Chocolate Mold Round 3

The syringes arrived so I gave the chocolate mold project another try. I also tried to do the cold water bath thing for tempering the chocolate. It didn't work.

Ideally I'd have a temperature controlled multi-color extrusion machine setup where I just put the molds under it and it precisely fills them. For now I'm taking a break from chocolate though.

Chocolate Mold Round 2

I bought a sheet of HDPE plastic (note: they are called sheets, not blocks, even though this 'sheet' is 1 inch thick) and milled out a bunch more mold positives.

Then I cast them with Smooth-Sil 940:

And then I spent all of this morning making a huge mess in my kitchen and burning myself repeatedly. Here are some very messy first tries:

Verdict: Pouring chocolate is a real pain.

What didn't work::

• Screw-top plastic squeeze bottles
• Plastic becomes softer when warm, tip clogs, then applying pressure just causes the cap to explode off the bottle
• White Ghiradelli chips burn before they melt. Cherry chips burn before they melt. Old candy melts burn before they melt.
• Ziploc piping bag
• You have to keep readjusting your grip as the bag empties--not enough fine control
• Improvised double boiler--didn't get as hot as I wanted and chocolate ended up solidifying in the wrong way (basically it only hardens in the fridge/freezer and it is too soft and pliable)
• Spoon -- not enough fine control
• Thick and tall mold walls--I didn't think about this, but the thicker and taller mold walls make it harder to release the chocolates without breakage. This means having to pour the chocolate fairly thick to make it strong enough to survive release.
• I can cut down the existing molds with a knife fairly easily
• I can get a new block of HDPE and mill everything again ($24 and a few hours sitting in front of the CNC)

What did work:

• Microwave method. Much cleaner, less moisture, you can reheat whenever.
• Syringes (oral syringes, plastic kind).
• The trick is to empty them then pump a few times between uses, to avoid having the tip clog. If there is a big enough hole left in the tip to allow suction of the liquid chocolate, then the hardened chocolate in the tube will be melted by the newly suctioned chocolate.
• Actual chocolate, and candy melts that aren't very old. These melt fine in the microwave.
• Tapping/dropping the mold repeatedly
• Rather than trying to put the chocolate in an even layer, it is possible to just put some in the center then repeatedly shake/drop the mold onto the countertop until it settles in a flat layer

What might help make the process better:

• Gloves, to avoid leaving melty fingerprints on the chocolate when demolding
• Better quality chocolate
• A brush or a toothpick for cleaning up details in the first pour
• A temperature controlled rig for keeping the chocolate ready for pouring (expensive, but probably very helpful)
• A candy thermometer for checking the temperature
• Cocoa butter/veggie oil/butter/coconut oil for the syringe (should make it a lot easier to pull the chocolate into the syringe)

So what's next? I was only able to obtain one syringe in stores today, so I went online and ordered a bunch more in various shapes and sizes. I've spent a lot of money on this project so far but I'd rather learn to do things right than to just get some mediocre results out cheaply and quickly. And I guess that reveals that the whole point of this project--not to create cool looking chocolates, but rather to learn about mold making.

Chocolate Mold Round 1

I finally did my first silicone pour. The first run I messed up by reading off the wrong set of instructions and mixing with the wrong ratio as a result. The second one worked, with only minor issues. These results are far from beautiful because in my rush to put out a few 'prototypes' I decided to try microwaving chocolate instead of double boiling. The microwaved chocolate was unevenly heated and ended up being hard to work with. Next time will look much better!

Things I have learned:

• The cured product seems very good--surprisingly durable and flexible.
• The process of pouring takes some finesse, but I'll post about that after the next few pours.
• The texture of the wood ultimately did transfer onto the silicone, but those fine details got lost on the chocolate step.
• The process of melting and pouring chocolate is not easy either. Each product behaves slightly differently as well. Though 'supported' on the package, microwaving is not a good method.
• A lot of the crappy candy melt stuff I bought tastes like crap. Big surprise. Pretty but disgusting in flavor. Good for practice I suppose.
• I designed this bar to be 3/8" thick in the body and 1/8" thick on the details (the raised scales). That's a pretty thick chocolate bar. I tried pouring one with a much thinner body but it cracked in the removal process.
• Ideally, I will find a way to melt the chocolate until it reaches as low a viscosity as possible. That will make the process faster and easier, and also make the chocolates a lot nicer looking.

I ordered a block of HDPE to mill my next positives. That will get rid of the wood grain issue. There should be enough material there to mill about 6 different positive blocks, so in addition to remaking this one, I will try a few more designs.

I will also give these a try with colored ice, to make 'stained glass' type window panes to put outside this winter. One advantage of Wisconsin is it is a great environment for ice and snow art. The weather will stay well below freezing for months at a time.

Happy holiday making!