I really like candle making. Despite the mess, the cost of materials, the burns, and the constant fear of spilling hot wax over everything I hold dear, it’s completely worth it. If you remember, a long time ago I made a set of candles cast from impala horns. I’ve wanted to do more projects like this, especially as I ramp up to doing an absurd huge candle project based on much larger and more elaborate horns.
The process started with taking an antique apothecary bottle, cleaning it up, and cutting up some cardboard to form a mold box. I waxed the cardboard, made some clips to hold everything together, and marked out where I should build up the clay to form the first half of the mold.
I sculpted the form that the silicone would conform to out of a ceramic clay. I really like this material because it’s very easy to sculpt and can be smoothed out with a makeup sponge. It also gets softer as you add water, so you can adjust the firmness of the clay by wetting it or letting it dry a bit. I sculpt with the mold box off so I can make sure the seam between the clay and the form is as perpendicular as possible. After it’s smoothed and finished, I add the mold box back in, make sure there’s a watertight seal between the clay and the box, and get ready to pour. Ideally here is where you seal and release the mold. I will detail why that is important in a bit.
Over time I’ve gotten a good sense of volume. I can usually eyeball how much liquid is needed to fill up a mold without going too far over. However, if you want to know objectively, you can calculate the volume with a ruler or fill the mold with rice and then pour it into a graduated container.
Next comes mixing and pouring. I mixed up my silicone in a plastic tub with a pair of chopsticks. It’s nice to have a digital scale handy so you can get the measurements precisely. Over time I’d like to find a solution for the sticky, staining, smelly, perpetually goopy casting materials always sloughing over the sides of their containers and wrecking havoc on all the furnishings. I feel like all molding compounds should come in laundry detergent containers. I always pour my material in a high, thin stream so that any bubbles I’ve mixed into the material pop as they get stretched along the little rivulet of silicone.
Now, I need to explain something before I detail the epic screw up that follows. Mold making is the art of getting everything right. It’s similar to playing an old arcade game. The way that you keep going forward is to pay attention, do everything that’s required of you with perfect precision, and not die. There are so many process involved (sculpting, cleaning, sealing, releasing, making sure everything has watertight edges, picking the right materials for the job, being sensitive to when your material has fouled or is past its expiration) a small mistake or omission almost universally ends up in starting the whole process over. You can think of it like N+ except starting again from the beginning involves several hours of waiting, scraping things off of other things, and going out to buy new and expensive consumables.
So, what I forgot to do was wax the bottle. It’s a little thing, right? I hadn’t realized that glass could adhere to silicone (which is why you should always ask pappy Google before embarking on a project) and didn’t think to apply a sealant or a release to it. The glass and the mold ended up sticking to each other like a crusty pan scab on a poorly seasoned cast iron pot. I was able to prize the two apart, clean things up a bit, and rescue the mold, but it could have turned out much worse.
I was able to pour a new half, finish the mold, and get some castings out without too much of a hassle. I’m exceptionally pleased with how everything came out. I suspect I’ll put up an instructable on the process soon. Also, the resulting candles will shortly be available on Sleek and Destroy.