Silicone Molding & Wax Casting
Ever wanted to turn an object into a candle? This tutorial is going to show you how. From start to finish, the whole process from mold making to adding the last details onto the candle is covered here. Feel free to experiment with your own techniques, this is a basic guide to give you a feel for what the process involves.
Here is a list of materials we used
- Lifecasting Silicone
- Popsicle Sticks, Mixing Cups, and Paintbrushes
- Mold Clay (sulfur-free modeling clay)
- Rubbing Alcohol
- A Sharpie Pen
- Plaster Bandages (2 rolls)
- Ultracal Plaster (5lb bag)
- plexiglass sheet 8 x 10
- Paraffin Wax (5.5lbs)
- Acrylic Paint
- Tin Foil
- Hot Glue
- Double Boiler
- Rubber Bands
Choosing the right object to mold is crucial. It should be solid, non-porous, and contain no major undercuts or holes that travel through from one side to another (or else you wont be able to get the mold off). An object that is smooth is ideal, since the texture will carry through on the mold, making de-molding a cinch. I chose this ceramic box with a geometric design. It was created by Pavel Janak in 1911 during the cubist art movement. I picked up this replica in Prague at a museum gift shop.
A few words of wisdom before we start… Silicone hates latex. If you are using latex gloves while handling silicone, it won’t cure. If there’s any residue of latex on the surface of the object or the board, the silicone will have a mottled, gummy surface. Not good. So make sure to wipe everything down with some rubbing alcohol, and if you choose to wear gloves, make sure they are nitrile, not latex. Sulfur also does not get along well with silicone. That’s why we recommend using mold clay that contains no sulfur. Life-casting silicone is skin safe. It is not toxic, and gives off no fumes. It cures in about 2-3 minutes with the aid of a hairdryer, or in about 25 minutes at room temperature.
When it comes to melting the wax, USE A DOUBLE BOILER. You MUST use a double boiler. If wax gets too hot, it can explode. If you use a double boiler, it won’t get hot enough to explode. So be safe, and use a double boiler.
Now that i’ve gotten the scary stuff out of the way, lets get started.
First thing, is to secure the piece to a flat, non-porous board with hot glue. We used a plexiglass sheet out of the scrap bin. Apply the glue to the board first, then set the object onto it. This will allow the piece to come off clean when you’re finished molding it. Do your best to keep the glue from showing at all, or else it will also show in your finished candle mold.
Using the clay, carefully fill in any gaps along the bottom, and smooth it out so it looks as seamless as possible. For our demonstration here, we decided to also fill in the tiny gap between the lid and the base of the box.
Create the Mold
Mix the silicone in one of the mixing cups very thoroughly. For every one ounce of purple, add one ounce of white. (The recipe for this silicone is 1:1 by volume.) It will become an even lavender color when it’s mixed thoroughly. When you’re ready to mix up some more, just peel the remaining silicone out of the cup.
Mix and apply the first coat of silicone. This should be a thin coat, giving extra attention to filling in the details without air bubbles. I used a synthetic hair paint brush to apply the first coat, allowing me to easily push the silicone all over the details of the box. Use a hairdryer on the cool air setting to pop the air bubbles. Then use the hot air setting to accelerate the cure time. About 3 minutes of hot air later, the layer should be cured. Touch your finger to the silicone – if it doesn’t stick, it’s ready.
Apply the next coat, this one doesn’t need to be as carefully applied since our first coat covered all the details. This is more of a reinforcement coat. Cover the all of the object until its entirely that opaque lavender color. If you can see any colors underneath, it needs more silicone.
The third and last coat of silicone is for bulking. This is an important step. The mother mold will be 2 separate pieces, split along the horizon on the object. So take a look now at your mold. Visualize where the center divide will be, and look at it straight on, and close one eye. If there are any undercuts showing, you’ll need to fill those in.Mix up some silicone, and add some filler if you have some handy. I used polypropylene fibers, but sawdust works great too. Because my box was symmetrical on both sides, I added a small mass, or mold key, to one side, so that I always know how to orient the mold into the hard shell.
