Table of Contents
Recycling my candle wax collection
Prepare the container
I chose a plastic bottle as the outer container for my mold. It’s one of the tougher grade that are used in Germany as deposit bottles. It has a little dome at the bottom, that will yield a perfect space in the mold for the excess wick when casting candles later…
The candle is gonna be in there upside down, so i measure the distance from the top of that inside dome to the bottom of the candle, add a little safety margin and put a mark there on the bottle. I cut the bottle at that mark using some kind of metal saw. Then, i clean the edges with sand paper to prevent any plastic particles from ending up inside the silicone.
Next, a hole has to be drilled into the bottom of the candle, that serves as a way out for the wick of my positive “master candle”. I use a 3mm wood drill (for its pointy tip) on low rpm in order not to melt anything but rather drill it. Afterwards, the cutting edges are cleaned from both sides using a larger metal drill and small file.
The bottle gets a final washing in warm water and is dried with a towel.
Assemble the matrix
Now comes the tricky part: Keep the master candle in the center of the bottle during molding. Wire is our friend here (Well, wire, you turned out to be a loyal friend in many situations, not just this!). A spare length of twisted copper wire can be stretched a little to make it look like new ;)
A plastic bag protects the assembly while we’re preparing the silicone rubber.
Where the rubber meets the road
There is that pack of “Mold Max 60” whose package says “160522” - i guess that means it’s no longer good. But let’s try it anyway. Better than throwing it away straight. The package claims a Pot Life of 40 minutes and a Cure Time of 24 hours. That means i have 40 minutes after initial contact of the two components to get everything poured. Sounds doable.
Having read the safety instructions that come along with the product, i opt to wear gloves during the entire process. Also, this stuff stinks, so a breathing mask is recommended as well.
Ehhm, how much of that stuff do i need by the way? Should have measured the before putting the candle inside that bottle… Okay let’s do an estimate:
That means we’ll prepare a bit more than half a liter to have a small safety margin. The mixing will take place on a scale, because that’s more precise than measuring by volume. So how are we gonna translate that volume into a weight? Right, we need to know the density. Luckily, the datasheet tells us all relevant properties of the material. “1.45 g/cc” it says. I hope to interpret this correctly as 1.45 gram per cubic centimeter, which would be quite realistic - one and a half times as heavy as water…
Okay so is the same as . So we can just multiply 0.6l by 1.45, which equals use the whole fucking package. Thank you, math!
Alright, now here’s the procedure:
- Wash and dry the beaker
- Stir the silicone (part A) - carefully, not taking any air inside
- Shake the compound (part B)
- Pour the whole of part A into the beaker
- Pour part B on top (100:3 ratio)
- Carefully stir again
- Skip vacuum (lacking suitable appliance)
- Vibrate & let it settle a while
- Pour everything slowly into the bottle, onto the same spot the whole time.
The pouring was quite a challenge. It turned out difficult to pour the thick silicone into the small gap between the bottle and the candle inside. The whole thing took a while and towards the end the silicone wouldn’t even want to flow anymore really. Yet, i managed to get that stuff in there and with the help of gravity and some tiny vibrations i hoped that no air bubbles would remain touching the candle.
Recover the mold
Two days later…
I use the tiny buzz saw i once got for building special lamps to cut the bottle open.
First, i was drilling a few holes in there to create four “lids” that could bend open. But the silicone layer was to thick, so i started slicing it off. The second slice already got too thick, so my mold was entirely open then. Now it’s easy to fiddle out the master candle. The small hole at the bottom lets air flow inside, otherwise it could be a bit tricky.
A quick inspection shows that the mold is almost entirely smooth, except for a small dent at the very bottom. Well, i’ll get over it… But on the outside i notice a long crack. Not sure if i should add some tape to prevent it from tearing all the way through.
Casting candles
Wax melting and filtering
By not directly heating the wax, but rather using steam for the task, we know that the temperature will be close to 100°C, and there is no risk it vaporizes.
I opt to put the filter paper directly inside out melting pot in order to contamine only one container with wax. The price of this is that i need more energy to melt all the wax because of worse initial heat transfer.
I use some kind of disposable cotton cloth usually used for cleaning to filter the wax. Hopefully this is is gonna be sufficient. Otherwise the wick will clog up, rendering the candle unusable. But hey, in that case, we’ll turn it into a new one. A better one. Because we’ve learned something.
Wicked wick
I heard that candle wick has a flow direction. This means it’s gonna work well if you put it in the right way (liquid wax flowing from bottom to top of candle), and bad if you do it the other way round. So there should be a mark on the roll telling me where the top is. Well, looks like i’m on my own with this. I check the weaving of the wick on my master candle to see that the arrows face downwards (V). So let’s try it the same way and see if it works.
To properly soak it with wax, i give the wick a short bath prior to casting.
Then, the wick is threaded through the bottom hole and fixed at the top with the wire from earlier. Two or three centimeters are left protruding through the bottom, allowing us to light the candle later. This short piece goes into the cave that our bottle created through the dome its base. The stiffnes of the dipped wick makes all of this quite easy.
Final mess
No words on this…