Masking tape has been around for nearly 100 years, after being invented for the automotive industry in 1925 by 3M inventor Richard Drew. He noticed painters becoming frustrated when the heavy adhesive and butcher paper they were using pulled paint off of their freshly two-toned cars and developed a solution.
The overall goal of masking is simple: cover the areas that shouldn’t be painted. However, as all technicians know, this is easier said than done. The masking process is one of the most time consuming and painstaking operations in the repair process. It’s also one of the most thankless jobs because when done perfectly, no evidence of masking can be seen and all of the masking products are thrown away. As body shops today are pressed for cost reductions in all areas, some see masking as an area where they can save. This can be a costly mistake. Inadequate masking products can lift from the car, leave adhesive residue, tear multiple times during removal, and more. All of these deficiencies waste time, which is the most valuable asset a body shop has. Quality masking practices can help the masking process go faster and make repairs look better. Here are five recommendations for more efficient masking.
Keep weather conditions in mind when choosing masking materials Air conditioning for a whole shop can be extremely expensive, which is why many shops are at least partially exposed to weather conditions. Heat, cold and humidity all affect tapes in different manners, which is why a tape that works well in Minnesota may not perform as well in Florida, and vice versa.
Heat effectively lowers adhesion due to its “softening” effect on both backing and adhesive. This is why tapes can begin to lift as the job is brought into the booth. The higher temperature combined with additional air flow lift the tape off the substrate.
Cold stiffens the adhesive in tapes. This can affect the tape in both application and removal. A stiffer adhesive won’t adhere onto the substrate as easily, making it harder to create a bond. Upon removal, a stiffer adhesive will also be more apt to transfer. This is why it is common practice to remove adhesive soon after the bake cycle is completed.
High humidity means that there is more water vapor in the air, and most likely condensation on the panel surface. Tape adhesives are typically hydrophobic – meaning they do not want to interact with water. As the water is on the surface of the panel, tapes can have a harder time adhering.
Because of these factors, it may be wise for shops to change tapes according to weather, just as solvents are adjusted in the paint shop. For example, weather-related tape issues can be adjusted by using one tape for summer and another during the winter.
Clean all panels with solvent and waterborne cleaners prior to masking Vehicle panels are often littered with contaminants when they come into the shop. Even if a vehicle goes through a prewash before entering the shop, stray dust from sanded body filler or primer, technician fingerprints and other contaminants can get on the surface again. The only way to remove all contaminants is to clean with both water-based and solvent-based cleaners. Tape will stick to whatever is on the panel surface; so if there are still contaminants, an improper seal will be created. This can lead to overspray or dirt nibs – both of which cause extra time and labor to be corrected.
Keep the paint booth clean – especially when force-flashing basecoats The dirtier the paint booth, the more likely it is that dust and dirt will get into the base or clearcoats. Force-flashing coats also introduces more convection to the booth, possibly dislodging other contaminants from the booth or vehicle. This can create re-work and costs the shop time and money in the paint finishing department.
An easy way to avoid this is to use either a liquid booth coating or a protective booth wrap that can be applied to floors and walls. Both have their respective advantages and disadvantages. Liquid booth coatings are sprayable, which means they can usually be applied much faster than other booth protection solutions. However, these coatings are not able to hold much, if any, contaminants that can get into the clearcoat. This can cause dirt nibs and paint defects in the clearcoat if the coating is not properly washed and re-applied as often as needed.
Protective booth wraps are adhesive-coated with a non-woven backing. The non-woven backing is formulated to entrap dirt, dust and overspray – protecting the paint booth and keeping the trapped particles from being released during later jobs. This can reduce overall buffing time by decreasing the amount of paint defects. This solution costs more and takes longer to apply than a spray-on coating, as it needs to be hand-rolled onto the booth walls.
Tape directly to the plastic sheeting For years, materials such as newspaper, tarp and raw plastic sheeting were used to cover the car. While they all (for the most part) protected unpainted areas from overspray, they also introduced other contaminants to the paint job. Paint would also flake off the untreated sheeting and into the fresh paint job, causing re-work. This failure forced technicians to alter their processes to use 6- or 12-inch masking paper around the job in addition to plastic sheeting.
However, most premium automotive plastic sheeting offerings do not have this problem. These sheetings go through a chemical process called a corona treatment. The corona treatment changes the surface chemistry of raw plastic, allowing the paint to adhere to the plastic sheeting and not flake. Taping directly to the plastic sheeting can save time and material when compared to using the outdated combination of paper and sheeting.
Use specialty products to make jobs easier General-purpose masking tape is generally the cheapest type of tape and is quite versatile. However, shoe-horning general purpose tape for all areas can stress tape, lead to failures and take longer to apply than using specialty tapes. I outline two examples of overall specialty tapes below.
Washi-backed tapes feature ultra-thin, semi-transparent backing that is a great solution for:
* Creating sharp two-tones, especially with waterborne paints
* Conforming into textured surfaces such as claddings and bumper inserts.
* Masking over areas that need to be protected or cut out, such as with OEM labels.
Washi backing technology comes from Japan, and is a combination of typical cellulose fibers intertwined with polymeric fibers. This formulation allows an ultra-thin backing that still has the tensile strength needed for automotive masking. However, the thin backing cannot be stretched as far as typical general-purpose tapes.
Trim masking tapes feature a rigid plastic strip attached to paper or plastic backings. The rigid plastic strip allows techs to scuff, clean and paint behind the molding — allowing for better paint adhesion and hidden paint lines. Paper-backed offerings are hand-tearable, but can rip when trying to pull away very rigid moldings. Plastic-backed offerings have enough strength to pull all molding away from the surface and need to be cut to size.
With all that goes into a proper masking job, it’s easy to see why the best practice is to always match the right product with the situation. Rather than just thinking of masking tape and sheeting, think of these options as a “masking toolbox.” Doing so will help achieve a great finish, while saving time and money.
