When you first turn on the pump the resin will foam up considerably and if you are not watching to open the valve a little it will be sucked into the pump and you are done . So if you use a pvc pipe you need one that is clear to watch the level of the resin as it foams , you have to open and close the valve over and over for about 5 minutes till the air is out of the chamber and the resin will settle down and stop foaming , you can then have the valve closed till your vacuum process is over which can sometimes be 24 hours more or less . I've never used wood hardener but I've stabilized a lot of riser wood using acrylic resin .