Humidification in a pneumatic build material transport system

A memory having instructions thereon that when executed cause a pneumatic build material transport system in an additive manufacturing machine to:

• generate a stream of air;
• add moisture to the stream of air at a first location;
• introduce a build material powder into the stream of air at a second location downstream from the first location;
• remove build material powder from the stream of air at a third location downstream from the second location;
• determine a humidity of air in the stream of air;
• and
• based on a determined humidity, adjust a rate at which moisture is introduced into the stream of air at the first location.

A flow control process for a pneumatic build material transport system in an additive manufacturing machine, the process comprising:

• pulling air through a conduit in a stream of air;
• adding moisture to the stream of air at a first location;
• introducing a build material powder into the stream of air at a second location downstream from the first location;
• removing build material powder from the stream of air at a third location downstream from the second location;
• measuring a rate of flow of the stream of air at a fourth location downstream from the third location;
• and
• based on the measuring, adjusting the rate of flow of the stream of air by changing a rate at which build material powder is introduced into the stream of air and/or by pulling harder on the air.