Creating garment graphics from heat applied thermal film, aka “Heat Transfer vinyl*”, is a pretty simple process, but it also has its quirks. Making the transition from cutting standard vinyl graphics for doors and windows can be a bit confusing at first. If your first experience with vinyl cutters is with T-shirt graphics, the learning curve is a little steeper. To help you clear those hurdles more quickly, we offer this basic thermal transfer troubleshooting guide.
Here are simple answers to problems in three basic categories: problems with adhesion, problems with color migration, and problems with cutting or weeding. If you're dealing with one of these problems, you may think your t-shirt transfer material is defective. It's probably not. Before you call customer service and ask for a replacement, try the tips below. You'll probably gain some valuable insight about how heat transfer film works and save yourself some time in the process. Here's your T-shirt vinyl troubleshooting FAQ.
Why is my Heat Transfer Vinyl Not Sticking?
The most common complaint we receive is that a film won’t stick to a garment. This can be further broken down into two categories; initial adhesion, and final adhesion.
Initial Adhesion: Problems with initial adhesion occur when the process of removing the liner lifts the newly pressed letters. Generally when customers experience this problem, they assume the film is defective. This is usually the least likely reason for the problem. Here's where to start. This can be caused by insufficient pressure, temperature, or time.
Time: Some heat transfer films need a few seconds to cool before you remove the liner. Try a warm or cold peel first.
Temperature: If a warm peel method doesn’t work, check to make sure you are using the recommended time and temperature settings. Then check to make sure your heat press' temperature display isn't lying to you. This cannot be overstated. Most heat presses do not show the actual temperature of the heat platen. Entry level imported heat presses are notoriously inaccurate. Even otherwise fine quality made-in America presses can be off by as much as 25°. If you think you're pressing your EasyWeed transfer at 305°F, and the film is actually only being heated to 280°, it probably won't stick.
You could just begin raising the set temperature until it works, but you'll be guessing and wasting a lot of time. The best solution to this problem is to find out the actual temperature output of the heating element. Point & shoot IR thermometers don't work well for this because they don't give accurate readings on aluminum. Use a Geo Knight IR thermometer kit to confirm the actual temperature of the platen. Yes, it costs $85.00 and that's a pretty penny. But if you're making t-shirt transfers as a business, consider this a necessary investment in your success. Use the IR kit to find out the actual temperature of the heat press. If your press can be calibrated, use that information to calibrate the temperature display so that it's correct. If your press' display can't be calibrated, you can at least adjust the dial to reach the desired temperature.
Pressure: If the temperature is correct, and you're giving it enough time to cool and it's still not sticking, adjust the pressure. It's called a heat 'press' for a reason. All heat transfer films require a certain amount of pressure to allow the adhesive to fully bond with the fabric. Some require more than others. If there's no resistance when you try to fully close the press, you're not using enough pressure.
Coatings: The other probable reason for initial adhesion failure is the presence of a coating on the fabric. These can come in the form of a moisture repellent or antimicrobial coating. Moisture repellent coatings are normally found on products like tents and nylon rain coats. Coatings on Nylon can often be removed by pre-heating the fabric with a sheet of silicone paper or Kraft paper to absorb and remove the added chemical. Antimicrobial coatings are normally found on performance apparel. It's added to repel bacteria and odor, but may also repel your heat transfer film. As the activewear market becomes more popular and lucrative, the use of these coatings is becoming more common, as are the associated HTV failures. Click here for more information.
Why Did My Heat Transfer Vinyl Fall Off?
Mixed Layers: When an appliqué sticks initially and comes off later, it may be because of improper layering. When applying one layer of T-shirt film upon another, always use similar products. Warm peel films can be applied in layers on other warm peel films. Likewise, you can usually layer or overlap cold peel PU films one with another. But mixing hot and cold peel films is a recipe for failure and frustration. And if you're layering a metallic film like Chemica Galaxy with a standard PU product like Chemica Hotmark, the metallic layer must be on top. Here's a link to the Siser layering guide.
Incompatible Fabric: Another probable reason for initial adhesion failure is a simple fabric mismatch. You put the right film on the wrong fabric, or vice versa. Check the film’s specifications and make sure you’ve chosen material that’s suitable for your garment. Using a film designed for nylon and leather on all of your shirts may seem like an economical choice, but these films are prone to failure on cotton, polyester and blended garments, especially when washed in hot water. If you want to play it safe, choose a universal film like Logical Color WarmPEEL Universal or Chemica HotMark Revolution. These are advanced heat transfer films that can successfully be applied on cotton, polyester, blends, and Nylon. Just make sure you read the directions and set the time, temperature and pressure accordingly.
Improper Laundering: The other possible cause for heat transfer failure is laundering. This one is the most vexing because it’s the only one outside your control. All you can do is advise customers to treat their decorated garments as delicates and wash them accordingly. The best method is to wash them inside-out in cold water. Turning the garment inside-out protects the applied film from abrasion caused by contact with zippers and other elements in the chaotic mashup inside the washing machine. Wash temperature is also important. Some heat transfer films can stand higher temps, but the cooler the better.
Why Does My White HTV Look Pink?
Another common complaint in this field is color migration, which occurs when the dyes in the garment transfer to the applied film. This most often occurs when people apply white or brightly colored graphics to dark polyester or cheap cotton shirts. The white turns slightly or markedly gray. The black dye with which the shirt was made has been activated by the heat and migrated into the film. There are three ways to tackle this one.
Change your shirt. This problem most commonly occurs in dyed or sublimated polyester garments. If you have a shirt that’s been decorated by dye sublimation, the press may reactivate the dye and sublimate your film. The other cause is the influx of low-quality imported cotton shirts that are made with thermal reactive dyes. A garment upgrade to a higher quality shirt, such as a Hanes BeefyT will fix this. If you can’t change clothes you can change the film. If you're dealing with a polyester garment, there are two approaches.
