Wear nitrile gloves!
Handling the cans and pouring paint leads to drips and spills. Therefore, gloves are absolutely necessary during mixing. Nitrile gloves offer the best protection against isocyanates in the hardeners. For the few minutes required for mixing, they also offer protection against many solvents. But to be sure of protection, the gloves should not be reused - solvents can leak through holes in the plastic that are much too small to see.
Local exhaust ventilation
When pouring and stirring the coatings, solvents evaporate into the surrounding air and can be inhaled. Mixing should always be done in a well ventilated area. Some shops use a local exhaust ventilation (LEV) system that captures the vapors with a hood, draws them away from the worker, and carries them through a duct to the outdoors. When using this type system, work as close to the hood as possible!
Other shops may use general ventilation in the mixing area. The air is often exhausted from the room with a wall or window fan. But, the air in the mixing area must be replaced with clean air fast enough to prevent the build up of harmful vapors. The fan should be located so that the contaminated air is drawn away from the worker. Cooling fans are not a good idea, since they just blow the fumes around, often into the general shop area. Ventilated mixing stations can be purchased, sometimes with a paint spray booth, or they can be custom made.
When lacking good ventilation, it is important to wear a fitted respirator with organic vapor cartridges to protect against organic vapors during all mixing tasks.
You probably already know that the paint you use is made from many hazardous chemicals. These chemicals, while necessary for the paint to be effective, can be harmful to your health if the proper precautions are not taken.
Use a booth or prep station!
The spraying of all the paint layers should always be done in a well ventilated spray booth. This protects both the painter and the paint job. Priming is usually done by autobody technicians rather than painters, and is often applied on the shop floor, but this can cause significant exposures to other technicians in the area. Many shops have invested in prep stations for both sanding and priming. [Prep stations are portable spray booths with ventilation and filtration of the exhaust air.]
The most effective paint booths are downdraft booths since they carry the paint away from the painter’s breathing zone. Semi-downdraft booths can also be effective, but the position of the painter is crucial. Whenever possible, the painter should orient himself so that he is upstream from the paint being sprayed, aiming the paint gun in the direction of the exhaust and away from himself (and toward the car, of course). Orientation is important for the cross draft booth as well. The painter should be as far as possible upstream of the surface he is painting.
What personal protective equipment should you wear in a booth?
All of these spray booths are very effective in preventing the solvents from contaminating the rest of the shop area, however, they do not sufficiently protect the painter. Therefore, the painter should:
- wear coveralls of tyvek or nylon and avoid exposing bare skin to the paint vapor or aerosol. If you don't have coveralls available, any long-sleeved shirt is fairly effective. Don't wear short sleeves.
- wear nitrile gloves if the paint contains isocyanates.
- most importantly, wear a respirator. It is generally recommended that a supplied air respirator be worn, however recent evidence shows that cartridge respirators with organic vapor cartridges, if properly fitted and worn, are also effective in preventing solvent and isocyanate inhalation.
After spraying a coating, the spray gun must be cleaned. This is usually done with solvents in the paint mixing area. Many states require that spray guns be cleaned in enclosed cleaners which recycle solvent. These cleaners reduce a painter’s solvent exposures and should be used. While cleaning guns, painters can inhale solvents from the coatings or the cleaning liquid, or can come in direct skin contact with solvents due to a splash or spill.
PPE and controls
- To prevent skin contact, the coveralls, eye protection, and gloves worn in the paint booth should be worn while cleaning the equipment.
- The mixing area should have good general ventilation to reduce the buildup of solvent vapors.
- A respirator, fitted with organic vapor cartridges, may also be worn.
- Keep the top of the gun washer closed when not adding or removing equipment from it.