DTF film has a coating that releases the ink when it is heat pressed onto the fabric or product. This coating is a water based product that also attracts and reacts to moisture and is susceptible to static electricity.
During the colder damper months in the UK the coating on the film can absorb moisture, this can cause it to attract the adhesive powder in areas where it is not required. Moisture enhances the films ability to disperse static electricity, your finishing unit should be earthed to allow the normal levels to drop out. During the colder periods of the year in the UK or in high levels of humidity you may find the powder is more difficult to shake off the blank areas of film. There are several tips that can help in these circumstances.
Make sure your roll of film is at room temperature (18c - 22c) before starting to print.
Turning up the temperature on the film bed to 60c can help, bizarrely reducing it to 40c can also help when using low ink coverage.
Do not be tempted to turn film paddle (beats the powder off the film) up to high as this will only generate more static electricity and increase the problem, unless using an ionising bar.
Make sure the film path from the printer and the powder chamber are cleaned with an anti static spray, the paddle blades also. The more powder on the walls of the powder chamber the worse the static.
In severe cases a powered ionising anti static bar can be retro fitted into your powder machine. This must be done by a Resolute technician if your equipment is under warranty or covered by an extended service agreement.
If powder is sticking in the warmer months this could be caused by your humidity being to low. The optimum humidity is 60%, you can increase this with a humidifier if you need to.