Putting a Decal On in Cold Weather

If a decal has been waiting in your glove box since fall, winter may be when you finally want it on the car. Winter is also the season the film makers warn about most. Cold changes the vinyl, it changes the adhesive, and it changes the glass you are pressing them onto.

None of that means a winter decal is doomed. It means the steps in our guide to applying a vinyl decal matter more, and a few of them change.

What cold does to vinyl

3M's dry application bulletin describes the problem in three parts. Below the minimum application temperature, films become stiff and brittle. The adhesive cannot bond adequately with the surface. And air may be trapped under the film and show up as bubbles.

On a die-cut decal there is no clear border around the design, so every edge of every letter and every shape is an edge of the film. 3M ties edge trouble to the adhesive itself: contamination on the adhesive edges, it says, may cause the edges of the film to lift after application. Add a bond that cold has already weakened, and the edges are the place to watch.

There is a fourth problem, and it has nothing to do with the vinyl. 3M says the surface must be warmer than the dew point, or moisture condenses on it. On a cold, damp morning that moisture can settle on the glass before you notice it, and the decal goes down onto a film of water instead of clean glass.

The numbers in the bulletins

Film makers print an application temperature for each of their films. 3M's rule is that the air, the film and the surface all have to be inside the range in that film's own product bulletin. No single number covers every vinyl, but the documents below show the kind of range you are working with.

Each figure belongs to the film named. Conversions marked "about" are ours.

Two things stand out. The minimums sit in the high 40s and low 50s Fahrenheit, well above freezing. And the conditions ORAFOL prefers are room temperature, not merely a mild day. Our advice is simple: work at the warm end of these ranges, never at the bottom edge.

Warm the glass, not just the room

3M's rule names the surface as well as the air. A car that spent the night outside keeps cold glass for a while after you pull it into a heated garage, and the decal needs the glass itself to be in range, not only the air around your hands.

The same goes for the decal. A package that rode home in a cold trunk is cold film, and 3M counts the film's own temperature in its rule. Bring it inside and let it sit at room temperature before you open it.

Clean the glass the way you would in any season: detergent and lukewarm water, a thorough dry with lint-free towels, then isopropyl alcohol, wiped off before it evaporates. In winter, do that last wipe right before the decal goes on. 3M asks for that in every season because dust settles fast, and in cold air the dew point gives you one more reason not to let clean glass sit.

Winter adds one more trap to the cleaning. A car that has just come out of an automatic wash looks its cleanest, but 3M warns that the chemicals used in some automated washing equipment may interfere with adhesion, and that some window cleaners contain waxes. Before the alcohol, run 3M's water test: put a few drops of water on several parts of the glass. If they bead, a wax or coating is still there, and it has to come off with another detergent wash before the decal will bond.

• Glass, air and decal all inside the film's printed range, and closer to its warm end than its cold one.
• Glass washed with detergent and lukewarm water, dried with lint-free towels.
• No beading when you drop water on the glass.
• A last wipe of isopropyl alcohol, dried before it evaporates, right before you start.
• Masking tape and a plastic squeegee within reach, and no plan to wash the car for two days.

Dry application, every time

If you have seen installers float a decal on soapy water, leave that method for summer. 3M lists graphics that will face freezing conditions within several days of application among the cases where it typically recommends dry application only, and vehicles are on the same list. ORAFOL limits wet application to warm weather, at 18°C (about 64°F) or more.

The reasoning in the bulletins is short. Any liquid left under the graphic keeps it from adhering properly, 3M says, and its surface bulletin adds that moisture trapped beneath a graphic can make it fail early.

So use the hinge method from our application guide. Hold the decal in place with masking tape, put it down one half at a time, and squeegee from the hinge outward with firm, overlapping strokes. Then peel the transfer tape slowly, folded back flat on itself, and squeegee the whole decal again. 3M prints that last step in capitals, since pulling off the tape can loosen the edges.

The first day and the first weeks

Getting the decal down is half the job. ORAFOL asks you to avoid a significant drop in temperature in the first 24 hours after application. If you have the choice, let the car spend that first night in the warm garage rather than driving straight back out into the cold.

3M is blunter about winter. A graphic applied near the minimum application temperature and then put immediately into service in winter weather may not develop ultimate adhesion, it says. In a driveway, that means a decal applied at the bottom of its range on a January afternoon may never hold as firmly as the same decal applied in May.

Washing waits too. Avery Dennison asks owners of its films not to wash them in the first 48 hours, and our decal care and removal guide has the pressure-washer limits for the weeks after that.

When to wait for spring

Sometimes the right call is to leave the decal in a drawer. If you have no warm space to work in, if the glass will not come up to temperature, or if water still beads on the glass after you clean it, the bulletins all point the same way: the adhesive will not bond the way it should.

Cold also makes removal harder, which is worth knowing before you commit. 3M says film becomes brittle below 10°C (about 50°F) and breaks into small pieces as you pull it, so a decal that went on badly in January is also a decal that comes off badly in January. Getting it right the first time, on a warmer day, saves you that second job.

Waiting a few weeks costs you nothing but the wait. If the decal is a long banner for the rear window, use the time to read where a decal can go on a car, since California, Texas, Florida and New York all attach conditions to the rear window. And if you have not chosen one yet, our car culture decals and rear window banners are a good place to start the list.