Cracks in candles

[Mandeville]

I'm trying to make pillar candles about 2-2.5 inches diameter and they're cracking badly - I'm assuming it's because they're cooling too quickly.

I'm using a polycarbonate mould and for my last attempt, I put it inside a length of plastic drainpipe filled with dry sand to act as insulation, and put a cover over the top but that didn't work, it still cracked.

Any suggestions for what I could try next?

 

[MuswellMetro]

I'm trying to make pillar candles about 2-2.5 inches diameter and they're cracking badly - I'm assuming it's because they're cooling too quickly.

I'm using a polycarbonate mould and for my last attempt, I put it inside a length of plastic drainpipe filled with dry sand to act as insulation, and put a cover over the top but that didn't work, it still cracked.

Any suggestions for what I could try next?

your wax could be too hot

I break up a large lump of wax and melt the wax in a baine marie, let it cool until about 68c to70c then pour into molds warmed

i use my honey warming cabinet filed with five brick warmed at 54c to act as the slow oven

i leave them in there for 12 hours overnight

 

[Zante]

Another possibility is to try mixing the beeswax with something else, such as palm oil, to make the mixture a little bit softer and more resistant to cracking.
I was looking up recipes online and the highest amount of beeswax to other component (usually palm oil as I mentioned) was 50%, but I'm sure you can find a way of making candles with more beeswax through experimentation.

 

[chrisb]

wrap the molds in bubble wrap or old tea towel, keep them away from cold areas
cracking can also happen when pats of the candle stick to the mold and split as they contract, make sure they are clean and a little silicone oil or spray in the mold will stop that.

the finish from poly molds should with good wax give you a shine from the mold
https://scontent-lhr3-1.xx.fbcdn.net/t31.0-8/13055911_10206033234464296_1495349813495076963_o.jpg

forgot: you can add up to 25% paraffin wax without it changing the colour of the wax, it will help the crystal structure during cooling to help stop cracking, you can advance cooling if mixing in paraffin especially a microcrystalline wax

 

[tonyofarr]

I agree with Muswell Metro, a honey warming cabinet works really well, ours has more than paid for itself over the last twenty years. I never add any paraffin wax because our customers always want 100% beeswax. When we get candles cracking it is always in glass moulds and is because the wax is too hot, or they are cooling too quickly, which is why we use the warming cabinet especially in the summer when we don't want the heating on.

The silicon moulds are brilliant for 'textured' candles such as honeycomb, Christmas trees etc, but the ordinary straight silicon moulds are not that great because the candles lack lustre and even polishing them does not work that well, maybe someone else has a solution for that.

 

[chrisb]

if you haven't got a warming cabinet you have an oven

 

[Mandeville]

Thanks everyone for all the excellent tips. chrisb's picture is exactly what I'm aiming for.

I'll definitely try cooling the wax a bit before pouring it - I think I probably have been getting it too hot.

For this particular batch, I really want 100% beeswax, so adding anything else will be a last resort, but I'll use it if I can't solve the prob any other way.

The honey warming cabinet suggestion is brilliant, but my homemade one may not accommodate the mould, it was built for honey jars only, but it may be reconfigurable. If not, the oven could work.

Any thoughts on whether there's any advantage to pouring it in small quantities rather than doing it all in one go? I want the final height to be 5-6 inches, so I could do it in 3 steps. If so, what stage should each layer be at when I add the next?

And one other question (for now anyway!) - what's the best way of cleaning the polycarbonate mould? The usual hot water with washing soda technique?

 

[chrisb]

do not do it in two pours you will create a stress point,
6" is easy the one in the photo is 18" and 3" diameter
make sure you melt enough wax, silly to say but surprising how many dont and get stuck.
wick the mold up, pour the candle in 1 pour wax should be at about 65c - 70c above 80c and your cooking it to far bellow it wont flow proper
once the top ( which is the bottom of candle when molding ) has skinned slightly you need to make to vent holes, thick knitting needle or anything like that. gently push through top skin aiming towards the wick and to about half candle depth 2 holes one 90 deg to the other. keep these holes clear
for the second pour once the waxstarts to loose its softness bring remaining wax to temperature at just above the temp of the wax for the first pour then pour into one of the holes until center void is filled and to the level of the first pour. keep it wrapped and away you go.

and yes warm water and washing up liquid carefull you do not scratch the mold

 

[Mandeville]

Thanks Chris, that's really helpful.

Followed your instructions and got one cooling now - fingers crossed.

 

[chrisb]

brilliant
give them a day to cool, if you get any sticking in the mold pop it all in the fridge for 5 min and try again, it contracts them enough o release from the mold

 

[Mandeville]

It's worked perfectly, dropped out of the mould easily and no (visible) cracks - thank you so much for the advice.

All I have to do now is get the wicking right and I'm ready to go into production.

One final (maybe) question - any tips on good ways of tidying up the bottom surface of the candle?

 

[B+.]

What an inventive lot you are!
I must confess that I know very little about wax processing and have certainly learned something here.
Thank you

 

[B+.]

One final (maybe) question - any tips on good ways of tidying up the bottom surface of the candle?

Oh...I know this one....
use a warm hotplate to melt the bottom flat. There are some devices that melt ridges into the bottom, or round it off (depending upon what holder you have) in some catalogues

This link shows you what I mean https://youtu.be/G8OOoqZKJUY?t=8m30s

 

[chrisb]

Oh...I know this one....
use a warm hotplate to melt the bottom flat. There are some devices that melt ridges into the bottom, or round it off (depending upon what holder you have) in some catalogues

This link shows you what I mean https://youtu.be/G8OOoqZKJUY?t=8m30s

B+ got it in one, a hot plate, snip base of wick just bellow base !
if a bit uncertain with heat a flat cheese grater fine side gentle strokes

 

[chrisb]

It's worked perfectly, dropped out of the mould easily and no (visible) cracks - thank you so much for the advice.

All I have to do now is get the wicking right and I'm ready to go into production.

One final (maybe) question - any tips on good ways of tidying up the bottom surface of the candle?

brilliant