Ricoh Ri 1000 Operator Training page 15

Why do you need Humidity?
DTG machines don't like dry conditions. The ink in the head is more
prone to clogs if the air is dry. If you are in a dry area with low
humidity OR, if you plan to put the machine in a room with very dry
heat in the winter, consider using a humidifier.
The ideal conditions are: 45% to 80% relative humidity, dust-free, with
no airflow over the printer.
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