. And for those who still want just “black” – what gloss, texture, shade, and chemistry would you like?
In most cases when an engineer, architect, or fabricator has asked for “black” powder coating without any defined specification, it is the job of the custom coater to help them define the scope of the project to best identify what coating system meets the performance and price requirement. At Aegis, there are four areas that we focus on in order to define the appropriate coating system scope: Application and Performance, Coating System Type, Appearance, and Special Requirements.
2. Coating System Type
Armed with an understanding of where the coating will be used and how it is expected to perform, the custom coater should now be able to guide the customer in determining what type of coating system is appropriate. If you are not familiar with the properties of the coatings that you use, I highly recommend working with your coating supplier to inform and confirm your suggestion.
- Thickness: Depending on the chemistry of the coating you are applying you may need to be between 2.5 – 3.5 mils, or up to 12 – 15 mils.
- Type: Different chemistries afford different properties to the coatings we apply.
- Polyesters and Urethanes are both UV stable and suitable for exterior application.
- Epoxy coatings provide excellent protection from moisture and chemicals, and provide better edge coverage, but will chalk when exposed to UV and should be used as a base coat or for indoor application.
- Superdurable coatings will provide better color retention at the expense of some impact resistance.
- Antimicrobial, thermoplastic, FBE, Outgas Forgiving, and Hybrids are other types
- Surface preparation: Depending on what surface preparation equipment you have at your disposal will impact what you can offer to your customer. Based on their needs, which of the following is suitable:
- Solvent wipe and degrease
- Abrasive blast to one of the SSPC standards
- Galvanize
- Chemical pretreat.
- If the metal has been laser cut, do you have to remove the oxide that has formed on the edge?
- Have the welds been dressed and all weld spatter been removed? (abrasive blasting is not an effective means for removal of weld spatter)
3. Appearance
Going back to the customer that wants their metal powder coated black, there are not only different iterations of the color black, but there are also shades and chemistries to consider as well. If your customer has a specific color in mind it is best to have them send you a physical sample to have a match made up for approval. At this point, it is also best to inform them up front of what the potential cost is for a custom color match. In a previous issue of Powder Coating, Michael Cravens wrote an in depth article on visual appearance standards, I suggest you get your hands on a copy of it. In the meantime, you should get clarification from your customer on:
- What does an acceptable finish look like?
- Color
- Gloss
- Texture
It is also important that you help your customer have a realistic expectation for what powder coating is not meant to do:
- Fill gaps / gouges / cavities / etc
- Make welds look smooth
- Fill lap joints or any area where metal is sandwiched without a seam weld.
- Prevent pin holes in welds from weeping oil or other contaminants
- Penetrate deep recesses and coat effectively
- Effectively cover sharp edges
4. Special Instructions
Although vague, this is an equally important step in defining the scope for the appropriate coating system. It never fails that the seemingly small and insignificant aspects of a job can cause the most grief. It is best to determine from part drawings and dealing with your customer whether the following areas are applicable:
- Touch up paint required
- Masking
- Packaging
- Shipping
- Delivery requirements
Conclusion
Once the four areas above have been reviewed with the customer, and the importance of each area has been explained, then the price for what they require can be determined. This brings the custom coater and the customer into an area where the discussion then revolves around value, not price. In some cases the end result may be determining that what your custom shop specializes in is not a fit for the job that walked in the door, and that is a good thing. I believe that engaging in this conversation with our customers is an important part of the service we provide – and conversely when we do not we risk losing business and damaging the perception in our market of how powder coating performs.
A final point – any time we are talking about the performance of the coating system, it is in relation to ratings (salt spray, UV exposure, adhesion, etc) that have been measured in a controlled environment. We can safely talk in terms of salt spray hours, but should be very cautious to definitively say how many years something will perform in an unknown environment.
