Difference Between Pressure Pot and Vacuum Chamber

Vacuum Chamber and Pressure Pot are two types of equipment for eliminating material bubbles in mold making and other places. So which of these two equipment is better? The following is a detailed analysis of the difference between Vacuum Chamber and Pressure Pot.

Both are devices to help remove air bubbles from your project: one chamber gives air pressure whereas the other expels air pressure. In fact, only one chamber that is the vacuum chamber which actually removes the air while the other chamber which is the pressure chamber just hides the air. 

In short: a Vacuum chamber pulls the air out of your material using a vacuum and a pressure pot shrinks the bubbles in your material using pressure.

Vacuum Chamber = Air Out,

Pressure Pot = Air in

How a Vacuum Chamber works

The vacuum chamber uses a pump to force air out of the chamber and, subsequently, out of the material. If you’ve mixed up a bunch of silicone and have introduced a lot of air, the vacuum chamber kicks into high gear, pulling all the extra air out of your material through a hose. It naturally pulls all of the small bubbles that are within your silicone, to surface and pop and release.

vacuum chamber

How to Use a Vacuum Chamber

With a pump hooked to the lid, you will place your silicone material in the chamber, place the lid on center, and turn the pump on - this will create a vacuum in the chamber and pull out the bubbles.

From there you have two levers and a gauge on top. Before you turn on the pump, you are first going to close the lever that lets air in – once you turn on the motor, you’re going to see the air start to evacuate (indicated on the gauge). And when you’re ready to let air in, just open the lever.

How Pressure Pot work

A pressure pot is a device that pressurizes the air into microscopic (and thus undetectable) amounts such that the result is virtually bubble-free casts. 

How to Use a Pressure Pot

With an air compressor connected to your pot, you place a casted project in the pot and allow it to cure under pressure. This crushes the air bubbles in your resin.

pressure pot

When to Use a Pressure Pot or a Vacuum Chamber

When using a vacuum chamber, you will be able to easily remove air bubbles from any flexible rubber items. They are also ideal for vacuum degassing liquid plastics for making bubble-free castings. If you are looking to do resin castings or making a mold then a Pressure pot is the way to go.

The vacuum chamber can also de-air solid resins and epoxies, too. But since it takes a bit more time to create a vacuum, and certain resins are fast-cured, the pressure chamber is the tool of choice in those instances as it can be quickly pressurized, faster than a vacuum chamber can be evacuated.

In summary, the pressure pot is used primarily to eliminate unsightly air bubbles in hard setting materials, whereas, the vacuum chamber can be used for both degassing rubber and hard setting materials, but is best adopted for rubbers such as silicones and polyurethanes.


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