Masking anything always has two components: the products used to cover the area and the labor to install and remove them. No clearer example illustrates the significance of the labor component than masking with discarded newspapers. The cost of the paper is zero, and only the masking tape must be purchased. However, the cost of labor to place a strip of tape along the edge of each sheet of newsprint is enormous. No matter how cheaply you intend to cover cars against paint overspray, labor time remains the most expensive component. That’s why, to be financially ahead, you should always try to attach and remove masking materials in the least amount of time.
The Inter-Industry Conference on Auto Collision Repair (I-CAR) Uniform Procedures for Collision Repair (UPCR) are now available at no charge on I-CAR’s Web site at (www.i-car.com). Visit the site and you can download tons of information for free. One area they address is masking. They name the materials used and the areas to cover when masking for automotive refinishing, identifying 10 masking materials: masking paper, masking tape, plastic masking, wheel covers, liquid masking, heavy-duty masking, fine-line tape, molding lift tape, foam tape and back-masking tape.
Let’s take a look at each and see what makes them work.
Masking paper is made like any other paper. At an integrated papermill, timber goes in one end and paper comes out the other. During the process, the trees are ground into wood pulp, which is then cooked in water and sprayed onto a screen. The water is then drawn off, leaving a mat of tiny fibers. The mat is run between two heavy rollers, like a chamois wringer, to squeeze out even more moisture. This compressed, matted vegetable substance in thin, flexible sheet form is called paper.
Several additional bells and whistles in the process can produce paper of varying qualities. Newspaper, for example, resides at the bottom of the quality heap, since it’s intended to be read once and discarded. Without the addition of various neutralizing acids, the contaminants in the wood pulp turn the newspaper brown over time.
The paper used in hardcover books is treated to resist the browning that comes with age. Better-quality paper gets polished into a slick surface by rolling against other metal rollers at high speed on a calender machine. It can also be shaved with a thin blade, placed against the roller, as the paper spins by. The goal of the blade and roller treatment is to remove the tiny excess fibers that stick up.
Regular (often green) automotive masking paper is treated to resist solvent penetration from thinners in automotive paints. Each time the masking paper is soaked with solvent, drying as the solvents flash back into the air, more and more tiny fibers come loose from the mat. These fibers can drift and settle into fresh paint and ruin the finish just as harshly as floor dirt can.
One solution to this is to double mask, which means putting one layer of paper over another. After the undercoats or basecoats are applied, the first layer of paper is removed. Then the final clearcoats are applied.
Premium-grade masking papers have two advantages over the regular-grade variety. First, they’re more thoroughly shaved by the Doctor blade or by a hot wire strung over the paper as it spins off the reel. Removal of the highest number of protruding fibers allows the premium paper to withstand more soak/dry cycles before any fibers come loose. After enough soak/dry cycles, any type of paper will start to shed; the premium-shaved papers give the painter a couple of free rounds first.
Premium masking papers are also coated on the backside to prevent any solvent from soaking through. Newsprint or butcher paper lets harsh solvents pass right through, like a sponge, and the areas underneath are subjected to a bath. Coating the paper with wax or plastic makes it effectively solvent-proof, keeping the masked areas clean and dry.
I remember when the first premium-grade masking papers were introduced. The demo included rolling a piece of new paper into the shape of a funnel, twisting the bottom shut and pouring lacquer thinner into it. With regular green paper, the solvent would quickly soak through and run down the painter’s hand. With coated paper, the thinner remained inside the funnel and the painter’s hand stayed dry.
Masking tape is made flexible by bending the paper into tiny pleats. The crepe paper streamers your mother used to decorate the basement for your fifth birthday party were made the same way. In order for paper to turn corners, the crepe process is necessary. To illustrate, tear off two strips of notebook paper 6 or 8 inches long. When you try to bend the first, it tears. Take the second and fold it into little pleats, like in an accordion. This strip can now be bent into a slight curve without tearing. Regular automotive masking tape is crepe paper treated to resist solvents. The downside is that the edge of the tape leaves a fuzzy border when the paint creeps under the tiny pleats.
Hardware store masking tape, also crepe, is different from automotive-grade tape. One difference is dead stretch. If the paper is crepe with deep pleats, it will turn tight curves but tends to extend as it’s pulled. Automotive masking tape hits a nice balance of tight turns with little stretching. Also at issue is the treatment the paper receives to resist solvents. We use much stronger solvents than what’s found in typical latex house paint, and any tape must prevent solvent bleed-through. Ours has been coated, starched and impregnated to repel strong solvents.