The final step here is to embed a round pole at the top, about 1/4″ to 1/2″ in diameter. A standard ball point pen works excellent if you gut it, and cut it down to 1″ to 1.5″ tall. This will be pulled out of the mold later. This pole is going to allow the wick to come through the hard shell.
Life casting Silicone is a rubbery material that has great tear strength and lasts virtually a lifetime. It has an elongation factor of about 300%, meaning it can stretch itself up to 3 times its resting size. It’s precisely this feature that requires us to make a hard shell to keep the silicone from collapsing or stretching when you pour the wax into it. This hard shell is called a mother mold.
Making the Center Divide
Look at it straight on, One eye closed, eye level. Using a sharpie pen, draw along the horizon of the silicone. Your pen should be dragging along the last visible plane. You are tracing it’s silhouette. You have a little margin of error here, so don’t stress too hard about it. Do the best you can.
Take a handful of clay, and start making the dividing wall along the line. Bring the clay all the way up to the line, but not over it. It should be about 1/2″ tall.
Smooth it out, and press the butt of the sharpie into it straight on. These are going to be mold keys, ensuring the case fits nicely. An optional step, but highly recommended. Also push 2 Popsicle stick ends into either side of the clay wall. These will be pry holes to split the two halves. Brush Vaseline on them to keep them from sticking to the plaster.
Apply some wet plaster bandages first, without covering the wall.
Mix up about a 1/2 cup of plaster, and apply it over the plaster bandages, and the face of the wall. Make sure plaster gets into the mold keys. Finish with one more layer of plaster bandages over the whole thing.
Once it’s hardened, remove the clay wall, and Vaseline the plaster divide with mold keys (now positive). It’s a good idea to also Vaseline along the top too, in case you get a little sloppy on the second half. Apply the plaster just as you did on the first half. In 3 steps. Remove the top pole and pry sticks before it’s fully cured.
Once it’s all hardened, insert flat head screwdrivers into the holes where the Popsicle sticks used to be, and gently separate the halves. They should slide off with a small amount of force, and if you got the horizon line correct, almost no force at all.
Slowly, and delicately lift the silicone from the board, and off the object. The silicone can rip in the thin sections if you aren’t careful.
Trim away the thin strings on the base. Using an X-acto, make a tiny incision where the pole was, to allow the wick the come through. Seat the silicone back into the mother mold, and make sure everything fits well. Use a couple of rubber bands or zip ties to keep the halves together.
Melt some wax in a double boiler. If you’re going to pour the candle in one section, melt enough wax accordingly.
If the wick is unwaxed, dip it in the wax, and straighten it out. Push the wick through the incision, and pull it out through the hole on the plaster.
I used a stick to help push the wick through the mold. Secure the top to a popsicle stick or something similar, to keep it upright. I used some clamps, but took them off after i realized they were completely useless. You can opt to just pour the whole candle in one section if you like. That’s what i did on my candle. When wax cools, it shrinks, so you will have a depression in the bottom of the candle. Cut the wick, then pour enough wax to fill in the sink hole, covering the end of the wick.
Let the candle wax cool COMPLETELY. This takes several hours. You think you can be sly and throw it in the freezer? Don’t do it. It will cause the candle to crack.
When its cooled completely, remove the rubber bands or zip ties and dissemble the halves. Carefully peel back the silicone, and check out your candle. If there is a lot of pitting, simply dip the candle into some clear melted wax for 5 to 10 seconds to even it out.
I used an X-acto to clean up the sloppy bottom edges.
I needed to add my lines to the candle. This was done simply by painting on it with acrylic paint. I added some black powder pigment to the paint to make it more opaque, this is optional. I taped off sections with masking tape to get clean straight lines.
It was a labor of love, and took quite a bit of time and patience to keep all the lines neat, but I think the final result is pretty awesome. I opted for a slightly thicker line to allow myself a greater margin of error. All it needs now is to be dipped into clear wax to seal the paint.
Grab it by the wick, and gently lower it into the wax, let it sit for about 5 seconds, then pull it straight out, and set it onto some tin foil. This protects your paint details from rubbing off.
Here it is, the final piece. The best part about making silicone candle molds, is that the mold will last you a lifetime. (And it isn’t limited to just wax. Pour plaster, urethane, casting resin, or soap into it. )