Boost paint transfer efficiency

July 10, 2015
Get advice from industry experts to ensure the best transfer efficiency, partnered with the best finishes possible.

As with any service business in the last two decades, the collision repair industry has undergone dramatic changes in the way it generates revenue. Looking back just 15 years, most shops were focused on boosting profits solely by bringing in more repairs, which typically meant pursuing as much work and as many direct repair agreements as possible. Stagnating labor rates and increasing costs in maintaining multiple DRPs made these course untenable for many repairers. Shops, quite frankly, were working harder for decreasing returns.

(Courtesy of SATA) Repairers need to make sure a spray gun is fitted with the correct tip for the product being applied.

(Courtesy of PPG) Correct spraying distance is 4-6 inches from the vehicle.

The focus then turned to lean operations, cutting waste to glean as much profit as possible from each job. Running lean quickly proved itself a money maker as shops began pocketing funds they once flushed away in the form of wasted materials and effort. In many cases, investments in lean operations were minimal. Shops didn't have to take special steps. They needed only to use their tools and products as manufacturers intended.

Of course, this remains the case today. Yet even with years of lean experience, the repair industry still struggles with implementing efficient operations in some areas. Nowhere is this truer than in the paint department, specifically with paint transfer efficiency. Spray gun and paint manufacturers regularly churn out new products designed to work together to provide better finishes using less product.

Through misuse, failure to invest in upgrades and other missteps shops frequently deprive themselves of optimal transfer benefits. Don't let this be the case at your business.

Refer to the following list of the steps to ensure the best transfer efficiency, partnered with best finishes possible:

Step 1: Get the right gun for the job. Is it time for your shop to update its spray guns? With some models carrying price tags approaching $1,000, shop owners can be reluctant to invest in newer technology, especially when proper maintenance has kept their current stock in great working condition. Painters may balk at switching to an unfamiliar gun while stepping away from a tool they're comfortable with.

Complicating this common scenario is the history some shops have with new spray guns. John Moore, Axalta Global Application Technology Guardian, notes that problems with early HVLP models produced doubts in the technology. "They under-atomized spray, which made color match and clearcoat leveling difficult." he explains. "There continues to be some reluctance to take advantage of the guns that are available today, even though they have an improved balance between atomization energy and paint flow."

Paint vendors encourage repairers to set aside any hesitation in purchasing new models or risk losing significant savings. Paul Evans, Zone Manager of Refinish Business Development Centers for PPG, says shops owe it to themselves to use the best tools available since are designed to work with the latest finishes to provide the greatest transfer efficiency.

Brian Stebbins, Regional Training manager for Sherwin-Williams Automotive Finishes, notes that newer gun models provide other significant benefits to a repairer's bottom line. They offer improved finish quality that requires less buffing and other post-paint work.

(Courtesy of PPG)  Spray guns must be fitted with a regulator, but air pressure must be set on the regulator at the wall for maximum efficiency.
(Courtesy of SATA) At least once a day, spray guns should be thoroughly cleaned, which means scrubbing out all the passages where product can dry and create clogs.

Pete Mahoney, National Technical Manager/Trainer for ChemSpec recommends shop demo a new gun for at least a week to allow painters to determine if the benefits justify the investment. Mahoney notes that some of the most recent gun designs have demonstrated significant increases in efficiency. He points to the Anest-Iwata Supernova, a low-volume low-pressure (LVLP) gun he says raises efficiency by as much as 20 percent. (Mahoney plans to test the SATA 5000 model, which also promises a significant boost in transfer.)

Even if repairers are willing to wait for newer guns, paint vendors say they can benefit from stocking multiple spray guns designated for each type of application. Doing so helps ensure the application type is applied correctly with optimal efficiency.

"Separate color and clear guns should be priority," says Prospray Technical Training Manager William Warner. "Dedicated quality spray guns should also be used for priming and sealing."   

Step 2: Set up the gun correctly. Regardless of which guns a shop selects, transfer efficiency will be tied directly to proper gun setup, especially with the selection of the correct fluid tip based on the product and job.

Evans notes, for example, that waterborne products typically require a smaller tip, in the 1.2-1.3 mm range, compared to solvent-based applications. When the wrong tip is used, painters end up applying too much product. This mistake costs shops twice since they lose efficiency and create texture problems and other finish deficiencies that must be fixed later.

Proper set up also includes utilizing the parts specifically designed for each spray gun brand. Shops should never use parts from one manufacturer's guns in another's. Evans says painters sometimes make the mistake of swapping regulators and gauges across manufacturer lines. While they may fit another brand, these critical gauges won't function accurately, thereby robbing the gun of its efficiency potential.

