How To Do A Better Job In The Paint Booth
Every year thousands of people paint themselves with oil and head off to Hawaii's warm air and blue water because they like the environment. Oil and water have no place in the paint booth, however. A smart shop owner will keep the finishing area clear of both water and oil, and will make sure the air is as pure as an ocean breeze.
Not every job will be perfect. A shop that is running two percent to four percent complaints (two to four major problems in 100 jobs) is doing a darn good job. The average acceptable job will have five to 10 pieces of dirt somewhere in the paint. The key to success is to reduce the number of flecks and fish-eyes. That is done by eliminating the major trouble areas.
Barry Thomas, general manager with DeVilbiss Spray Booth Products in Atlanta, identifies five major areas of concern with any paint job: vehicle preparation, the operator, the compressed air system, the paint booth and the paint itself. In that order, they are the most likely culprits in a bad paint job.
It is the simple things that are more apt to cause trouble with paint booths. Take, for instance, the door to the paint booth. Is it ever left open? "Lint and dust will float for days and always end up in the paint booth," says Jimmy Harris, national project manager for Garmat USA, in Englewood, Colo. "The worst thing you can do is leave the door open. Keep it closed."
The logic is simple. Once the fan is turned off in the booth, air will go out the intake. Any paint booth is always going to be hotter than the shop - with baking going on at 160 to 180 degrees Fahrenheit, the heat will rise, the air will sink, and all of that dirty air is reverse-vented into the shop.
Another possible trouble area is the hoses used on guns. They were not really meant to be baked to 160 degrees over and over again. Eventually, they begin to flake inside and those black flakes can make a mess of that pearl-white finish on that Buick. The answer, of course, is to change the $30 air hose and save $1,000 in buffing.
Dust comes from the strangest places, and not just fender cracks or body panel joints. A typical paint room produces 100 to 150 linear feet per minute. A paint gun will operate at 600 feet per minute, so anything on the walls will be blasted off by the gun and onto the job faster than the room can handle it.
Roger Koplin, sales manager with Viking Spray Booths, in Irvine, Calif., says that many of the booths from Europe do not produce a sufficient air flow to do the job. He says booths should be designed to exceed 100 linear feet per minute. "Most European booths are capable of only 65 to 70 linear feet per minute," he says, adding that there is no practical way to upgrade the airflow.
He notes that it is not heat, but airflow, that spreads and dries the paint. "Without the right airflow, all you end up with is a caking effect - like the skim crust on top of a heated glass of milk." This will become more important as manufacturers move more to thicker paints. "You can't finish a DuPont high-solid paint with a DuPont solvent-based paint," Koplin says. "They don't match."
Dave Phillips, engineering coordinator for Hankison International in Cannonsburg, Pa., says one secret to getting a quality paint job is improving the quality of compressed air used. He suggests that shop owners either get technical assistance or get educated on compressed air systems and the dynamics of compressed air.
"Ninety-eight percent of the equipment presently available is marginal in design and marginal in performance," says Phillips. Hankison, which specializes in 20,000 cfm (cubic feet per minute) systems, also offers small shop-sized setups. Phillips says purchasers need to know what they are looking for before they buy and should look for a dealer who will let them test out the equipment they are buying.
People Problems
In shops with just one painter, assigning responsibility for keeping the paint booth clean is simple. However, many shops have several painters and helpers. Each depends upon the others to keep the place in ship-shape, the result being that nobody is really responsible and the job does not get done. The solution is cheap: assign one person to be responsible - someone who is not buffing or sanding.
"I'm a painter myself and I know painters don't care for one another," Garmat USA's Harris says. In fact, he is a super-painter. Harris won Chevy's Customer Satisfaction Index (CSI) award three years running in the early 1990s. One year, he posted a score of 98 in a field where the national average for a painter was 42, and he was named General Motors' number one painter in the United States - so he's "been there" and understands the painter's perspective. "Unless someone has cleanup as part of their job, it won't get done or it won't get done right," he says.
Filters
It is also important to use quality filters. Alex Moldvan, vice president of Spraybake Ltd., Toronto, says collision people should beware of the attraction of inferior filters offered at cheap prices. "No matter who you bought [the paint booth] from, stay with filters from the original equipment manufacturer," he advises.
Good filters today generally will keep the air clean. Use a filter in the five micron to 10 micron range for the typical job.
While Steve Hagan, president of Air Filtration Company Inc. of Corydon, Iowa, would agree that filtration to the five or 10 micron range is sufficient, he notes that it is more important to be sure that a booth has the right filters. "Many filter companies make filters that will meet the needs of a spray booth," he says. "Be sure to use the right one for the job."
