Today, more manufacturers are making the switch to powder due to performance advantages like advanced corrosion protection, edge coverage and lower volatile organic compound (VOC) content due to global efforts to reduce harmful emissions and hazardous waste.
In fact, for these reasons and more, powder is one of the fastest growing classes of coatings used today.
Because it is an electrostatic process that applies electrically charged paint particles to a grounded part, powder has excellent adherence to metal substrates.
But newer generations of high transfer efficient (HTE) powder coatings take that coverage to the next level by improving first-pass application build rates, the percentage of powder that gets deposited on the part.
These specialized coatings deposit powder consistently and uniformly across complex parts and are formulated to electrostatically wrap and penetrate into deep recesses or hard-to-reach surface, achieving first-pass efficiency rates of up to 85% or better.
Compared to standard powder coatings, these systems can reduce powder consumption by 20-25%.
Of course, there are several ways to improve first-pass application build rates, including regular equipment maintenance and refining application technique. But transitioning to new generations of high transfer efficient solutions help to achieve optimal performance.
Virgin Versus Recycled Powder
A common misconception among coaters that have powder reclaim systems is that high transfer efficient technologies are less important than they are for spray-to-waste coaters. But HTE solutions have advantages for both types of operations.
First, reclaiming powder may not always be feasible, depending on the capabilities of the coater, the number of colors used and economic factors like time, labor and the quality of the powder.
Secondly, increasing first-pass build rates means that more virgin powder is used, which is typically of higher quality in terms of film build consistency, electrostatic charge, transfer efficiency and cured film appearance than virgin-reclaim blends.
Newer High-Transfer Efficient Powder Coatings
Because more powder clings to the part, high transfer efficient solutions produce less overspray so there is less waste to manage or reclaim, saving both time and labor.
Coaters that transition from standard powders to specialized high transfer formulations make significant first-pass application gains through the chemistry of the coatings itself, helping to overcome variables like application technique, equipment and operator skill.
The result is reduced product loss, more uniform film builds across the part, even on complex shapes, sharp edges and hard-to-reach areas, plus improved operational efficiencies and cost savings.
“These high transfer efficiency solutions take a lot of the guesswork out the application process and give applicators a greater degree of control over cost and quality of their production processes,” said Shelley Verdun, PPG Business Manager for Powder Coatings, Americas, Industrial Coatings.
PPG has a portfolio of powder coatings that are specifically engineered to deliver first-pass transfer rates 20-30% higher than standard powders for architectural building products and general industrial applications like shelving and racks, office furniture and heavy-duty equipment.
The PPG High Transfer Efficiency Line-Up
PPG ENVIROCRON® HIGH-TRANSFER EFFICIENCY (HTE) powder is specifically designed to provide excellent adhesion and durability on tricky parts and equipment such as wheels, wire racking, metal shelving and products with complex shapes.
Boasting first-pass transfer rates of 85% or greater, PPG Envirocron HTE powder can reduce per-item powder consumption up to 25%, lowering material costs.
- 85% first-pass transfer efficiency
- 20-25% reduction in material usage
- 50% improvement in booth cleaning intervals.
A patent-pending breakthrough in architectural extrusions and sheet aluminum, PPG CORAFLON® PLATINUM fluoroethylene vinyl ether (FEVE) fluoropolymer powder coatings offer high transfer efficiency rates of more than 20% and improved corrosion resistance compared to standard FEVE powders.
Meeting FGIA/AAMA 2605 specifications, the highest standards for weathering and corrosion resistance in the industry, PPG Coraflon Platinum delivers a fast film build and produces very little waste, even in difficult-to-reach cavities.
· 20% higher transfer efficiency than standard FEVE powders
· Wide range of colors and textures, including new anodized finishes
· Expanded gloss range of 5-85 compared to standard FEVE powders
· Specially formulated without major substances of concern
PPG makes two additional HTE coatings for the architectural industry, PPG ENVIROCRON® HTE (03) and PPG ENVIROCRON® HTE (04) that meet FGIA/AAMA 2603 and 2604 specifications, respectively. Both powder coatings deliver transfer efficiency ratings of up to 85%.
· Available in range of colors, glosses, and mica and metallic effects
· Waste saving first-pass transfer efficiency of up to 85%
· Energy savings 10-minute cure at 350°F (177° C)
· Good film integrity, impact and mar resistance and color control
Real-World Application of Specialized HTE Formulations
After PPG Coraflon Platinum powder was launched in the spring of 2021, a leading window manufacturer conducted trials to evaluate the formulation on their line and the finish.
The company applied Coraflon Platinum powder to a difficult-to-coat, geometric-shaped part using the same automatic powder coating line, line speed, air pressures and voltages as their usual standard powder process.
What they found was that the high transfer powder deeply penetrated into the recessed areas without heavy edge build up. Even after lowering the powder pressure by 20%, a much better first pass transfer efficiency was achieved, without sacrificing required film thickness.
By transitioning to a high transfer formulation, much less powder is going through the reclaim system and overall powder consumption has dropped by 20%.
While making the switch to an HTE formulation is optimal, there are other steps that can help to reduce application costs, improve application efficiencies and improve finish durability and quality.
Equipment Maintenance & Applicator Training
Optimizing spray application coating equipment and operator technique are two ways to increase first-pass build rates.
Because of the abrasive nature of powder and the possibility of creating impact fusion, spray equipment requires routine maintenance to maintain proper control of the application process. Applicator nozzles, pumps and guns that are worn or have impact fusion can clog and hamper air flow, leading to higher material usage, inconsistent powder output and defects in the finish.
Keeping spray guns, booths and racks clean is important, as is training employees to operate spray equipment properly and improve application techniques.
It’s also important to make sure that the part is properly grounded to maximize transfer efficiency. Poor grounding of the metal substrate is one of the most common causes of insufficient film build.
A full inspection of the application setup to ensure hooks are clean and all grounding wires are properly attached should be performed continuously.
Properly grounded parts are critical for an exceptional finish and optimal transfer efficiency.
Climate Controlled Storage
Beyond storing powder in a tightly sealed container to lock out moisture and contaminants, there are steps that help to maximize the shelf life of powder and its performance.
Since high humidity can negatively influence powder’s fluidization and flow, the recommended temperature range for storing powder is 60°F (15°C) - 80°F (27°C) with 40%- 60% relative humidity.
Beyond Better First-Pass Build Rates
These steps, coupled with the addition of a coating specially formulated to increase first-pass powder build rates, go a long way in helping applicators increase throughput, reduce waste and more readily achieve environmental compliance.
While PPG is a recognized leader in powder innovation, the company is one of the only complete solutions providers in the world with coatings in every major technology platform, including liquid, pretreatment, and electrocoat.
Click for more information on PPG Envirocron HTE powder.
Shelley Verdun is the PPG Business Manager, Powder, Americas, Industrial Coatings