No tape of any kind will stick well if the surface isn’t clean. Use wax and grease remover or other appropriate cleaners to remove everything between the tape and the vehicle, or you’ll be cleaning overspray off tomorrow.
One masking tape element that’s become more prominent in the last few years is the adhesive that makes the product stick to the car. It was always important that the adhesive be sticky enough to attach to difficult surfaces, like rubber weather-strip, but still release cleanly days later when the job was unmasked. As most painters know, leaving a car masked with inexpensive tape sitting outside in the hot sun for a few days leads to horrible problems when the tape is finally removed. The tape shreads, and the adhesive sticks to the car. Now that many more shops have heated spraybooths, the high temperature adhesive transfer problem has become much more important.
Part of the problem is the human nature of guys. We just want to open whatever it is wide open, full speed and get going. If you show the typical male a temperature gauge with a range from 120 degrees F to 180 degree F (like the settings for a force-cure oven), most will immediately spin the dial all the way up. If a little heat is good, more heat is better! However, the hotter it gets, the harder it is to keep the adhesive on the back of the tape. Today’s premium crepe masking tapes do a great job keeping their adhesive. One solution to this transfer problem is to use adhesive that’s clear and not easily seen if it remains on the car after unmasking.
In my experience, plastic masking film is the most prevalent method used to mask cars. Typically, 12 feet wide by 400 feet long is an inexpensive and relatively quick method to cover large areas. Several variations exist to suit special circumstances. Roll width has gotten wider, first to 14 feet, then to 16 feet wide — enough to reach the ground when draped over even the tallest vans or truck cabs.
Plastic film is available in several thicknesses. Measured in mils (thousandths of an inch), the thicker films are more durable and will withstand more tugging and abrasion than less expensive thin films. Also, some films are treated to remove static charge, while some are treated to increase it. Plastic sheeting with substantial static charge clings to the car and tends not to be blown away from the surface by the blast of air from the spray gun. However, carefully pinning down the edges of the sheeting with magnets or tape is necessary in every case.
Plastic covers or bags are my favorite method to mask cars. While they’re more expensive than a similar length of plain sheeting, they’re much easier for one technician to install. In many shops, the painter receives some help from another tech to quickly cut and install the 12-foot-wide sheeting on the car. If the average door rate is $34 per hour, then each minute is worth 57 cents. Two techs for three minutes equal $3.42 in labor costs to install sheeting. Bags are more expensive per foot than sheeting, but because they have a heat seam (at 21 feet or 25 feet), a single tech can place the bag around one end of the car and pull against it, covering the vehicle by himself.
I believe the total material/labor costs are less for bags. Not only that, but the look of the bag sends a good message to customers who see all the cars in the shop bagged up and protected from damage or overspray. With any kind of plastic masking, using plenty of razor blade cutters and magnetic hold-down strips make the job go faster and protect the car better.
Wheel covers come in several styles, and each offer an advantage. One of the oldest methods to mask tires and wheels is to wet the masking paper in the sanding bucket water and tuck the paper securely around the tire. When the paper dries, the dirt on the tire and wheel is trapped inside the cocoon of paper. Today, the most prevalent method uses cloth covers with a wire hoop sewn inside. These maskers are quickly installed and removed from the vehicle. But they’re not a lifetime investment. When your wheel maskers can stand up by themselves, it’s time for a new set.
If you don’t replace ancient maskers, the dried overspray will shed more dirt into the paint than it will restrain on the tire. One way to beat that is to use disposable plastic wheel maskers, which are designed for a single use before discarding. Whichever method you use, remember that any overspray in the wheel wells will send an extremely negative message to the customer when he picks up the car. If you’ve left paint or primer showing on the suspension or the tailpipe, the customer will suspect the entire repair is deficient.
Liquid masking comes in two styles. One is made from a glycerin or soap film, and the other has an alcohol base. Both types are removed from the car with water and do a great job trapping the dirt and dust under them.
With either style, you still need to outline mask with 12-inch paper around the edges of the repair. This isn’t surprising if you think about it. It’s asking a lot for any sprayed-on film to withstand a direct blast from a loaded paint gun. Both styles also offer an advantage shared by plastic film: You can see through the windshield as you move the car into and out of the booth. It is the rare painter who hasn’t scraped the car on something as he peered around the opaquely masked glass and through the partially open driver-side door. It’s hard to see the other side of the car that way.
In the early days of liquid masking, you needed special spray guns and large drums of material before your shop could give it a try. Aren’t you curious to see if spray-on would offer your shop any advantage? These days, most spray-on liquids will shoot through regular spray guns and can be purchased in quantities as small as 1-quart. Perhaps you should try it on two or three cars first. A good place to start is with a vehicle that has parts difficult to cover with paper or film. One example is the pickup truck jacked up on tall shocks with snazzy rubber dust covers over them. The labor time required to twist paper around each shock would buy several gallons of liquid mask.
