Humidity and temperature
Your working environment temperature ideally should be between18-30°C, with
relative humidity (RH) between 40%-60%.
These are very important factors to consider for an optimal printing experience.
How you will notice high humidity affect DTF film and DTF powder?
Generally if you exposed your DTF PET film or DTF powder to the air, they will absorb moisture from the air. You won't easily notice this until you start to use them for your printing, when the effect will be clearly visible on the film.
Normally when the film passes over the pre-heat plate, if the film has moisture, some of it will evaporate from the film. But if it was a high ratio of moisture, the duration of the film passing over the pre-heat plate to the sprinkling powder area is too short to eliminate all the excess moisture. You will notice that the powder will adhere to the film in these areas where there is still excess moisture.
How moisture affects the print/ design art?
When the film contains moisture, this moisture will evaporate into the ink and as a result the ink will take longer to dry. If the ink has not dried sufficiently and the powder is applied to that part of the print, more powder will stick on this area, causing an uneven cured surface. This will make the peeling process difficult and some parts of the print could come off during the peeling process.
In addition to this, you may notice tiny bubbles under the powder surface. Those small bubbles accrued when the powder captured the excessive moisture from the film underneath. See figure 1
If you leave the print for a couple of days, the condensed moisture will start to release from these tiny bubbles (in the form of water). This looks like the print/ film is sweating.
Trouble-shooting:
1- Usually, moisture gets into the first one to two metres of the exposed film. The amount that is affected this way will depend on how high the humidity is and for how long the film was exposed to the air. If your PET film has not been wrapped in an airtight seal, we'd recommend cutting off the first metre or two before you start to print with it.
2- Get rid of the excessive powder on your film outside the print by tapping on the back of the film or using a soft brush on it.
3- If your powder in its packaging has excess moisture in it, put it to on side and use a new bag of powder. Place the one with moisture in it in a container (with a lid to seal it) with a couple of silica pouches (to absorb the moisture) and leave it for a couple of days. You should then be able to use it without any issues.
Note: To avoid moisture problems with your DTF PET film whilst you are not using it, it is a good idea to wrap it in a plastic bag. Also, it is a good idea to put your DTF powder in an airtight container and put a couple of silica pouches in the powder if you don't think you'll use it for a while. You can also place a couple of silica pouches in its aluminium bag and seal if you'd prefer to keep it there and store them in a cool dry place.
Make sure to have indoor temperature and humidity meters near the printer to keep them at the right levels.