Painting Issues for Trailer Builders

TRAILER manufacturers have several issues to consider when painting trailers, said Jamie Miller sales manager at Valspar, a paint and metal coatings manufacturer in Grand Prairie, Texas.

Topics that trailer manufacturers often mention to Miller as he visits customers around the country were reviewed during a seminar at the National Association of Trailer Manufacturers 10th annual convention and exhibition in Las Vegas, Nevada.

The issues reviewed in the seminar were compliance with regulations for Volatile Organic Compounds (VOC), safety regulations from the Occupational Safety and Health Administration (OSHA), safety equipment, and surface preparation. Trailer manufacturers want more information about cleaning metal surfaces before painting.

Metal surfaces must be cleaned properly before painting, Miller said. The surface needs to be clean enough to expose hydrogen bonds on the metal. The chemical bonding supplied by acid-etch primers provides the best adhesion.

To adhere to metal properly, paint has to be within five angstroms of the metal surface, Miller said. An angstrom is three times larger than the diameter of an oxygen atom.

"We're talking very close to the metal," Miller said.

Paint adhesion is prevented by surface contaminants such as water, metal oxides, hydrates, salts, carbon deposits, and other compounds such as machine oils. These substances have to be removed so paint can bond with steel.

Cleaning Metal Surfaces Steel can be cleaned in several ways, including wiping it by hand with solvents or water-borne cleaners, Miller said. Alkaline cleaners such as degreasers also clean metal before painting.

Some of the first alkaline cleaners used to clean metal turns surface contaminants into soap, Miller said. If this soap is not rinsed away, it forms alkaline film that prevents the paint from adhering properly. New alkaline cleaners turn into liquid with a neutral pH that makes the surface inert.

Acid cleaners can clean anything an alkaline cleaner can, Miller said. Acid cleaners are mixed with phosphates and used in a single-stage cleaning process making them quick and inexpensive to use.

The best surface preparation for metal is sandblasting, Miller said. The benefits are that the metal surface is textured,and any contaminants are removed by the sand.

Pretreatments for metal include iron phosphates and galvanneal, Miller said. Pretreatments slow down corrosion, undercutting, and delamination, and provide a course structure that allows better paint-to-metal adhesion.

Besides surface preparation, another concern of trailer manufacturers deals with state and federal rules regulating spray booths, Miller said. Many states have individual plans for implementing Environmental Protection Agency (EPA) rules regulating spray booths.

Different State Rules "This is a problem for coating manufacturers because we have to produce the many different coatings required by different states," Miller said.

A trailer manufacturer in a state requiring an expensive, high-solids paint has a disadvantage compared to another manufacturer in a state with less stringent requirements, he said. A coating industry association is trying to level the playing field.

The National Paint Coatings Association (NPCA) represents 500 major paint manufacturers, suppliers, and distributors, Miller said. The NPCA expresses its concerns to regulatory agencies such as the EPA.

"It's hard to make coatings that perform well at VOC levels within some state guidelines," Miller said.

The NPCA advises the EPA of workable VOC guidelines, Miller said. In 1992, the NPCA proposed a national rule for VOC-emission targets for a broad range of coatings. The rule is scheduled to appear in the Federal Register in August 1998.

"The EPA adopted the NPCA proposed VOC guidelines largely intact," Miller said. "It went fairly smoothly. But it takes a long time to get things changed."

Proposed VOC Guidelines The proposed guidelines place more responsibility with the paint manufacturers because they produce the coatings that must meet VOC guidelines, Miller said. Currently, manufacturers can produce any VOC-level paint.

"Under the proposed VOC guidelines, it's the manufacturer's fault if someone purchases paint not in compliance," Miller said. "Paint manufacturers will be required to supply VOC-compliant coatings."

Each state has an administrative code that specifies which paints can be used, Miller said. The administrative code for Ohio is typical of rules found in many other states.

The Ohio rule sets a limit of 3.5 pounds of VOC per gallon excluding water and exempt solvents, Miller said. More restrictive rules in other states set a limit of 2.8 pounds of VOC per gallon.

Other state rules allow higher levels of VOC per gallon if the spray booth has a control system such as a furnace to burn excess solvent fumes. Another way to reduce solvent emissions is with chemical filters that can absorb VOC.

"I haven't seen regulations mandating VOC levels in paint lower than 3.5 pounds per gallon," Miller said.

In the Ohio administrative code, the section on surface coatings and miscellaneous metal parts and products is where rules are found for the trailer manufacturing industry, Miller said. According to Ohio guidelines, a miscellaneous metal part is anything except cans, coils, metal furniture, large appliances, and aluminum or copper wire.

Hazardous Air Pollutants Besides VOC emissions, trailer manufacturers must deal with another painting issue involving Hazardous Air Pollutants (HAPS), which is a federal government list of 190 chemicals, Miller said. These chemicals are considered to be hazardous to human health.

