We are often asked if a vacuum chamber or a pressure pot is required in the fine artwork of mold making and casting. As with so many answers in life, a "yes" or "no" answer is not possible without first learning more information about the task. Except for water clear resin, where tiny air bubbles will obscure the clarity of a piece, and such equipment is a must, my answer most often is, "It will depend. " That is bad, I know. So the purpose of this article is to provide the specific answer you are looking for.
For informal mold making and throwing, you can pour your materials in a high, narrow stream as one part of your mold box to reduce the inevitable air bubbles. This allows air to escape as it travels down the narrow stream as you are serving. Vibrating the mold, or mold box helps, as well, either mechanically, by knocking on it with your knuckles, or by positioning a vibration source against the mold container, like a hand sander. These are all great studio room tricks that will definitely reduce air bubbles. Yet they do not eliminate them entirely. So if that is your goal, continue reading00.
So if you are planning to create conforms and castings on a regular basis then you should bite the bullet and acquire here the variety of of equipment to achieve professional results. Just as one can do woodworking using manual operating tools like a hand saw, better and faster results are often obtained through the electric table saw or slice saw. The proper tools, for the right purpose, help in attaining regular satisfactory results in any industry or hobby for that matter.
"What are the differences between the two and do I want both" are the essential questions I most often receive. As the titles imply one chamber provides air pressure while the other removes air pressure. Yet only one actually removes air from your mold making and casting material - the vacuum chamber, while the other simply hides it--the pressure container.
Stress chamber works by providing up to 50-psi of atmospheric pressure. In case you remember your high school science, normal sea level pressure is about 14. 7- psi. Therefore, the greater pressure works to compress any air bubbles in your material and squeezes them down to almost microscopic size - thus making them appear to disappear. The air remains though, but you just can't view the bubbles now. But, once you release the air pressure back to 14. 7-psi, the air bubbles will come back - that is unless of course air is contained as it would be if the substance you were pressurizing solidified to a solid, such as a hard resin, gypsum plaster or epoxy. If your material was a mildew rubber though, such as silicone or polyurethane, the flexible rubber will not contain the compressed air bubbles and they would expand within the rubberized normal again size, even though your rubber has healed.
Thus, the pressure container is best suited when your mold making or casting material cures to a great and the vacuum step can be used to remove air from flexible rubbers. Typically the vacuum chamber can also de-air solid resins and epoxies, too. But since it takes a little 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.