Transitioning to Powder Coatings: What You Need to Know

Powder is Offering a Smoother Path to Sustainability and Efficient Operations
Powder coatings have reached a critical stage in their evolution since their inception in the 1940s. From the early adoption era of the 60s and 70s to today, advancements in powder coatings have accelerated, making the coatings technology more beneficial than ever before.

While there are applications where liquid paint excels, such as metallic finishes or when very thin films are preferable, the benefits of powder coatings are expanding and garnering more interest among applicators and manufacturers.

Due to exceptional performance features, application efficiencies, and sustainability advantages, powder coatings are finding their way to a growing number of OEM and coatings facilities worldwide.

Before contemplating a switch from liquid to powder coatings, there are many operational and performance factors to consider. What advantages do contemporary powder coatings bring to my products? What does it take to transition to powder, and how difficult and costly is the process? Is the technology a good fit for my applications and finishing operations?

Two primary factors driving demand for powder coatings are environmental advantages and advancements that are amping up the protective performance and durability.

1. Sustainability: Unlike liquid coatings, powder solutions generate less waste and produce little to no VOC emissions, which are heavily regulated in industry today.

2. Performance: Powder coatings offer exceptional durability that extend the performance of the finish and the longevity of the coated parts.

Ushering in a New Era
One reason behind powder’s popularity boom in recent years is the requirement for coating facilities to comply with strict limits on VOC emissions. Unlike conventional liquid coatings, powder coatings are formulated without solvents, which makes them safer to store and handle, eliminates hazardous wastewater byproducts in the finishing process (and the costs associated with managing it), and simplifies compliance with regulations aimed at improving air quality.

Additionally, with a reclaim system in place, powder overspray can be captured and reused by blending it with virgin powder, which reduces waste that might otherwise end up in a landfill.

Because they are formulated without solvents and are dry, powder coatings can be cleaned up with compressed air only, while solvent borne liquid coatings often require chemical agents and the management and disposal of wastewater.

The switch to powder solutions does come with equipment and installation costs and a learning curve, but the long-term benefits make it a worthy investment of time and capital for many operators.

In most instances, particularly in older facilities, a full conversion is necessary. This includes major modifications to current equipment or installation of all-new equipment like thermal ovens, spray booths, and reclaim systems.

When considering the cost of new equipment, the long-term value of powder coating efficiency and ease of use should be considered. Among contemporary finishing options, powder coating has the highest materialization rate of 95% to 98%. Over time, powder coating is a more cost-efficient process.

Energy savings from powder coating finishing can also help to offset costs of new equipment. On average, standard powder coatings require about 30 minutes in a thermal oven to cure, but low-bake formulations cure at lower oven temperatures and in less time (around 15-20 minutes); this can result in significant energy cost savings.

Organizations like PPG, through programs like Secure Launch Excellence^TM, offer comprehensive, step-by-step support for manufacturers transitioning from liquid to powder coatings and implementing new equipment into their manufacturing processes. PPG has a large network within the industry and can work with oven manufacturers, pretreatment facilities and others to ensure that new powder coating lines get up and running as quickly and efficiently as possible.

Production Efficiency
In terms of application, it is easier to achieve a thick, even coat with powder than with liquid coatings. This is due to the electrostatic application process where electrically charged paint particles are applied to grounded parts; there is no loss of thickness during the curing process since there are no solvents to evaporate; and film thickness can be more precisely controlled.

One important consideration in evaluating a liquid to powder transition is the impact on cycle times. Parts coated with conventional powder formulations typically require 30 minutes in a thermal oven (and less time with low-bake powders), followed by a brief cooling time. Once cooled, parts are fully cured and ready for immediate handling.

Many variables impact finishing speed including the thickness of the part, equipment, and coating chemistry. Manufacturers and applicators should conduct a full analysis to assess potential gains in production speed and finishing efficiency with a transition to powder coating systems.

Footprint Factors
Typically, powder coating equipment requires a larger footprint than liquid coating operations, primarily due to the size of ovens needed. However, powder thermal ovens can be designed to be more compact by incorporating infrared technology for heating the parts or by using low-cure powder formulations that cure in less time. This allows for shorter oven lengths, potentially reducing the overall footprint of the equipment.

Additionally, once powder coated parts are cooled, they are immediately ready for shipping and assembly; no space is required to store them until they are fully cured and ready for handling.

Finally, powder coatings do not require the carefully controlled storage of liquid coatings since they are more chemically stable and less reactive to extreme temperatures. This can translate into smaller more flexible space requirements for storage of boxes of powder versus heavy buckets and drums of liquid paints that require strict environmental control.

A Difference in Application
Liquid paints are viscous by nature during application and create a tacky surface until cured. There is a greater risk of contamination from the environment when using using liquid paint because it is not fully hardened until the solvent completely evaporates. This makes them more vulnerable to picking up dust and foreign materials and the development of surface defects like drips, sags and pops during the curing process. A liquid coating is actively changing as soon as it is applied and will slowly cure as it sits on the substrate. Liquid is very dynamic and sensitive to fluctuations in temperature and humidity during the curing process, which can impact smoothness, distinctness of image (DOI), and adhesion.

Powder, on the other hand, is more resilient because it is a dry, chemically stable substance. Powder can theoretically sit on a substrate unchanged until heat is applied. Once cured, it is resistant to contaminants and other cosmetic blemishes.

Why Make the Switch?
While liquid coatings are valued for their smooth finish, they also tend to be “softer” and less resistant to impacts compared to powder coatings that are generally more durable with excellent gouge, scratch, and chip resistance. In terms of film thickness, liquid coatings are typically between 1 to 1.2 mil, while powder coatings are generally around 2.5 mil or more. A thicker film helps powder coatings to create a finish that more closely resembles the traditional aesthetic of liquid paint but with more robust protection.

Powder Paving the Way
Making the transition from liquid coatings to powder formulations can deliver significant advantages in terms of smaller carbon footprints, simplified regulatory compliance, higher productivity, and more durable products. But it’s important for manufacturers and coaters to perform a cost and operational analysis to ensure that the transition is efficient, successful and worthy of the investment of both time and capital. Energy use, labor needs, maintenance, and material costs are important parts of this equation.

Powder and liquid coatings both offer advantages. Deciding which technology to use requires careful consideration of the substrate, the end use, cure requirements, and desired aesthetics including sheen, color, and texture.

While powder coatings still hold a smaller share of the market than liquid coatings, the technology is experiencing significant growth, driven primarily by efforts to minimize VOCs, and powder’s durability. Today, many industry innovators and stakeholders are beginning to see powder as the best path forward for their operations and their products.

Contact PPG and make the switch to industry-leading powder coatings.