"Regulations are geared to lower the amount of solvents released into the air from spray booths," Miller said. "It is a separate issue from VOC."

Some paint-coating solvents on the HAPS list are formaldehyde, isocyanate, and methyl-ethyl ketone, Miller said. The federal government says these solvents are most hazardous to human health.

"Two common solvents that cause problems for the painting industry the most are xylene and toluene," Miller said.

HAPS are regulated as stationary sources if a large manufacturer emits over 10 tons per year of a single HAPS substance, or 25 tons per year for a combination of HAPS substances, Miller said. Companies that emit over 25tons are considered a major stationary source and regulators work with those com panies to lower their HAPS level.

Good reasons exist for regulating HAPS, Miller said. Some HAPS are suspected carcinogens. Lowering VOC automatically lowers emissions of HAPS.

In areas that do not meet EPA air quality standards, regulations will require using paint with VOC level of 3.5 pounds per gallon or less, Miller said. Rules also will require that HAPS emissions are below the 10-ton per year level.

Quality is Improving In terms of quality requirements, the coating industry is in compliance, Miller said. Urethane and epoxy paints have better quality and are longer-lasting than paints produced five or six years ago.

"Air-dried coatings are lagging a little behind in quality but are improving," Miller said. "These paints have a high-solid content compared to other paints."

In the future, exempt solvents will be used to make paint with VOC levels of 3.5 or 2.8 pounds per gallon, Miller said. Paints with exempt solvents will make it easier to paint trailers.

As determined by the EPA, exempt solvents are not hazardous to the ozone layer and are not photochemically reactive, Miller said. One of these chemicals is acetone, which is a very common solvent with a high evaporation rate. Adding acetone to a 3.5-VOC paint makes it easy to spray.

"Acetone is not the answer to everything, but it helps," Miller said.

A new synthetic solvent with a high evaporation rate similar to xylene is parachlorobenzotrifluorid, Miller said. Other solvents are being produced with good evaporation rates and cutting power. These solvents are very expensive, probably selling for twice what xylene costs.

Safety Equipment Issues When paints are sprayed or manufactured, employees are exposed to chemicals. Several rules affect paint producers and the trailer manufacturers using their products.

OSHA checks exposure levels of employees at paint manufacturing companies once a year, Miller said. The OSHA inspectors recently began checking exposure levels of employees at trailer manufacturing companies.

"In one case, a trailer manufacturer was inspected because a disgruntled employee reported the company to OSHA," Miller said.

Problems arise when spray booths without low airflow rates replace the air in the booth with overspray, Miller said. Air pressure inside the booth is supposed to be higher to reduce the exposure level for painters. Higher air pressure inside the booth protects employees, parts, and trailers from overspray.

As OSHA officials make inspections, they will be paying attention to the airflow of a spray booth, Miller said. To bring a painting operation into compliance, OSHA will require changes that include using different paint, using proper protection for painters, or replacing a spray booth.

Another safety issue is the proper use of respirators, Miller said. Sometimes painters wear the wrong respirator for the type of product they are spraying. The Right Equipment

Painters using respirators may be dressed in t-shirts, their heads are exposed, or they are wearing baseball caps on, Miller said. These painters are exposed to chemicals.

"We need to protect these people," Miller said. "These paints have solvents that penetrate and are absorbed through the skin. A person doesn't have to inhale paint to be exposed. They are exposed any time they have overspray on them." Painters need to be well protected, Miller said. He often speaks with owners and managers about the safety equipment provided to painters.

Binks face masks are good for painters that spray air-dried enamel paints, Miller said. However, these masks should not be worn by painters spraying urethane and isocyanate paints or coatings because air is only filtered through chemical cartridges that neutralize or absorb vapors.

The problem is a person cannot smell or detect isocyanate resins. The masks only provide temporary protection for painters spraying urethane and isocyanate coatings.

"After two to four hours, the isocyanate resins will pass through the chemical cartridges," Miller said. "Painters have no way to tell if a mask is functioning properly. Isocyanate is a bad actor. It is a suspected carcinogen."

Protecting Painters

When a painter smells solvents or if he has trouble breathing, he knows it is time to change the filter cartridges, Miller said. It is recommended that chemical filters are changed every four hours.

"It's not a situation to be taken lightly, especially if you use hardeners in air-dried enamels," Miller said.

Fresh-air-filter masks are highly recommended for painters that spray urethane paints and isocyanate hardeners, Miller said. To supply air to the mask, one type of fresh-air-filter mask has an air pump and the other has an air bottle.

Most of Miller's customers use air masks with a fresh-air pump, he said. The mask is available as a full-face or partial mask. Some are available with hoods.

"These masks look bulky, but they're really not," Miller said.

>From the front of the mask a breathing air hose connects to another air hose at belt level that supplies a spray gun, Miller said. This is a good mask to protect painters that spray isocyanate coatings.

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