Roll-on primers can offer a chance to reduce
cycle time and improve quality—believe it or not. Get Rolling
Check out the following paint
company Web sites or contact your local paint representative for more information.
Akzo Nobel (Sikkens)
www.akzonobelcarrefinishes.netBASFwww.basf.com DuPont Automotive Finishes
www.performancecoatings.dupont.comMartin Senour
www.martinsenour-autopaint.comMatrixwww.matrixsystem.comPPGwww.ppgrefinish.comSherwin-Williams
www.sherwin-automotive.comTranstarwww.tat-co.comValspar Refinish
www.valsparrefinish.comWhen the primer is placed has much to do with how fast the vehicle travels through the repair process. Primer must be applied to all repaired surfaces and any bare metal as one of the first steps in the prep process. Ideally, it should be done as soon after the metal is exposed to the atmosphere as possible. Vehicles waiting for the prep team to get to them are one bottleneck that can be addressed when attempting to improve shop efficiency. How the primer is applied may be an option to examine. Standard practice is to spray all refinish materials. This requires controlled environmental conditions, which usually means a spray booth, a prep deck or someone breaking the rules, if not the law, by spraying out in the shop! Alternatives to spraying do not exist for the final coats of finish, but for the first coats of primer, there are several alternatives. All of them are normally associated with house painting and will be frowned upon at first glance by most painters who have no experience with these techniques in the collision repair shop. But within certain guidelines, they may have merit.Cycle time
One common measure of efficiency is how long a vehicle is involved in the repair process. The term used is cycle time, usually defined as the time the damaged vehicle is dropped off at the collision facility until the customer drives away. Any time the vehicle is sitting waiting for someone to work on it is down time. Minimizing down time is the goal of any efficiency expert. If a way existed to get primer on the surface shortly after the repair was completed instead of waiting until the job could be moved to the paint shop, time could be saved. Using rollers or brushes is one option that has recently made a comeback. Some paint companies have recommended rolling on primers as an option for more than 10 years. Several are putting the idea back into the mix, and some companies are introducing the idea for the first time. Rolling?
The idea is simple enough; most liquid coatings can be sprayed, rolled or brushed. In almost all other industries, all of these options are used as appropriate. The automotive refinish industry is unique in that a very high-quality finish is required. Thus, the focus on high gloss and level finishes drives the use of spray equipment to place materials. However, the finish quality of the first primer coats is not very important as they will eventually be sanded smooth. In fact, “primer gun” is a term reserved for a paint gun that is not really good enough to spray color or clear out of but is good enough to get primer onto the surface. Is the leap from there to rolling the primer on all that far? Limitations of the technique
Not all primers should be rolled or brushed on. Paint coatings are made up of various materials that work together to determine the application process as well as the drying, curing and overall performance once in place. Specifically for the application process, solvents are added to adjust the viscosity for spraying and disperse the particles so the paint will coat evenly. Some of these solvents are evaporated during the time it takes the paint to travel from the spraygun head to the surface of the vehicle. Brushing or rolling does not readily cause this much evaporation. This means that either the primer will be very wet on the surface when rolled in place, or that the mixture should be adjusted. Some primers are specifically marketed for rolling, either as packaged or as mixed per vendor instructions. The conservative position is to use only those primers with manufacturer support for rolling. Using a primer without specific instructions for rolling is experimenting, and experiments sometimes fail. Remember, paint warranties only apply if all application instructions are followed.There are some limitations with this technique. Rolling a primer in place or using a brush will obviously introduce texture. With the proper technique, this can be minimized, and all of it can be sanded smooth. It is generally recommended for smaller areas. Rolling very large areas may result in a more uneven surface from trying to recoat with a roller after the first part coated has flashed. Some of the primers recommended for use with this technique may not be rated for use over bare metal. Advantages
There are several advantages to placing a primer on the surface mechanically instead of with a spraygun. Overspray is one major reason to consider it. Spraying procedures must be restricted to an area with a controlled atmosphere. This means a paint booth or prep station. The result is that primer operations have to wait for the vehicles to be moved to the paint area. The days of spraying primer in the body shop should be long gone. But a liquid applied with a brush or roller produces no overspray of mist or vapor, so there are few health or environmental concerns and very little masking needs to be done. The mechanical action of the roller greatly reduces surface tension within the primer. This, combined with the pressure of the roller on the vehicle surface, means primer does not bridge over pinholes, but flows into them and fills them up. Thus porous surfaces are particularly well suited for this technique. Minor pinholes in plastic bodywork will easily be filled, and those impossible-to-get-primed fiberglass panels are easily covered in a few quick passes. Rollers, trays, bags
