Softening Candle Wax (lost wax casting)

Well, I made my first lost wax casting yesterday using lead, and a Plaster of Paris mold. It worked great, except that I didn't have enough lead. But, after searching on the great web, I realized that the wax I used was much harder than what the sculptors use. Why is this? Is it a different type of wax? I searched Google, and couldn't find anywhere to get the wax I needed. Maybe I typed in the wrong name. I don't know. I'd much rather use my own wax, as my mom has a stockpile of large-er sized candles that softened and deformed in the Florida sun. How would I soften it, other than heating it in water? Is that water method thing how they normally do it? I'm really into melting metal, and want to do more casting, so can someone help?

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callmeshane9 years ago
Here is a useful tip... FLASH dewaxing your investment moulds, means that the with the co-efficient of expansion (how much it expands with a specific rise in temperature), of WAB being much higher than the moulds, and for commercial reasons the moulds are made as thin as possible on the basis that material & time & the building up of coats of refractory, costs far more to make a thick TOUGH shell than it does thin, and commercially "viable thickness" THIN shell... It all comes down to HOW you dewax the shell... IF you heat the refractory shell - containing the wax, very slowly, the wax expands more than the shell around it does, and so commercially THIN shells can easially break or crack. But if you FLASH dewax the shells, - this means that place the hard and dry shell in to a very hot environment - such as a pressurised steam autoclave or a HOT (red heat) furnace, it has to do with the way the HEAT flows from the OUTSIDE of the shell into the center of the wax core The shell heats up very fast, and the surface of the wax pattern heats up and melts out (usually soaks into the refractory) - and this GAP allows the wax pattern inside the refractory shell to expand (and melt as it does so) without pressing the refractory shell - until it cracks. So this is how you (and the professional manufacturers) can use a very thin refractory shell. Also commercial investment casters (all sorts of very accurate and high quality parts) use a specific range of blended waxes, dyes and plastics (mixed into the blends). Depending upon your ambient or average room temperatures, and for startign off, for making a wax BLENDE that is malleable by hand, I'd be using about a 50/50 mix of bees wax and parafin wax.... Another idea is to keep your wax and pattern in a warm oven perhaps 30 - 40*C and periodically pulling it out for several minutes, out of every - say 5 or ten minutes in the oven.... Or working under a dimmable heat lamp... just to keep the pattern and where you are moulding it - a little bit warm.... Also the idea of a double boiler is NICE for melting wax, and when it's turned right down, it;'s good for keeping your about to be used wax warm. Another idea - a cheap version of the commercial version, is to use a light dimmer switch in line with a small soldering iron, and by keeping the soldering iron tip just above the melding point of the wax, you can use this to WELD your wax "fine bits" onto the pattern, such as your runners and risers, and or to add or remove surface details to the pattern. Cheers Shane
John Smith (author)  callmeshane9 years ago
Hey, thanks again for a great response. I really appreciate it. Anyway, that's what I thought for the wax, now all I have to do is get some beeswax...and before that, money.
How much wax do you need? Try to talk you mother into buying you a bag of those little red BabyBel cheeses. The wax around those is very soft - seems softer even than regular bees wax.

Melt it down, filter, and add about the same mount of candle wax. The red color will also make it easier to see details of your wax sculpture.
John Smith (author)  Patrik9 years ago
Haha, that was MY idea! I have been collecting it for that purpose! I'll see if I can get her to get some more...it's a good thing she likes the Gouda cheese flavor...
jtobako9 years ago
Try "casting wax" or "carving wax" or my heap for some recipes.

John Smith (author)  jtobako9 years ago
Ok, thanks, I'll check there.
Kiteman9 years ago
Many years ago, I was taught to sculpt a head by Bernard Pearson, The Cunning Artificer. The wax we used was "proper" sculpting wax - it was as easy to work as plasticine, but it wasn't sticky, and could hold much finer details.

As I recall, it was much more malleable than candle wax, but did not soften in the heat of my hand.

Apparently, a lower melting point means that finer details can be sculpted, because the molten wax is more fluid, and will run out of finer spaces when the mould is heated.
Do you need the wax softer? Are you trying to sculpt with it? Cheers, Pat. Pending
John Smith (author)  Patrick Pending9 years ago
Yes, for lost wax casting, where I need a model of the finished product, in wax. It is then dipped in plaster of Paris, then the wax is melted out, leaving a perfect cavity in the plaster, the shape of the wax sculpture. Then, molten metal is poured in that cavity, and left to solidify. After that, the plaster is chipped away, leaving a metal copy of the original wax model. It is not as complicated as it may sound. Anyway, I thought that they used extra soft special wax, because it would be easier to mold. The reason I thought that is because that my wax will break at room temperature, not mold and bend.
I have done lost wax casting myself using paraffin wax, but I wasn't sculpting it . Apparently, you can soften your candle wax by adding beeswax to it (60% paraffin wax to 40% beeswax). While sculpting work in a warm room, and place an angle-poise lamp close to your work to keep the wax warm and malleable. Cheers, Pat. Pending
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