Creating garment graphics from heat applied thermal film, aka “T-Shirt 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.
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. The most likely cause is insufficient pressure. Everyone focuses on the time and temperature settings and, if the appliqué doesn’t stick, new users tend to increase the dwell time. Wrong move.
- It’s called a heat press for a reason. Pressure is an essential element in the equation. Some films require more pressure, some less. Our best-selling EnduraTex HotMark 70 has a low tack adhesive that requires firm pressure. So if you’re using HotMark and it’s not sticking to the shirt, crank it up a notch and apply more clamping force.
- 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 repellant or antimicrobial coating. Moisture repellant coatings are normally found on products like tents and nylon raincoats. 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. Click here for more information.
- When an appliqué sticks initially and comes off later, it’s almost always because of improper layering or improper laundering. 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 with a standard PU product, the metallic layer must be on top. Click here for more details on layering and overlapping EnduraTex heat transfer film. And here’s the link to the Siser layering guide.
- Another probable reason for initial adhesion failure is a simple fabric mismatch. You put the wrong film on. 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.
- Speaking of which, 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. Some films can stand higher temps, but the cooler the better. This is especially true of cotton garments, which expand and shrink when washed. Thinner films may pucker or wrinkle when applied to cotton and washed at high temperatures. These wrinkles can generally be ironed out by the end user.
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 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 thermo reactive dyes. A garment upgrade will fix this.
- If you can’t change clothes you can change the film. EnduraTex SIR (Sublimation Ink Resistant) is the ideal choice. It’s made with an extra layer that blocks dye migration and preserves the color of the face film. The color range is more limited than that of standard films, so you may not have the option of switching products. If your graphic falls outside the SIR color range, you can add another layer and achieve the desired opacity that way.
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. EnduraTex Glitter and reflective products like EnduraTex Reflex and Siser Reflectall 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 ReflectAll and Glitter, the shorter your blade life will be. Your mileage may vary.
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.
Yes, it’s that easy
If it doesn’t stick, use 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 SIR, or add a layer. 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 guidelines will help you achieve trouble-free T-shirt transfers.
*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.