Candle Molds using PLA?

[Ben Latz]

Could I pour hot wax (125F) into a printed mold (PLA) without problem? I'm not sure if it will stick, but it would be great to be able to print molds for candles. Any ideas/comments would be much appreciated. Thanks

- Ben

[Shawn]

I did this recently with an ABS mold and ran into troubles. Overall the
end product came out fairly well (darth vader keychain done as a candle
instead), but not until some issues were worked out. I built the model
with 2 shells and 20% fill. It turns out there were some holes in the
negative space for the wax. So, I now have a brick of wax surrounded by
plastic which happens to give the right outcome now. Needless to say,
my first "pour" didn't include enough wax.

Also, we ended up having to do a light coating of veggie oil on the
negative space so the part would come out. The first two castings were
really hard to remove.

I doubt you'd have any problems with the heat for a PLA mold, but the
issues I just described are likely to come to light. I'd recommend a
higher fill % (maybe 100%), and/or more shells to help minimize this.
Or better yet, print a positive, then use the reusable resin based
materials to create your mold. I think you'll have less hassles with
that in the long run.

My thoughts.

Shawn

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[sciencemike]

Use more than 3-4 layers for walls when you you want to be impervious to liquids. Thats the rule I have been using, but a hot liquid that bonds with PLA, i would do 100% infill as the hot wax penetrates the layers.

Also instead of using veggie oil on your molds wich will go rancid and smell badly use http://www.candlewic.com/store/Product.aspx?q=c27,p204

Its a mold release, and it makes wax come right out of molds.

You could also try making a negative out of your part using rubber and then pour wax into that.