Step 3: Properly control air flow. Since optimal air flow is necessary for optimal transfer efficiency, painters need to avoid making five common mistakes that affect air volume and pressure.

(Courtesy of SATA) During a thorough cleaning, the gun needs completely disassembled, with the cap pulled.

Mistake one is using pressure in excess of manufacturer recommendations. Hans Kempf, North American Training Manager for BASF, says some painters still apply outdated notions of necessary air pressure requirements. "Painters tend to be creatures of habit, with some using excessive air pressure that's no longer needed in today's guns," he says. "Excess pressure causes product to bounce off a vehicle body, and it also creates increased overspray."

This mistake can be avoided by simply sticking to paint and gun manufacturers' recommendations. In fact, following these recommendations eliminates mistake number two, guessing air pressure settings. Evans says some painters adjust air pressure based on the sound of the air flowing from the air cap, a highly inaccurate practice that almost always wastes product.

Mistake three involves using weak or faltering air volume produced by underpowered compressor systems. "In some shops there isn't enough compressed air to go around for everyone using it," Evans explains. "The paint department always seems to be the last in line to receive air, and painters have to deal with sudden drops in pressure."

Without the necessary air volume and pressure, products don't atomize properly and produce "lumpy" or malformed textures. Some painters compensate by "going wetter"-- spraying additional product in an attempt to create the desired finish.

Others raise air pressure in an attempt to increase atomization. "What they don’t seem to realize is this not only wastes paint, it creates more potential overspray," says Warner. "It also contributes to bad looking blends, color flop, halos and lightness/darkness issues, along with color opacity that could be managed better with proper air pressure."

Evans says shops can head off all these problems by setting up a dedicated compressor for their paint departments or, at the very least, maintaining a dedicated compressor for the paint booth.

Going a step further, Stebbins recommends shops make the most of their available air by investing in high flow fittings and air lines. He also recommends regular maintenance of compressors to ensure optimal air flow at all times and to prevent oil and other contaminants from entering air systems.

From there, painters can avoid mistake number four by setting gun pressure at the regulator on the wall versus the air micrometer (or choke) on the gun. Kempf explains that when painters use the micrometer excessively to adjust pressure, they reduce the amount of air volume in the gun, cutting efficiency, while reducing gun pattern and atomization.

Finally, shops can avoid mistake five by setting proper spray booth air velocity. Moore notes that most new booths are designed to operate within the OSHA spec of 125-175 feet per minute flowing from the inlet filters toward the exhaust filters to efficiently remove overspray. The OSHA range also coincides with the recommended velocity for the maximum booth filter capture efficiency. Higher velocity, says Moore, causes excessive turbulence, which results in less product successfully making its way from the gun to the vehicle.

Step 4: Maintain your tools. Spray gun cleaning and care similarly should be performed according to recommendations. Proper maintenance not only extends the working lives of spray guns, it's a critical part of transfer efficiency. Stebbins explains that without regular cleaning, finish products can dry and gradually clog the gun's passages. As the passageways become smaller, painters typically compensate by increasing the amount of product they're spraying.

Effective cleaning should involve, at the least, a quick flush between every job, along with a thorough breakdown and cleaning at least once a day. That thorough cleaning must include removing the cap, fluid tip and needle and methodically scrubbing all the passages.

Step 5: Always be training. Training gives painters the opportunity to review cleaning schedules, along with gun set up, air flow and spray technique recommendations mentioned here. Just as important, it introduces repairers to constantly changing gun and product technology.

Warner notes that painters sometimes mistakenly regard their guns like modern fuel injection systems--needing little adjustment or attention--when their technology more closely resembles a carburetor, which requires regular fine turning that training addresses.

The same holds true for updated finishes, which painters similarly must adjust to in order to optimize finish transfer. Stebbins says training is vital for shops adopting new products or moving onto a different brand. The same rules that apply to mixing and applying one product can vary significantly between new generations and manufacturers.

Techniques change as well. Currently, recommended spraying distances run 4-6 in. from the vehicle body. Vendors note that too many painters adhere to  the outdated recommendations of 8-10 in., which wastes product.

Warner says painters also can increase transfer efficiency by adopting other techniques, such as creating tighter overlaps and limiting "wrist rolls" on blends to avoid building up dry spray on blend edges.

Together, all these recommendations can save substantial amounts of product. The key, as usual, is making sure they're put to work in your shop.