Intro: How to (and How Not To) Laser Cut Chocolate
I had a rather misguided desire to figure out how to laser cut chocolate well enough that you could build models out of it. And through many trials and tribulations, I finally figured out how to get reasonable results when laser cutting chocolate! Throughout this Instructable I'll go through the trials of laser cutting chocolate I went through until I finally came up with a workable solution, and then explain the process so that you can do it yourself.
For the final process, this is what I recommend you using:
- Dark Couverture Chocolate
- Wax Paper
And if you enjoy this tutorial, please consider voting for it in the Science of Cooking competition.
Step 1: Attempt 1 - Control
I started by just getting a bunch of different types of chocolate to have a baseline of how well each variety would cut. In the order of how well I expected them to cut, I got plain old Hershey's chocolate, white baking chocolate, 3 different types of regular baking chocolate ranging from milk up to dark, a bar of 100% cocoa, and then some really fancy chocolate.
The fancy chocolate is a couverture chocolate, which is a chocolate that has a high percentage of cocoa butter and can be tempered. I particularly wanted to try tempered chocolate because it has a higher melting temperature than regular chocolate, which I thought would be particularly useful in preventing the chocolate from melting when being laser cut.
My original goal was to try to cut chocolate that was 3mm thick. This would be a bit of a sweet spot, because there are a ton of projects that you can find online for 3mm thick materials, and you could potentially just directly use them with the chocolate.
So I started by laser cutting and assembling a mold that would help me create flat 3mm sheets of chocolate.
To get the chocolate into the molds, I microwaved all but the tempered chocolate until melted, then poured them into the molds, and flattened the chocolate using a pallet knife.
To temper the chocolate, I first used the seeding method. To start I heated up a pan with water on low heat with the chocolate over it in a bowl. You want to gradually heat up the chocolate to 45-50 degrees Celsius so that the crystal structure of the chocolate is entirely broken down, then cool down the chocolate using chocolate that is already tempered, which seeds the chocolate, and adds back in the crystal structure that we want. Once the chocolate was cooled to between 31-32 degrees Celsius, it is ready to be used.
I made a larger batch of tempered chocolate than the others because it's easier to temper larger amounts of chocolate since the temperature will not fluctuate as much. You want to work fast because tempered chocolate hardens very quickly. I didn't quite work fast enough to completely flatten all of the chocolate sheets that I made... But it will be fine for testing purposes.
Step 2: Attempt 1 - Laser Cutting and Assembly
And now for the laser cutting!
Using the extra large batch of tempered chocolate that I made, I started cutting squares at varying power and speeds until the cuts were successfully going through
My thinking during testing was that we wanted to cut as fast as possible in order to minimize the amount of time that the heat had to spread through the chocolate. And this should shrink the kerf of the laser (which is the width of the material being cut off)
I started getting some amount of success when I used multiple cuts instead of just one. And with this technique I decided to try cutting a little house and assembling it with the tempered chocolate.
I tried a couple of the different chocolates as well, including the white chocolate, but found that even though it cut through, it was too soft to handle and assemble.
So after all that work setting up the samples, I was really only going to look at the dark baking chocolate and tempered chocolate, which were the ones that cut the best.
Then I went about trying to assemble the house. The edges where the laser cut were not clean, so I had to use an exacto-knife to scrape off the extra chocolate. This jouse was the tempered chocolate, and I was hoping that it would handle well, but I found it starting to melt in my hands when working with it, though I did have warm lights on in the room.
Tempered chocolate shouldn't melt in your hands at room temperature, so my best guess at what happened is that the laser cutting brought the edges of the chocolate out of temper, making the edges more susceptible to melting in your hand.
We've got some room for improvement.
Step 3: Attempt 2 - Thinner Sheets
Now I'll run quickly through my other unsuccessful attempts before finally coming up with the reasonably workable solution that I found.
For my second attempt I simply tried to make the chocolate thinner. This time I used a mold that was 1.5 mm thick instead of 3. And while it did cut through better, I found it more fragile and susceptible to melting when handling it.
During assembly, this time I used a syringe with melted chocolate to help glue the house together. All in all, an improvement from before, but the thin chocolate was even harder to handle, and the results still weren't great, so on to the next idea.
Step 4: Attempt 3 - No Mold
For my 3rd attempt I tried making sheets of chocolate without a mold. Since laser cutting the molds was a bit of hassle, I wanted to see if the quality was comparable if I just tried to flatten the melted chocolate between two sheets of wax paper.
I found that doing this had the advantage of holding the chocolate "in shape" when the laser cutter cut through it; it basically helped keep the melted chocolate from deforming. The wax paper also protected the chocolate from directly contacting any surfaces of the laser cutter. So while I'd still hesitate to call this process food safe, at least this makes it "safer".
I also moved from the house model to a miniature plane model. I found that there was some variation in thickness in the material, but it didn't affect the model as badly as I feared.
So while method didn't improve the cutting quality, it didn't seem to make it any worse either. I call that a win, and decided to not use molds for the rest of my attempts.
Step 5: Attempt 4 - Larger Model
During my 4th attempt, I found a much easier way to temper chocolate if you are using chocolate that is already tempered. For this method all you need to do is gradually microwave the chocolate until all of the chunks are just melted, and then you can reshape it into flat sheets.
For my 4th attempt, I tried a larger model. The fine details were problematic with my other attempts, so I thought that scaling it up might help. This time I chose a model dinosaur.
Initial signs were promising. The general outlines of the pieces turned out pretty well. The main problem I had here was that the joints where the pieces were supposed to connect were not cutting well. It looked like even though I was doing multiple passes, the chocolate was still flowing back into the portion that I was trying to cut, and welding it back together so that when I went to pop out the cut portions, it would break the piece that I was trying to remove.