As with any procedure, there is a learning curve to master when rolling primer on automotive surfaces. First is the choice of tools. The rollers suggested are smooth foam or small cell structure. They feature rounded ends and come in a few short sizes, generally 4 in. and 6 in. These can be purchased from some body shop supply companies and are packaged by some automotive paint companies specifically for use with their products. Do not try to use the very open cell or long nap fiber rollers. These may work well with house paint, but they will make a mess in this application. The rounded edges are also important as they leave a much less noticeable line than the square-edged foam rollers.Technique is also very important here. Practice will help perfect the process. Eliminating overspray does not mean there is not waste. All the primer in the roller and tray will be tossed out. Use a tray the width of the roller, perhaps with a plastic bag around it so the tray will not get paint in it. The costs are minimal for the rollers and trays. Rollers are not reusable without considerable cleanup, so some coordination or priming several jobs at once will reduce the expendable costs.Saturate the roller, but do not let it drip. Roll the primer smoothly over the area to be covered with a 50 percent to 75 percent overlap. Do not move too quickly or press too hard. A light touch will produce smooth applications. Continue rolling the primer until it starts to tack up. Stop as soon as the primer starts to stick to the roller. Any further rolling will produce a very rough surface. Flash time is the normal time between coats with sprayed applications. With rolling, the time between applications should be a little longer. The idea is to be certain that all the solvents have evaporated before applying the next coat. The end of the roller may be used with a stippling action to fill difficult pinholes or smooth out an edge from the rolling action. Film build
Obviously if this technique is to be of much use it needs to apply as much primer as a sprayed primer would. That is easily done with rollers. Two or three coats may be applied to achieve the same film build as the particular primer would if sprayed.
Why bother?So the question is, should a given shop consider this technique? If vehicles spend a considerable amount of time sitting in the shop before they are primed, or if pinholes are a regular issue, this may be a good process to have in the mix. Sprayed primers will not leave the prep toolbox, but adding rollers to that tool kit may make sense.
Check out the following paint
company Web sites or contact your local paint representative for more information.
Akzo Nobel (Sikkens)
www.akzonobelcarrefinishes.netBASFwww.basf.com DuPont Automotive Finishes
www.performancecoatings.dupont.comMartin Senour
www.martinsenour-autopaint.comMatrixwww.matrixsystem.comPPGwww.ppgrefinish.comSherwin-Williams
www.sherwin-automotive.comTranstarwww.tat-co.comValspar Refinish
www.valsparrefinish.comWhen the primer is placed has much to do with how fast the vehicle travels through the repair process. Primer must be applied to all repaired surfaces and any bare metal as one of the first steps in the prep process. Ideally, it should be done as soon after the metal is exposed to the atmosphere as possible. Vehicles waiting for the prep team to get to them are one bottleneck that can be addressed when attempting to improve shop efficiency. How the primer is applied may be an option to examine. Standard practice is to spray all refinish materials. This requires controlled environmental conditions, which usually means a spray booth, a prep deck or someone breaking the rules, if not the law, by spraying out in the shop! Alternatives to spraying do not exist for the final coats of finish, but for the first coats of primer, there are several alternatives. All of them are normally associated with house painting and will be frowned upon at first glance by most painters who have no experience with these techniques in the collision repair shop. But within certain guidelines, they may have merit.Cycle time
One common measure of efficiency is how long a vehicle is involved in the repair process. The term used is cycle time, usually defined as the time the damaged vehicle is dropped off at the collision facility until the customer drives away. Any time the vehicle is sitting waiting for someone to work on it is down time. Minimizing down time is the goal of any efficiency expert. If a way existed to get primer on the surface shortly after the repair was completed instead of waiting until the job could be moved to the paint shop, time could be saved. Using rollers or brushes is one option that has recently made a comeback. Some paint companies have recommended rolling on primers as an option for more than 10 years. Several are putting the idea back into the mix, and some companies are introducing the idea for the first time. Rolling?
