Making Molds for Metal Casting at Home
Whether it’s a metal part you need to reproduce, or just something that would look cool on your bookshelf, creating molds is an easy way to cast metals at home. You can also buy ready-made mold from DAWANGCASTING.
What do I need?
All you really need for mold making are some basic ingredients and tools. These include two hand soap containers, some newspaper for the work area, wood glue*, clean water, two mixing bowls (one should be glass), a spoon or stick to mix with, knives/razor blades for cutting the container components apart, and finally your mold material. *You can use any type of glue that will remain flexible after cure time; 5-minute epoxy and rubber cement are both great options.
I’d also recommend getting a spray bottle to keep the mold material moist while it cures and some masking or painter’s tape for keeping your molds together.
What kind of metal will I need?
Basically, any type of metal can be cast in a silicone mold, but it’s best to have a pure metal ready. Pure metals are not the same as commercial grades, so if you can find some from another source or live near a refinery… try there first. If the metal isn’t pure, melt it slowly and constantly stir to remove impurities.
How do I create a mold?
For metal casting, Molds are generally easy to make, but there is a bit of technique and some simple math involved. There are three basic steps:
1) Cut apart your metal into 2 or more pieces that can fit in the container you plan to use for mold making. For example, if you’re using two ketchup bottles… cut them so they will lay side by side with no overlap when glued together.
2) Glue your metal pieces together with your chosen glue (if it is not already done). Let this dry overnight before moving on to the next step. Once dried, sand and brush away any excess glue and check all sides with a magnet to ensure the bond is strong enough for casting.
3) Pour or brush enough molding material into your container to completely cover the metal. Allow this coat to harden for at least 30 minutes before applying a second layer, making sure it does not dry before you are finished with the whole mold.
After your first two layers have dried, continue adding coats until you have reached the desired thickness of your final product. Generally, around 1/4 inch is fine unless there are design considerations that may require thicker walls. Repeat the same steps with another color if necessary for complex designs.
Why do I want it thick?
Thickness allows for more detail in the casting process and makes cleaning easier due to less thin areas where impurities can build up (remember… once the metal has cooled down, it can’t be patched, so no bare spots).
How do I make a pedestal?
There are two types of pedestals that are commonly used in mold making. The first is made with threaded rods and bolts, while the second uses clay.
To create a pedestal using bolts, you will need some thread rods, matching nuts, and bolts to fit your container diameter. Drill or punch holes into both cans, then tap threads onto one side of each container by matching the bolt pieces. Securely attach these together inside your container before continuing on to step three above.
What about clay?
You’ll also need a sheet of metal or thick plastic to make your mold release, some modeling clay, and an old rag for this method.
What about my parts?
Once you’ve cast your final product (or any part that comes out of the mold), shake off the excess material and place it onto your metal or plastic sheet, then cover with your modeling clay or spackling paste. Be sure to press down around all edges to prevent shrinkage during cooling. The resulting pedestal should be slightly larger than the piece you want to create so that a bit of sanding will be necessary before painting/finishing. You can read more of our different articles to get more clarification.