Hagan says that newer, thinner coatings dictate filtration to five microns. Below that, however, does not matter since a smaller particle is unlikely to be seen in the finish.
Timing of filter changes is, in large part, dependent on the environment. A shop in the country, surrounded by fields, will need to change filters more often than one with a less dusty environment. Filters on old cross-draft booths which draw shop air will clog faster than those in the newer booths.
In a average shop that does one car per day with a couple of smaller side jobs, the main filter should last three to six months. Pre-filters, which help the main filter last longer, should be changed more frequently - perhaps every three to four weeks.
Lint And Fiber Problems
"The biggest area for concern is the chem wipe materials used in vehicle prep," Thomas says. "The wipes break down and leave fibers behind."
Cotton mops can be another source of trouble. A technician may think he is being extra-careful by mopping the floor after every third or fourth paint job. But he'll use a cotton mop. "The only thing to use is a sponge mop," says Harris.
In fact, a tech trying too hard to keep things clean often will end up putting more dirt into the paint than he takes out. If a paint booth is working correctly, let it do the job it was designed to do.
Most manufacturers look for a multiple approach to keeping the paint area clean. A refrigerant drier for the compressed air system will take care of general removal of air and moisture. The coalescent part of the system ensures removal of oils. At the point source, there should be a desiccant drying system, as well.
"Look for equipment that can remove water vapor as opposed to equipment which removes liquid water," Phillips advises. He says there are three techniques for removing vapor: refrigeration, desiccation adsorption and selective separation via a semi-permeable membrane. While he says the latter is truly space-age technology, he adds, "In nine out of 10 cases, it is not suitable for the smaller body shop."
Speed It Up
One good way to reduce problems is to keep jobs out of the downdraft paint booth. Moldvan says infrared is the way to go with smaller jobs - and spot jobs now are about two-thirds of what a shop sees.
Whether baking a whole car or just a spot treatment, it still takes 25 minutes to get the job done. By using infrared, the job can be baked in just 10 minutes and the booth is available for other jobs. Both medium-wave and short-wave technologies are available. However, the shorter the wave, the faster the curing will take place.
Koplin says shops using any sort of spray booth should be certain to seal the concrete floor. "A concrete floor will draw dirt if it is not sealed," he says. "Booths operating at a negative pressure will draw dirt from everywhere."
A shop owner for 15 years, he refutes those who claim that negative pressure systems effect the paint job. "But you do have to put a cleaner auto into the booth," he says. "You have to be a better housekeeper."
A last tip is to avoid the processes that cause problems. "We'd go a year without buffing a car. People hate to see those circles on the surface, anyway," Harris says. His solution was to spend an extra 15 minutes beforehand washing and cleaning the vehicle. "The 15 minutes you spend cleaning now will save three hours of buffing later," he says. Not only are hours saved on the job, but cleaning requires a lower skilled worker and frees up others for more valuable tasks.
What To Do If Troubles Continue
If difficulties persist, it might be time to call in the "dust-busters." These are professionals who will give your booth and spray system a professional contamination analysis. Major firms like DeVilbiss work with their local distributors to run the check. Garmat's Harris also performs such testing.
They will set up sample panels around the paint area and run them through a laboratory for a microscopic analysis to determine the type of contamination that is causing the trouble and then go back to pinpoint the likely cause of the problem.
Something as simple as paint spits may be due to failure to clean guns properly. Air flow meters will be used to analyze the equipment. They will measure temperature and humidity in the booth area.
On the other hand, it may take one of the new laser particle counters to perform a particle analysis of the facility. These units will sample the air and count the number of particles over 10 microns.
Look to spend something in the area of $500 for a complete analysis of a typical facility. "No paint shop is going to spend $5,000 for a portable laser tester," Garmat's Harris states. "Hire a professional who has all the equipment you need to test everything in the shop." Not only will a pro have the right equipment, but he'll also look at the operation differently that an employee. If the test eliminates a single re-paint, it'll more than pay for itself in saved time, money and customer satisfaction.
Curt Harler is a technical freelance writer.
ASA Discusses Air Quality Standard With EPA || How To Do A Better Job In The Paint Booth || Cooling System Maintenance Helps Prevent Summertime Overheating || Proactive Target Marketing: Rethinking Your Business Strategy || Technicians Play A Key Role In OBDII Acceptance Success || ASE Celebrates 25 Years || Guest Editorial: Growing Your Own || Tech To Tech || Tech Tips || News Briefs || Taking The Hill || Around ASA || Shop Profile || Net Worth || Chairman's Message
AutoInc. Magazine ®, Vol. XLV No. 6, June 1997