Which vacuum pump and vacuum chamber do I need?

Which vacuum pump and vacuum chamber do I need?

What started as a hobby suddenly takes on a serious form. Where you were initially satisfied with “quite a nice casting”, you suddenly become critical. Like a true “casting grandmaster” you mercilessly reject one creation after another. Air bubbles... far too many air bubbles!

It is high time to expand the hobby with an essential accessory: “the Vacuum Pump”.
With its buddy “the vacuum chamber” this pump forms a duo that will rid any mixture of its air.

With all its gauges, hoses, taps and buttons, taming this machine seems like quite a job. In addition, such a combination is not exactly cheap and therefore quite an investment. Your first questions will therefore be: how does such a thing actually work and what should you look out for when choosing the right pump? Below I will try to explain what to look out for and how to use the vacuum pump.

First of all, it is important to know what a vacuum actually is. You speak of a vacuum when a “negative pressure” is created in an environment. That is, remove the air from an environment (in this case the vacuum chamber) and the negative pressure will increase. When the air is removed and the negative pressure increases, a vacuum is created.

Source: Eurovacuum

Enough theory! Which pump do I actually need?
All our sets consist of a pump, a connecting hose and the vacuum chamber.
Points to consider when purchasing are:

• The size of the pump: the larger (and often more expensive) the pump, the faster it will bring a chamber to maximum negative pressure. With a larger chamber you generally also choose a larger pump.
• The size of the vacuum chamber: the smaller the chamber, the faster the vacuum is reached. Do make sure the chamber is big enough for your “favourite mixing cup”.
• If you use the pump with a fast-curing resin or silicone, it is of course not convenient if the pump takes too long to degas the mixture. Valuable minutes are lost on degassing and the mixture already starts to cure before you have started pouring, so not convenient. In that case, choose a faster vacuum pump and/or a smaller vacuum chamber.

The pump has been ordered and is ready in front of you. Even if you are not technically minded, installing it is a piece of cake. Everything you need to get started is included in a set. Add oil, connect the hose, fit the tap, place the rubber ring with the lid, plug in the cord and off you go. That’s it!

User tips, here they come:
You have of course been mixing like mad, I mean... you have a vacuum chamber now, so you might as well go all out when mixing. The result? A mixture full of air bubbles! We urgently need our vacuum pump :)

1. After mixing, place your mixing cup with the airy mass in the vacuum chamber. Close all taps, place the rubber ring on the edge of the vacuum chamber and close the lid. Call your housemates over and let the spectacle begin!

2. Switch on the machine (often simply by plugging it in) and let it do its work. You will see that little to nothing happens at first. After a while, something starts to bubble and the mixture increases in volume. Shortly afterwards the mixture reaches its maximum and will start to “collapse”. In a fraction of a second the larger volume returns to its original volume. At that moment the degassing is complete.
Letting the pump run longer will do no harm, but generally has little benefit.

3. Using the tap, carefully let air flow into the chamber so that the vacuum is released. Do not let all the air into the chamber at once, as there is a good chance the silicone will end up on the inside of the chamber... Trust me, personal experience ;)

4. Tadaa, your first degassed mixture is a fact!! You may be a little disappointed… The mixture still contains air bubbles!?
Don't worry, this is perfectly normal. These air bubbles will (unlike the other air bubbles) quickly disappear during pouring or shortly afterwards.

5. If you are going to be degassing a lot and work in a small space, we recommend using a filter!

6. The supplied oil for the pump lasts a very long time, but if you have really become a vacuum fanatic you can order new oil here :-)

Source: Eurovacuum

Tips to bear in mind:

• Continue degassing until the mixture "collapses" on its own.
• Very fluid mixtures (low viscosity) hardly increase in volume and therefore do not collapse. Simply let these mixtures bubble away for a while. It looks like boiling water.
• The more viscous (syrupy) a mixture is, the more it will increase in volume.
• Silicone expands about 5 to 6 times in volume before collapsing. So use a mixing cup that is large enough. A mixture of 200 ml silicone therefore requires a cup of 1000 to 1200 ml.
• An epoxy or polyurethane generally increases less in volume than silicone. To be on the safe side, use a mixing cup in which the resin can grow about 3 times. A mixture of 200 ml resin therefore requires a cup of at least 600 ml.
• When degassing a mixture, the volume increases more in a narrow, tall mixing cup than in a wide mixing cup.
• If the cup turns out to be too small after all and the mixture threatens to overflow, do not panic but carefully (with the tap) let a little air into the chamber. The mixture will then sink a little. Then close the tap again and let the mixture rise again. Repeat this until the mixture “collapses”. If you prefer not to let any air into the chamber, it often also helps to tap the vacuum chamber carefully on the table. The vibration often helps the collapsing too.

Price and brand

As with all machines and electrical appliances, price is often linked to a certain quality. Do you choose a premium brand, or do you go for unknown quality and unknown warranty conditions? It is all a matter of choice. Siliconesandmore.com chooses quality brands such as Induvac and Eurovacuum. If you are looking for a specific type of vacuum pump or degassing chamber, please contact us via info@siliconesandmore.com. We are happy to help!