Hello,

I recently bought the starter kit for VI. I follow the instructions in the video and I am getting a vacuum pressure of around -27.5 but when I clamp off the bag between the vacuum bag and the vacuum chamber, the vacuum gauge goes immediately up. Why is this happening? In the video it stays where it is. Is there a leak in the vacuum chamber? do you have any tips how to check this? many thanks

SH

The easiest way to do this is a drop test. Clamp the vacuum and the resin feed hose and come back an hour later. If the bag is just as tight as when you left, your seal should be good enough for an infusion.
I myself use a vacuumeter (vac checker by dd  compound). I know how much pressure my vac system reaches when everything is tight, and I work at the tacky sealing till I reach that pressure (wich depends on wether conditions too). The advantages of that method are the saved time for the drop test, and instant feedback when I am working at the sealing close to a leak. Keep in mind that a vacuum gauge like yours is not accurate enough for this method. Using a digital vacuumeter was certainly a game changer for me. It cut down my bagging times almost by 1/2.

I would not recommend using double tape sealing. This just complicates things and therefore makes every individual seal less likely to be perfectly tight. Remember that even with this method at least one of the seals have to be perfectly tight. Two almost tight seals are just as good as one almost tight seal. And the problem is usualy just not enough work on the sealant tape, and a double layer doubles that work by definition. With double the work at just one round of tape you will almost certainly get the better result. So focus on one seal, to make it perfect, and not complicate the process with another seal.