Mold Making and Casting

Mold Making and Casting - 1 Part
Here's a great DIY project from Mary Ann Stage

There are other ways to make molds and other materials but, this is the way I do it:

Supplies:

1. An item to mold
2. A piece of ¼” or ½” Foam Core Board depending on size of item
3. Masking tape
4. Glue
5. Small ruler
6. Permanent marker
7. X-ACTO or craft knife
8. Wood stirring or popsicle sticks
9. Small, flexible, plastic cups you can throw away
10. Liquid Silicone Rubber (I use One-To-One/Rapid Mold Making Rubber from Micro-Mark). There are other products you can use but, this is what I use.
11. 2-Part Casting Resin (Also from Micro-Mark)
12. Paper towels
13. Sandpaper
14.Flat surface to work on

LESSON 1:
For this lesson, I’m showing you how to make a simple one-piece mold. The first thing you need is an item with a flat surface. I bought a rubber, toy lion and cut off the head cause that is what I wanted to make a mold of. The head then had a flat surface I could use. I usually work on a large piece of plywood cause your work surface can get messy and a flat surface is good for keeping your work flat and putting your finished molded object onto so it will dry flat. I also keep plenty of paper towels handy for spills

Take your item and glue it on the bottom of a small plastic cup or you can make a small box out of foam core to glue your item into. If your item is small you can just use the plastic cups instead of making a box as long as there is about ½” space all around your item. If you choose to make a box out of foam core, use your craft knife to cut the foam board and tape the sides and bottom together with glue and/or masking tape securely so you will get no leaks. What I’ve found is you can cut your foam core through the paper only on one side and fold up for your sides. Do this on all four sides of your box then pull off the square foam part on the corners only, leaving the paper only on all four corners then, simply fold the sides up and tape securely and there will be no leaks. (Sorry if I haven’t explained this clearly but the picture might make more sense) Then, glue your item in the middle of the box and let the glue dry.

Next, measure out equal parts of rubber silicone – part A and part B. I use the small plastic cups marking an A on one and B on the other. I also mark a line on the cups showing how much I pour into each cup. It’s kind of a guessing game to figure how much of both parts you need to cover your item. If you don’t have enough the first time, you can always mix more and add it to your box since it takes 4 hours to cure anyway Next, pour both A and B cups into another bigger cup and mix thoroughly until the mixture is one solid color. Part A is usually a white color and B is usually blue so, you can see when they are completely mixed. This can take up to 3 minutes depending on how much you have used.

You can use a brush to paint a thin layer of the rubber onto your item to make sure it goes into all the cracks and spaces. This is to insure there are no air bubbles. Then pour the rest of the mixture over your item until it is completely covered and about another half inch or so higher. It helps if you mark a line ½” over your item, then you will know when to stop pouring. The set up time for the mold is 4 hours so now you can rest after you throw away your 3 cups and mixing sticks!

After the 4 hours you can take your box apart or cut your plastic cup up to your mold and simply pull your mold out. The rubber mold will be flexible and allow you to gently pull out your original item. You now have a mold to pour resin into and make as many items as you need for your project.

LESSON 2:
Mixing and pouring resin in Lesson 2

You now have a flexible rubber mold to pour resin into and make as many items as you need for your project.

First, using new plastic cups marked A and B, pour equal amounts of the resin in each cup up to your marked lines. There is only a slight color difference in the two parts. Pour both A and B cups into another larger cup and mix thoroughly until the resin is clear – usually about one minute. This resin starts to cure fast in 3 minutes so I usually stir the mixture for about one minute until I feel the cup getting slightly warm then pour it into my mold. Let it set for about 10 minutes in the mold until the resin turns completely white and feels hard to the touch. I usually gently pull the mold away from the now resin item then it’s easier to pull out. The item will be somewhat flexible when you first take it out but it will firm up quickly. This is usually the time to trim any mistakes away. I also keep sandpaper near to sand the item flat after it has firmed up. You can also sand any other parts of your item when it is totally set then paint it. I use regular acrylic paints.

This is how I used the lion heads on my Museum castle walls. The same procedure was used for the door. I needed 8 doors so I made one out of wood and added other pieces to it. Then, I made a mold. From that mold I made 8 resin doors and painted them as you see in the picture. Again, I did the same for the lion fountain, my windows, and whatever else I needed lots of for my project.

Happy Molding!

ã 2003 Mary Ann Stage