The idea is simple enough; most liquid coatings can be sprayed, rolled or brushed. In almost all other industries, all of these options are used as appropriate. The automotive refinish industry is unique in that a very high-quality finish is required. Thus, the focus on high gloss and level finishes drives the use of spray equipment to place materials. However, the finish quality of the first primer coats is not very important as they will eventually be sanded smooth. In fact, “primer gun” is a term reserved for a paint gun that is not really good enough to spray color or clear out of but is good enough to get primer onto the surface. Is the leap from there to rolling the primer on all that far? Limitations of the technique
Not all primers should be rolled or brushed on. Paint coatings are made up of various materials that work together to determine the application process as well as the drying, curing and overall performance once in place. Specifically for the application process, solvents are added to adjust the viscosity for spraying and disperse the particles so the paint will coat evenly. Some of these solvents are evaporated during the time it takes the paint to travel from the spraygun head to the surface of the vehicle. Brushing or rolling does not readily cause this much evaporation. This means that either the primer will be very wet on the surface when rolled in place, or that the mixture should be adjusted. Some primers are specifically marketed for rolling, either as packaged or as mixed per vendor instructions. The conservative position is to use only those primers with manufacturer support for rolling. Using a primer without specific instructions for rolling is experimenting, and experiments sometimes fail. Remember, paint warranties only apply if all application instructions are followed.There are some limitations with this technique. Rolling a primer in place or using a brush will obviously introduce texture. With the proper technique, this can be minimized, and all of it can be sanded smooth. It is generally recommended for smaller areas. Rolling very large areas may result in a more uneven surface from trying to recoat with a roller after the first part coated has flashed. Some of the primers recommended for use with this technique may not be rated for use over bare metal. Advantages
There are several advantages to placing a primer on the surface mechanically instead of with a spraygun. Overspray is one major reason to consider it. Spraying procedures must be restricted to an area with a controlled atmosphere. This means a paint booth or prep station. The result is that primer operations have to wait for the vehicles to be moved to the paint area. The days of spraying primer in the body shop should be long gone. But a liquid applied with a brush or roller produces no overspray of mist or vapor, so there are few health or environmental concerns and very little masking needs to be done. The mechanical action of the roller greatly reduces surface tension within the primer. This, combined with the pressure of the roller on the vehicle surface, means primer does not bridge over pinholes, but flows into them and fills them up. Thus porous surfaces are particularly well suited for this technique. Minor pinholes in plastic bodywork will easily be filled, and those impossible-to-get-primed fiberglass panels are easily covered in a few quick passes. Rollers, trays, bags
As with any procedure, there is a learning curve to master when rolling primer on automotive surfaces. First is the choice of tools. The rollers suggested are smooth foam or small cell structure. They feature rounded ends and come in a few short sizes, generally 4 in. and 6 in. These can be purchased from some body shop supply companies and are packaged by some automotive paint companies specifically for use with their products. Do not try to use the very open cell or long nap fiber rollers. These may work well with house paint, but they will make a mess in this application. The rounded edges are also important as they leave a much less noticeable line than the square-edged foam rollers.Technique is also very important here. Practice will help perfect the process. Eliminating overspray does not mean there is not waste. All the primer in the roller and tray will be tossed out. Use a tray the width of the roller, perhaps with a plastic bag around it so the tray will not get paint in it. The costs are minimal for the rollers and trays. Rollers are not reusable without considerable cleanup, so some coordination or priming several jobs at once will reduce the expendable costs.Saturate the roller, but do not let it drip. Roll the primer smoothly over the area to be covered with a 50 percent to 75 percent overlap. Do not move too quickly or press too hard. A light touch will produce smooth applications. Continue rolling the primer until it starts to tack up. Stop as soon as the primer starts to stick to the roller. Any further rolling will produce a very rough surface. Flash time is the normal time between coats with sprayed applications. With rolling, the time between applications should be a little longer. The idea is to be certain that all the solvents have evaporated before applying the next coat. The end of the roller may be used with a stippling action to fill difficult pinholes or smooth out an edge from the rolling action. Film build
Obviously if this technique is to be of much use it needs to apply as much primer as a sprayed primer would. That is easily done with rollers. Two or three coats may be applied to achieve the same film build as the particular primer would if sprayed.
Why bother?So the question is, should a given shop consider this technique? If vehicles spend a considerable amount of time sitting in the shop before they are primed, or if pinholes are a regular issue, this may be a good process to have in the mix. Sprayed primers will not leave the prep toolbox, but adding rollers to that tool kit may make sense.
About the Author
Charles Wilhite
Charles Wilhite, owner of Gamut Services, provides training and consulting to the automotive colli-sion industry. He is an active I-CAR instructor, I-CAR Advantage contributor and an ASE-certified Master Collision Repair/Refinish Technician with more than 25 years in the trade. He also teaches composite construction and repair in the aviation industry.
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