In our instructions, we say that you should try to ensure that there is an inch (2-3cm) of free space inside the zip of a vacuum storage bag before the contents. Is this just a trick to make sure you have to use up more bags? How do you even seal a bag so that the clothes or bedding don’t come up to the edge of the zip anyway? Does it really matter?
Let’s deal with the last question first – yes, getting the best seal on your vacuum storage bag zip matters, because the zip is the most common place of failure in usage. That is to say if your bag is leaking air back in, the most likely place is here at the zip. The first reason as to why you need some space between the contents of the bag and the zip is to straightforwardly avoid overfilling. Many people force as much as possible into a single bag, when multiple bags should be used instead. This is not a cunning commercial ploy to sell more bags – an overfilled bag puts undue pressure on the zip increasing the likelihood that a part of it will pop open and let in air. Secondly, and as importantly, the strip of free space allows the plastic to seal on itself when you suck all the air out, so in addition to the zip, the strip of plastic space sealed on itself improves the longevity of the vacuum. In other words, you get better performance from a bag sealed this way.
So, now we’ve convinced you that leaving that bit of space is important, how do you achieve it? After all, nature abhors a vacuum so don’t the contents of the bag simply move into the space?
The trick, as long as you haven’t overfilled the bag, is to pull the zip outwards as you vacuum, constantly moving from one end of the zip along to the other. If you gently tug it out as you are removing the air, a natural space between the contents and the zip will appear and the vacuum storage bag will seal down on itself. Just keep pulling the zip away from the contents as the bag shrinks down and you’ll end up with a perfect seal on your bag, as shown below.