Step 6: Attempt 5 - Multiple Outlines
For my 5th attempt I tried to address the joint problem by cutting multiple outlines. I was hoping that removing more material would reduce the amount of chocolate that could flow back into the cuts that I was making.
Unfortunately, this didn't end helping around the joints. The chocolate still seemed to flow back into some of the joints.
Step 7: Attempt 6 - Thickener
For my 6th attempt,
I finally pulled out the nuclear option; adding a thickener to the chocolate. Through my testing, I found that the baking chocolate cut slightly better than the tempered chocolate, while the tempered chocolate was slightly easier to work with when assembling because it didn't melt as easily. Baking chocolate already has a thickener in it, so I decided to test what the minimum amount of thickener I needed to add to get a clean cut, and then try that with the tempered chocolate.
To test adding a thickener to the chocolate, I added starch in amounts ranging from a 1/4 teaspoon up to 4 teaspoons per 50 grams of chocolate.
Once cooled, I laser cut the pieces to see at what point the quality started improving. And it was during testing that I finally stumbled upon the solution that I was looking for! I found that instead of doing multiple cuts quickly, I got cleaner cuts by cutting slowly. This was counter-intuitive to what I originally thought, and I believe this works best for two reasons:
- By cutting slowly, the laser is burning the edges of the chocolate/starch mix, which causes the burned edges to harden, and prevents chocolate from flowing back into the cut
- Any chocolate that immediately flows back into the cut will be pushed back out by the laser
That’s my best guess why it works. But the important part is that it does!
Armed with this knowledge, I was ready to start my final attempt!
Step 8: Attempt 7 - Final Process
During testing I found that the minimum thickener that got clean cuts was 1 teaspoon per 50 grams of chocolate, and when laser cutting, the settings I used for my 50 W laser cutter were 5 mm/s at 20% power.
To assemble the chocolate dinosaur, I moved to the garage because it was cooler. I originally used a syringe with chocolate to help weld the pieces together, but found that the chocolate was cooling off too fast in the syringe, so I switched over to a toothpick instead.
It was a pretty stressful process, but I made it to the end with a complete chocolate dinosaur… Until it fell over.
Now that I had experience assembling it, I decided to try it one more time, and see if I could get it to last longer than 10 seconds...
During my first attempt when I assembled the legs, I didn't widen the stance very well, and so it wasn't very stable. I made sure to fix that this time.
This time I made the model 25% smaller because I originally made the joints of the dinsoaur for 3mm thick material, but found that the chocolate sheets that I made had a tendency to be about to 1.5-2.5 mm thick, so I could afford to shrink it a bit, and I also thought that a smaller model would hold up better under its weight.
The second round went quite a bit smoother, though I found that the smaller model was more fragile, so shrinking it didn't actually help me.
In the final stages of assembling it, I had one of the legs break on me. Instead of starting over, I decided to try to weld it back together using chocolate, and it actually worked pretty well.
This dinosaur did break for me about 10 minutes later because it also fell over, sadly not while being recorded. So if someone else were trying to make it, I would recommend making a chocolate base for it, so that it won't tip over by itself.
I could of tried one more time, but decided that two attempts was enough, and I wasn't going to learn much more from trying again.
Step 9: What Did We Learn?
So what did we learn?
When preparing the file that you will cut:
- Be aware that there is a limit to how small you can cut pieces. The smaller the piece, the less detail you will be able to cut, and more of the piece will be out of temper (which means it will be harder to work with when assembling because it will have a lower melting temp). The smaller parts of the dinosaur model that I cut were about the limit that I could work with any reliability at all.
- Be aware of lines that are close to each other, as heat from the laser will melt an area, and can affect how the other line(s) will cut. For example, the teeth in the mouth of the dinosaur were pretty melted because of all of the lines in close proximity.
When preparing the chocolate to be cut:
- Wax paper works great for creating the sheets of chocolate, as it helps you flatten it, and also serves as a (decent) protective buffer when laser cutting. It also helps hold in the shape of the chocolate when laser cutting. But it can be a pain to peel off.
- Tempering the chocolate doesn't help when laser cutting but it does help when you handle it afterwards. The easiest way I found to create sheets of tempered chocolate, was to have chocolate chunks that are already tempered, and then microwaving it until just melted, which will keep it in temper (you can find basic instructions in the steps above or better instructions elsewhere online).
- Adding a thickener like starch is basically necessary for laser cutting. This increases the viscosity of the chocolate and will help produce cleaner cuts. I found that 1 teaspoon of starch per 50 grams of chocolate was about the minimum that produced clean cuts for me.
- In general, the darker the chocolate, the better it will naturally cut.
When laser cutting the chocolate
- Somewhat counter-intuitively, I found that cutting slow worked better than cutting fast. I believe this worked because it burns the edges of the chocolate/starch mix, preventing flow, and any flow that does get into the cut is pushed out because the laser was moving slow enough.
The settings I used for my 50 W laser cutter were 5 mm/s at 20% power.
- The edges are out of temper, and so needs to be treated with care (it will have a tendency to melt in your hands). Assembling in a cold environment helps with this.
- You can use melted chocolate to help weld pieces together. And if a piece breaks, you can try to weld it back together using melted chocolate.
And a final important question that should be answered. How does it taste? If you're eating along the edge, you can taste the burned parts, and it reminds me of burnt chocolate chip cookies. So while not wholly unpleasant, laser cutting does negatively affect the taste of parts of the chocolate.
So does it take a lot of effort? Definitely. Will the results be perfect? Probably not. Is it worth doing? That's up to you. But now you know how!
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