About understanding vacuum

It is not my intention to give a lecture on vacuum, nor to be complete in my explanation. For background information, see Wikipedia or any other encyclopedia.

In composite practice, however, it helps to know a bit more about vacuum pumps, measurement units, and a few common pitfalls. When I started my composite adventure, I really missed a short, composites-focused explanation of vacuum—written in a way I could actually understand. With vacuum resin infusion, the devil is in the details, and those details make all the difference.

So if you want to run vacuum infusion successfully, a little extra knowledge—and a better intuitive feel for vacuum—is a good place to start.

I’m not writing this only for future vacuum infusion enthusiasts or visitors to my website. It is also a refresher for my own understanding of the subject.

And as for my composite workmanship: after a steep learning curve since the early days in 2000, it has now reached an acceptable level.

So, to all future vacuum infusion enthusiasts—here it is.

The purpose of these chapters was not to turn the reader into a vacuum specialist, but to provide enough understanding to work with vacuum in a controlled and predictable way. In vacuum resin infusion the margins are small, and it is precisely the details—units, gauges, leaks, vapour pressure and pump behaviour—that determine success or failure.

Most problems encountered in practice are not caused by a lack of equipment, but by misunderstandings about what the equipment is actually doing. Once the principles are clear, vacuum becomes a reliable and manageable tool rather than a source of uncertainty.

This overview reflects my own learning curve over many years of composite work. It is written as much for fellow builders as it is for myself—a reference to return to when things do not behave as expected.

With this foundation in place, vacuum infusion stops being mysterious. It becomes what it should be: a repeatable process, driven by physics, not by guesswork.