How to remove bubbles from resin castings with the vacuum chamber

Tools and materials I propose:

Vacuum chamber kit

Vacuum pump oil

Most people would recommend a pressure pot for degassing resin. But if you use a slow setting resin, the vacuum chamber can really work on achieving crystal clear castings.  

The vacuum chamber kit set up is just a stainless steel container and a vacuum pump. Basically the pump sucks the air from inside of the pot and creates vacuum conditions in it’s interior.

In order for the pump to reach high vacuum, it has to be filled with oil. This is a special oil created for high vacuum pumps.

In order for this process  to be successful, you have to use a low setting epoxy resin. In the video I used a resin that has 2 hours open time, 6-12 hours initial curing and 4-7 days final curing.

My resin also uses 100:60 mixing ratio. So I added Part A and Part B and mixed them really well for about 2 minutes. I also added a few drops of transparent red dye. 

I put the resin in the vacuum chamber and turn the vacuum on. Then I slowly close the air release valve. The vacuum starts to increase. The trapped air bubbles inside the resin, start to rise on the surface. Some people release the vacuum once the bubbles burst. I don’t think that’s necessary. Once the container is about to overflow I turn the pump off and slowly open the air release valve. 

I repeat that process a couple of times more. Each time the bubbles are less and less. Each vacuum session lasts for about 5 minutes, depending on the volume of resin I want to degas.

Once you compare the degassed casting with the non degassed one, the difference is pretty dramatic. Especially under different light situations the castings have tremendous differences.

So to me this definitely works with slow setting resins and can produce crystal clear castings!

I hope you’ll find this tutorial useful!

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