I am 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 so on equipment is a must, my answer most often is, "It will depend. " That is bad, I am aware. So the purpose of this article is to provide the specific answer you are looking for.
For everyday mold making and casting, you can pour your materials in a high, narrow stream into one corner of your mold package to reduce the inevitable air bubbles. This allows air to escape as it travels down the narrow stream when you are serving. Vibrating the mold, or mold box helps, as well, either mechanically, by knocking on it with your knuckles, or by putting a vibration source against the mold container, like a hand sander. These kinds of are all great studio room tricks that will definitely reduce air bubbles. Nevertheless 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 topic and acquire the right type of equipment to achieve professional results. Just as one can do that is carpentry using manual operating tools for instance a hand saw, better and faster results are often obtained through the electric saw or slice saw. The right tools, for the right purpose, go a long way in reaching regular satisfactory results in any industry or hobby for that matter.
"What is the difference between the two and do I want both" are the essential questions I most often receive. As the brands imply one chamber provides air pressure even though the other removes air pressure. Nevertheless only one actually eliminates air from your mildew making and casting materials - the vacuum step, while the other simply hides it--the pressure weed.
The pressure chamber works by providing up to 50-psi of atmospheric pressure. If you remember your high school science, normal sea level pressure is about 14. 7- psi. Hence, the greater pressure works to compress any air pockets 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 see the pockets now. But, once you release the air pressure back to 14. 7-psi, air bubbles will return - that is unless of course air is contained as it might be if the material you were pressurizing solidified to a solid, like a hard resin, gypsum plast typer 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 rubber back to normal size, even though your rubber has cured.
Thus, the pressure container is best suited whenever your mold making or throwing material cures to a good and the vacuum holding chamber is employed to remove air from flexible rubbers. Typically the vacuum chamber can also de-air solid resins and epoxies, too. But since it takes a lttle 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 holding chamber can be evacuated.