FAQs, Part One

Recently, I traveled through Europe and South America, speaking to groups of signmakers about vinyl applications. Because my talks cover only the basics for applying films over flat surfaces, rivets and corrugations, I received several questions about special applications. Everyone who applies vinyl graphics periodically encounters vinyl installations on windows, drywall and compound curves. Here are a few answers to the most frequently asked questions.

Automotive pinstriping

Applying automotive pinstriping, which is usually thinner than an inch, requires a delicate touch, as opposed to installing truck graphics. Although many signmakers cut their striping on plotters, prespaced automotive striping and printed-graphics kits are available at automotive warehouse distributors, body shops and sign-supply distributors. Striping colors usually matches sign vinyl. To install pinstriping in a straight line, first remove 2 ft. of the release liner.

Tack one end of the striping to the car body, then stretch the remaining portion to the vehicle’s opposite end. As you work the stripe into position, remove the remaining liner paper. The ideal alignment usually requires repositioning the striping several times. The car’s body lines usually serve as the best reference points for alignment.

When the final positioning is determined, tack the stripe and keep the material taut – it can be slightly stretched. Overstretching the material, however, can bow the striping. Initially, pat the striping with a cloth folded into a pad, rather than squeegeeing the vinyl. At this point, a hard, stiff squeegee tends to stretch, buckle and distort the delicate pinstripe, which causes waves.

Automotive striping is usually masked with a clear application film. Always remove the application pinstriping tape after completing the application. Pinstriping usually isn’t wrapped inside the door jamb. Instead, the stripe is cut back 1/4 in. from a door’s edge. After placing the pinstriping, you can apply more pressure with either your thumb or a squeegee with a low-friction sleeve.

Some installers prefer to wrap wider vinyl around the door’s edges and inside the jamb. Be sure to clean any surface before applying the vinyl. Installing striping wider than an inch requires a different technique than pinstriping. After you tack the stripe into place, place the edge of your squeegee in the middle of the stripe to prevent it from moving up or down, which would produce a wavy stripe.

Squeegee strokes travel from the middle to the stripe’s outer edge. Always overlap your strokes. Never squeegee with a stroke parallel to the length of the stripe. Lengthwise strokes can cause the strip to stretch, buckle or wave. After squeegeeing, cut the stripe at the edge of the body panels. After removing the application tape, always re-squeegee the striping.

Curved surfaces

I’d like to advise you to never stretch any film, but this isn’t practical for vehicle applications. Vehicle surfaces usually have twists and turns, and the film must conform to these surfaces.

In many cases, it’s best to cut the vinyl around these areas. If you stretch vinyl, you can overstress it, which can cause it to fail. Vinyl is also like a rubber band. If you stretch it, it will try to stretch back to its original shape. When you’re stretching vinyl over a convex shape, into a concave surface or over compound curves, film manipulation is easier if you remove the application tape.

When confronted with indented areas in vans, don’t force vinyl into an indentation. Stretching the film, especially when it’s cold, can break it. Instead, first apply the vinyl into the indentation’s flat area. Then, very carefully press the film into the corners. If you need to stretch the film, apply heat to break the vinyl’s memory. Don’t overheat or overstretch the graphic, or you will damage it.

The success of applying a film to a curved surface depends on the appropriate film selection. Some films are more forgiving. Cast films, for example, stretch more easily than calendered films. An additional overlaminate layer makes a graphic less conformable. Polyester films (plastic), by their very nature, are very rigid and can’t be stretched over even simple curves. Select a film suited to the application, and then apply it without overstressing it. I prefer a cast film with a repositionable adhesive.

When you stretch a film, application temperature becomes more critical. At lower temperatures, films become brittle. If you don’t handle the film carefully, it could snap. If you’re installing graphics to a convex surface – an air dam on the top of a tractor – the vinyl may bunch up in the corners. You may need to cut excess material and overlap the film.

When installing graphics to air deflectors atop a tractor cab, you’ll usually straddle a ladder to the top of the tractor. When I worked on a project for a leasing company, the air deflectors would arrive separately from the power units. My friends at the leasing company called me when they arrived so I could install them on the ground. This is an unbelievable timesaver.

Key holes and bolts

Eventually, you will be asked to perform unreasonable applications. An easygoing, accommodating person may acquiesce to these requests, even if it’s wrong. Don’t do it. Either decline the job or ask the customer to sign a statement that releases you from any responsibility. Even then, if the application fails, your customer likely will blame you and refuse to pay his bill.

