Filled with original Stay-Clean acid flux, the pen has high quality bristles and a spill tight cap.
1) Before first use, twist the non brush side of the pen, it can only go one direction, until the air bubbles are gone
and it begins to dispense flux.
2) Once the flux begins to dispense for the first time wipe it on a paper towel to insure there won’t be too much
3) Each additional use only requires a few twists of the cap and light pressure to control flux usage