Using clay for your metal casting molds may or may not be beneficial to your project. It can be a sensitive material and will not always work for your specific needs, however, it can be used for small special projects.
It is suggested that casters use Polymer Clay if they are attempting to make a mold. Polymer clay is a modelling clay, able to be hardened using a furnace or kiln. Polymer Clay does not contain clay minerals but has mineral clay properties like having to fire the clay to harden it and adding liquid to dry particles giving it gel-like properties. Other Clays could be used; however, polymer clay is the most commonly used for clay molds.
Steps. So..actually how to make a clay mold ?
Create your mold using clay. Make sure that you have sealed any edges where the molten metal could slip through. You will want to ensure that your mold is completely dry otherwise you risk the mold cracking and potentially exploding due to all the excess moisture inside of the wet clay. To dry your clay properly, you will need to fire it in a furnace or kiln first; letting it air dry may pose the same risks as wet clay.
Once your clay mold is completely dry, melt your metal (polymer Clay is considered a plastic and may start to burn at temperatures above 385 degrees Fahrenheit so it is important to research which types of clays to use for your mold and which type of metals you can cast.) when using clay for your mold, aluminum may be your best choice.
Pour your molten metal into the cast and wait for it to solidify and cool. Once this is done, you can remove the clay and you will have your (almost) finished product.
After a few refinements (sanding, removing excess metal, etc.) your project is complete.
Remember. Clay Mold for Metal Casting
It is important to note that clay should be used for small projects as opposed to large ones. Because clay is not the greatest for making molds, you will likely have many imperfections in your cast and will require a lot of refinement; Not to mention the fact that using clay as a mold can pose risks for the user, as clay could explode or crack. The process of using clay as a mold for metal casting is best for DIY and home projects – something you wouldn’t consider as a professional job, although its not to say you couldn’t get some pretty cool results from using clay as a mold.