Using Tube Molds
One of the most exciting ways to add detail to soap-casting projects is through embedding shapes from a tube mold. Tube molds are just that — long tubes — and they are available in a variety of shapes. You pour the tube full, let the soap inside harden, then push it out. You have a long piece of soap that you can embed whole or cut into pieces.
Use small pipe to make thin rods of soap, larger ones for bigger rods. These also work well for making round bars. You just push out the hard soap and slice! Freezing the soap in the tube makes removal easier.
Some of the simplest tube molds are made from PVC pipe. You can buy PVC at hardware stores and have it cut to length. Buy the caps that fit the ends so you won't have to worry about how you're going to seal the mold. Get the threaded, screw-on ones if you can, as they're the easiest to remove.
You can find stainless steel tubes in animal and geometric shapes at cake decorating stores. They are intended for baking bread into fancy shapes for canapés. You just pour the soap in instead, and you've got a star, a heart, a duck, or one of many other shapes.
More and more soap mold companies are making tube molds, which are sometimes called vertical molds. Some are in two pieces and clamped together. This is for ease of removal; you just unclamp and pull the two halves of the mold free. Other companies make simple one-piece tubes that you need to seal yourself.
Getting the soap out of a tube mold can be frustrating. You can create a plunger with a disk of wood and a stick, you can just push with a broom handle, or you can invest in a pressurized air system. If you don't use tubes often, you won't mind the struggle, but if you do it a lot, you'll need a good system.
Most of the time you spend with this kind of mold is in prepping the mold and getting the soap out of it. You usually make tubes of soap as part of another project, so having a storage container for the specific project at hand is a good idea. You may, of course, also use the tubes as finished soaps.
You need to determine the number of ounces of soap you'll need for the tube mold you're using. For this first recipe, use a one-inch diameter PVC pipe cut to twelve inches long. You should be able to buy an end cap where you buy the pipe, but if you can't find one, use heavy plastic wrap and rubber bands to seal the end. Pieces cut from heavy freezer bags or heavy painting tarps work well. Be sure to keep the end of the mold in a container when you pour in case the seal gives way.
Another method of sealing a mold involves pouring a little puddle of casting soap on the work surface and setting the mold in it so that as the soap hardens it will hold it in place. This works best with molds that would stand up on their own anyway. Tall, heavy molds will tip over, breaking the seal and making a mess.
After you've sealed one end of the tube mold, fill it with water to test it before committing to melted soap. If the water leaks out, you need to readjust the seal. Pour the water into a gradated measuring cup to see how much soap you need to melt.
It is a good idea to support the tube molds while the soap is hardening upright in a pitcher or other tall container that won't be easily knocked over. A small box padded with a towel that can be shaped to hold the mold upright is a simple solution. Or for one thin mold like the one in the recipe that follows, a plastic pitcher and a hand towel should work well. Roll the towel and place it into the pitcher. Make an opening in the center of the roll for the mold to slip into. If there is too much room, use another towel.
Never rinse large blobs of soap, either finished or unsaponified, down your drains. They will clog up almost immediately. Instead, use smart cleanup techniques. Wipe extra soap off tools and scrape it out of the pan. When you're done, rinse everything with hot water. If you've used oils as additives to your casting project, you may need to use a little regular dish detergent.
It can be a challenge getting soap out of tube molds. You will probably have to freeze the soap for a while after it's hard to get it out of the mold.
Take the mold out of the freezer after about an hour. Let it sit on the counter until condensation forms on the plastic mold. Take off the seal and push firmly with your fingers, a broomstick, or other strong object that won't break under pressure. It will take some practice, but you'll eventually find a way to get the soap out.
Let the soap sit until it is back to room temperature and store it in a way appropriate for the project you're going to use it in. If you're going to use the soap as-is, cut it into little disks or round bars.
Basic Tube Mold
12 ounces clear soap base
2 to 3 drops soap colorant (or more as desired)
1 teaspoon soap fragrance
Fill the bottom pan of the double boiler with water, put on the top pan, and turn the heat on high.
Cut the soap base into approximately 1-inch cubes. Place in the top pan. Add two drops of colorant, the mica, and the fragrance. Put on the lid.
When the water in the bottom pan comes to a boil, turn off the heat and remove the pan from the heat. Let sit for about 15 to 20 minutes. Take off the lid. (The soap should all be melted.) Gently stir to combine the mica and colorant. Check for color. If you want deeper color, add more colorant a drop at a time.
Take the top pan off and wipe the condensation off the bottom so that it does not fall into the mold. Place the tube mold upright in the towel in the pitcher; be sure the bottom is sealed. Fill the mold. Set aside to cool. After about an hour, place the tube mold in the freezer for another hour. Remove it, let it sit until condensation forms, remove the seal and push the soap out of the mold. Store as desired or cut into disks or tube-shaped bars.