Miniature University Workshop: Mold Making
Lesson #2
Instructor: Mary Ann Stage
Email Mary Ann with questions: [email protected]
Visit Mary Ann's website at: http://www.picturetrail.com/ssmaryann
Two-Part Molds, Part 1
Materials/Tools Needed:
A 3-dimensional item to mold
A piece of ¼" or ½" Foam Core Board depending on size of item
Masking tape
Glue
Small ruler
Permanent marker
X-ACTO or craft knife
Wood stirring or popsicle sticks
Rubber Bands
Sandpaper
Paper Towels
Small, flexible, plastic cups you can throw away
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.
2-Part Casting Resin (from Micro-Mark)
Rubber to rubber mold release (from Micro-Mark)
Floral Clay
Flat surface to work on
For this lesson, I'm showing you how to make a two-piece mold of a 3-dimensional object. The first thing you need is an item to mold. I used a lathe to make a pedestal out of a piece of wood that I used for all the statues in my Museum Castle. 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.
Next, make a box about 1" or so larger than your item on all sides with foam core board. Tape it securely. When the box is complete, take the floral clay and work with it until it is about ¾" to 1" thick and will fit into the bottom of the box filling it right to the sides. Smooth it as flat as you can. Position your item with the bottom of your item touching one side of the box edge. This will make an entrance to pour the resin later. Next, put some talcum powder onto your item and press it into the clay so that it goes into the clay ½ of the way. You can put a mark on your item showing a halfway point. Be sure to remove the clay from the bottom of your item on the one side. Push the clay gently towards the item making sure it is tight against the item. This will be half of your 2-part mold. On all four sides of the clay around your item, make an impression into the clay with the end of a pencil. These will form locking keys to make sure both parts of your molds will align properly. You'll see how it works later.
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. 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 and the clay until it is completely covered and about another inch or so higher. It helps if you mark a line 1" 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 carefully cut two corners of the box and pull one side of your box down and pull away two other sides until you can pull the whole piece (clay and rubber) out. This way you won't have to make another box. You can use the same box for making the second part of the mold, which will be in tomorrow's lesson.
