Garment decoration is a high margin business. As businesses adopt the technology of thermal transfer from vinyl graphics, it is seen that pressure poses the main problem in the process. This is paramount when spot color graphics are applied to fabric through the use of any adhesive-backed film. Thermal transfer films are of different kinds and thus the temperature and dwell time could vary for each kind of film.
Harm causing factors
Other than temperature and time, the pressure needs to vary as well. Too little pressure makes a bad product. The graphic will peel off quickly or after some time. It is thus important to make a nice job of it.
For a majority of the thermal transfer products, there is a certain formula consisting of temperature, pressure, and dwell time. When it comes to CAD films, the need for pressure takes the form of a standard guideline, heavy, medium or light. On a few print applications like dye sublimation, the recommended pressure is printed in pounds. To give an example, a ChromaBlast pressure setting is 60lbs.
Correct pressure is important for a quality product. Thermal film adhesives get activated by both pressure and heat. Insufficient amount of any of these two will result in the film not sticking to the garment. A few film manufacturers have claimed that the output stated by heat press is wrong, and the operator needs a digital thermometer to get the needed application temperature.
Importance of pressure
Heat is only a small component of the equation. Inadequate pressure will make a weak bond between fabric and film. Too light a pressure means the adhesive will not bond with the garment fibers. The latter will be overwhelmed by the stress generated by liner removal.
The turbulence, water, and heat of laundering may also cause the applique to move away in case it has not sealed in a proper manner. Thus there is a possibility that there can be sufficient pressure for the first transfer to be held, and insufficient to be a wash-fast. It is apparent that correct pressure is extremely important. A thumb rule is to put a little more pressure than recommended. Excessive pressure is perfectly okay for most films.
An effective technique to make sure that the print remains fast is to repress that transfer post liner removal. You should peel the liner, and reduce time setting to approximately five seconds, and then press again. This process will assist the film to recover from the weakening effect generated by the liner pulling at the fresh bond between fabric and film.