Lower Temperature Film: Choosing a film that can be successfully applied at lower temperatures is a great solution. Sublimation occurs at or near 400°F. If you can use a film that can be applied to polyester at less than 300°F, you can apply your cool custom graphic without activating the dyes in the fabric. The aforementioned universal films, WarmPEEL Universal and HotMark Revolution both have low temperature settings suitable for safely decorating sublimated polyester.
Thicker Film with Dye Blockers: The other approach is to choose a thicker film that includes an extra layer between the adhesive and face film that blocks dye migration. These are typically more expensive and, because they're harder to manufacture, come in a smaller color palette. And the extra layer sacrifices some softness. If you choose this route, ChemicaHotmark SIR (Sublimation Ink Resistant) may be just the right film for you.
Why Can't I Cut it?
Most heat transfer film is very thin and soft and pretty easy to plot. If you do have trouble cutting one of these products, the issue is most likely one of four things; improper film loading, an extra liner, incorrect blade, or excessive blade wear.
Film loading. Most CAD T-shirt films are shipped with the liner facing outward so that, when you load it on a standard roll fed plotter, you are cutting the face film from the bottom. If you load it incorrectly, you will be cutting the liner, which may be much thicker and tougher. If reasonable amounts of cutting force aren’t working, and it’s your first time with a particular film, flip it over and do a test cut.
Extra liners. Some specialty films are shipped with an extra liner designed to protect the face film during shipping and storage. This layer should be removed—carefully—before you attempt to plot your graphic. Only uncover an area large enough for you to cut your desired image so that the protective liner stays in place on the remainder of the roll. And if you're cutting it off, don't cut too deeply or you'll mar the face film.
Incorrect Blade. Most T-shirt vinyl can be cut easily with a standard issue 45° plotter blade. However, some are thicker or denser than average and require a 60° blade, also known as a “flock blade”. Coincidentally, flock is one of the things that requires this extra blade depth. Glitter-flake films like Siser Glitter or Logical Color Glitter Soft also require a 60° plotter blade. The glass beads in reflective heat transfer films like Logical Color Scotchlite Reflective and Siser Reflectall also do a number on standard plotter blades. These specialty films also require a 60° blade.
Blade wear. If you’ve got the film loaded correctly, there isn’t an extra liner, and you’re using the right kind of blade, and you still can’t cut the material, it may be simply because your blade is damaged or worn out. Plotter blades are consumables and sooner or later, their useful lives are consumed. The more you use soft Polyurethane films like HotMark 70 and Easy Weed, the longer your blades will last. The more you use denser materials like Reflex and Glitter, the shorter your blade life will be. Your mileage may vary.
Why is This Stuff So Hard to Weed?
Weeding problems are really cutting problems in disguise. If you are having trouble weeding a graphic cleanly, it’s most likely because you've cut into or through the face film, but not the adhesive. You can also cause weeding problems by going to the other extreme and cutting too deeply, if you're using a film on a paper liner. Scoring too deeply cuts the face film, adhesive, and release liner. When you try to weed it, the liner comes up with the rest and clings to the film, which kind of defeats the purpose. To reduce the chances of discovering one of these costly errors after having cut a full page of graphics, always, always, always, perform a test cut first. Then weed it on the plotter before sending your job.
The standard test cut from a Q Series or Graphtec is a triangle in a square. You should be able to easily pick out the triangle. Then remove the rest of the square and look for light scoring in the liner. If the liner isn’t scored at all, you haven’t cut all the way through the adhesive and a little more force is a good idea.
On the other hand, if the liner is deeply scored, you've gone to the other extreme. Lighten up the cutting force or check the blade depth to make sure your plotter blade isn't sticking too far out of the blade holder.
If you’ve done a test cut and it looked okay, but you’re still having trouble weeding the edges and corners of your graphic, crank it up a notch; a little more blade force should do the trick. Also bear in mind that not every film is made the same. Some come on a release liner with very little adhesive. These films are very easy to weed because the adhesive is heat-activated and isn't tacky when you're weeding the film.
Others come on what is known as a self-adhesive carrier or liner. These films have a tangible tackiness to the liner which holds the face film tightly in place until you grip it and start pulling. These will require more effort. If you're accustomed to a low-tack liner film like HotMark, using something like Quickflex or EasyWeed that has a higher tack level, will make it...a little less easy to weed.
That doesn't mean the film is defective. it's just different. The benefit to a higher tack liner is the fact that you can weed more aggressively knowing that only what you pull comes off. And if you goof and pull up something you didn't intend to, you can put it back in place and the self-adhesive carrier will keep it in place until you transfer it to the shirt. You might say it's goof-proof. Yes, it’s that easy
If it doesn’t stick, check the heat press to make sure the actual temperature is what's displayed. Let it cool for a few more seconds, or use a little more pressure. Make sure you have the right film for the fabric. Don’t mix hot and cold peel films in layers. Give your customers good garment care guidelines. If the color is shifting, get some better shirts, switch to a Universal low temperature film, or choose a dye-block film. If it’s too hard to cut, make sure the film is loaded properly, make sure you’re using the right blade, that it's properly installed, and that it isn’t worn out.
Following these basic t-shirt vinyl troubleshooting guidelines will help you reduce costly downtime and enhance productivity.
*Many refer to the garment imprinting material (or t-shirt transfer) as heat press vinyl (HPV). It is not a vinyl, but heat press material, or thermal transfer material; most likely Polyurethane. Sign making self adhesive vinyl is made from PVC (poly-vinyl-chloride) and is always used on doors, windows, and cars. Vinyl is NEVER applied with heat and NEVER applied to T-Shirts.