Another benefit is that it’s easy to apply another coat after all the bodywork and undercoats are on, but before starting on the base/clear coats. Sealing down all the previous sanding dust and overspray keeps the job much cleaner. Leaving the spray-on in place until after the car’s final sanding and polishing keeps the compound spatter off the doorjambs as well. Total labor time includes prep, paint and detail. Choosing a masking method that works well for each stage keeps everyone’s time down.
Heavy-duty masking is generally designed to withstand abrasion or exposure to the elements. Examples of abrasion are the whirling 9-inch grinder, the sandblaster used to strip to the substrate or the sparks from welding. Weather elements in question might be the sun, wind and rain (or dew) that attack any vehicle left outside the shop overnight. Any extra expense to double mask or use thick and costly masking materials is always much cheaper than replacing previously undamaged parts that get ruined as the repair progresses. A stitch in time really does save nine (dollars, that is).
Fine Line Tape
Fine-line masking tape is made from plastic, not paper. As such, it already does a pretty good job resisting solvent penetration. These tapes were invented to provide the nice sharp line that separates a two-tone paint job. The pleats in paper tape leave an uneven edge; plastic tapes do not. Since the tapes were designed for two-tone (the first color is pretty fresh when masked), they generally don’t have as much adhesive on the back as paper tapes. To make the plastic film thin enough to turn corners adequately means that it will also stretch if you pull too tightly when applying it. Be careful to pull it off the roll gently.
A related type of plastic tape is the conformable version. Like regular fine-line tapes, it leaves a sharp line, but the plastic film in this tape will follow surface contours better than either regular plastic tape or paper types. Originally invented to mask rivet heads protruding from semitrailers, it’s just the ticket for any intricate masking jobs, like flames or fancy pinstripes.
Molding Lift Tape
Molding lift cord isn’t necessary in your average Rolls Royce restoration shop. Those shops always remove all the glass in the car. Then there are no rubber gasket edges or flush-mounted plastic trim edges to worry about. The used-car weasel down the street doesn’t use the cord, either, because his customers don’t mind when the paint builds up on the masked edge of the gaskets and moldings.
If, however, you’re doing late-model collision repair and want your present customers to return when they need more body work, you’d do well to lift the flush-mount edges away from the car to minimize the re-painted effect.
Lifting cord comes in a variety of shapes that can squeeze under even the smallest, tightest trim. Stiff and oddly shaped lift cords cost more than the three sizes of plastic clothesline stuff. Once again, the labor component makes the more expensive systems with special cords and several different installation tools well worth the money, since time is saved lifting the edges out of the way.
Foam and Back-Masking Tape
Round foam tape is a clever solution to a long-standing problem. Originally called door aperture tape, it works well anywhere an opening panel meets another. The gap between the decklid and the quarter panel needs to be quickly sealed, too. Not only is this an easy way to stop overspray intrusion, it also works great for a soft-rolled edge. Also called back-masking, the notion is to soften the edge where the new paint meets the old. Originally, painters applied 2-inch tape loosely and peeled one edge back up over the other, leaving an uneven front edge.
Behind the Mask
Choosing the style or brand of masking product that’s best for your techs remains a tough job. If you haven’t changed the way your shop masks cars lately, you should try some other methods soon. Cars have changed, paint has changed and spray guns have changed. A few days fooling around with different ways to mask may pay off big for your current refinish system.
I suggest you try several brands of whichever methods appeal to you and buy them in small sizes. Buying 25 plastic wheel maskers is more expensive per bag than buying a big box of 100, but if you don’t particularly like plastic wheel maskers, it’s much easier to toss out the last 10 and try something else. If you haven’t tried spray-on masks for a few years, buy a gallon of both the wet and dry varieties and see what suits you. Unlike paint systems where chemical compatibility demands you stay within a brand, here you can mix up all your masking supplies until you get the best job.
What’s the best job? My definition would be one with as few flaws on the car as possible. The minutes you allow to tack down all the loose paper edges prior to spraying will save you 10 times the work spent trying to remove the overspray before delivery. Try different methods, buy the best and spend as little time as possible covering and uncovering the vehicle. After all, you have more important things to do.
Writer Mark Clark, owner of Professional PBE Systems in Waterloo, Iowa, is a well-known industry speaker and consultant. He’s been a contributing editor to BodyShop Business since 1988.
The photos appearing in this article were provided by BodyShop Business contributing editor Mike Regan.