Don’t apply vinyl to door hinges, bolts, high-profile rivets, rubber gaskets and door locks. The film must be cut around – not applied to – these obstructions. Remove obstructing hardware and replace it after the vinyl application. This works better than trimming vinyl around an object. To cut vinyl around an obstruction, first cut an "x" over the bolt or keyhole. Then, using a squeegee or your thumb, tuck the vinyl in tightly around the obstruction. Finally, trim the vinyl with an X-acto® knife. Finally, apply more thumb pressure to ensure that the vinyl edge adheres well.

In some applications – high-profile rivets, rivets spaced too closely together and rivets on stainless-steel trailers, vinyl can’t be applied over the rivets. Such films as conspicuity-reflective films won’t conform to rivets. To cut vinyl film around rivet heads, |1927| (St. Paul, MN) has developed rivet-cutting tools that you should have. Check with your distributor, or examine the 3M tool catalog. When I did this many years ago, I ordered nearly everything.

The rivet-cutting tools include a thermal die that slips onto the end of a soldering gun. The heated tip melts the vinyl without having to apply any pressure. After you cut the film, remove the material over the rivet head.

The more traditional, rivet-cutting tool, which resembles a hole punch that cuts grommet holes, has a handle, which helps twist the tool to cut through the vinyl.

Roll-up doors

Before applying vinyl to roll-up doors, thoroughly clean the doors, especially the seams between the door panels. As you lift up on the door, the seam will open up, which allows you to wash and dry these edges. This prevents peeling.

After you apply the graphic and remove the application tape, double-cut the vinyl at each seam, that is, angle your knife at 45° and cut the film along the top edge of one panel. Along the bottom edge of the adjoining panel, make another cut at another 45° angle. To promote better adhesion, heat the seams with a heat gun or propane torch and then resqueegee all edges. Then, edge-seal all vinyl at these seams. Edge sealing isn’t an option; it’s a requirement.

Window-graphics film

Window graphics require special surface preparation. Before installing the graphics, thoroughly clean the window. First, wash the windows with a liquid detergent and water. Then, reclean the glass with isopropyl alcohol. Don’t use such glass cleaners as Windex® that contain silicones and ammonia, which can leave a residue that could hinder adhesion.

After washing carefully, inspect the windows. To clean windows speckled with dried paint, use a razor blade and re-wipe the windows with alcohol.

Keep your hands, which are dirt magnets, spotlessly clean when installing graphics to windows. When I install window graphics, I wash my hands in alcohol. It may not be healthy, but it works. Dirty hands transfer the dirt to the film’s adhesive side. Many customers notice and object.

If you’re applying film to glass in high humidity, and temperatures are below the dew point, moisture can condense on the surface, which could inhibit adhesion. Be patient and wait for warmer temperatures.

Window graphics should be applied dry. On a dry, window application, squeegee marks may appear on the film’s adhesive side after the graphic is installed. Assure your customer this is only temporary. The adhesive will flow out in four or five days, and the squeegee marks will disappear.

The same holds true for tiny bubbles underneath the vinyl. Time and temperature breathe these bubbles out of the film. Don’t puncture the little bubbles with a pin or knife. A worse problem is puncturing the film and creating a very noticeable hole through which light can shine.

To a certain extent, application fluid contaminates the adhesive. If a wet application is required, use appropriate squeegee pressure and overlap your strokes to force out any moisture underneath the vinyl. In cold climates, any remaining moisture could freeze and cause adhesion problems.

Usually, when you apply graphics in multiple panels, overlap the vinyl at least 1é4 in., where the panels form a seam. But don’t do this to perforated, window-graphic films, which comprise thousands of little holes that represent 40 to 50% of the total area. Perforated window-graphic films allow the printed image to be seen outside of a window. However, inside the window, the viewer still can see through it.

Because the film has so many little holes, there’s approximately half as much adhesive on the top, overlapping sheet. The bottom graphics panel has roughly half as much surface area to stick to.

Instead, butt the panels together. If you overlap the film, edge-lifting problems can also occur where the vinyl touches the edge of the window. Always trim 1/4 in. of the film away from the edge. To minimize edge lifting, you can always edge seal the graphic.

When a colleague and I inspected graphics panels with overlapping seams, we saw that most exhibited edge lift. When graphics start to peel at the edges, trim the peeled material and then edge seal the graphic.

Some vinyl companies recommend or require an overlaminate with their perforated window-graphics film. This precludes using application fluid, because fluid would be trapped inside each little hole. In the real world, very few people will use an overlaminate. Without an overlaminate, edges can lift and collect dirt.