Some people work it apart using an awl, like this Osborne 478 Scratch Awl (available on Amazon).
I believe @phyllsheng uses a coping saw sometimes. I've heard of people using hacksaws as well.
A good method should balance:
- Ease of splitting
- Minimization of waste
- Clean appearance
I like the saw approach, so I decided to search for one that makes the narrowest possible kerf.
The best I can find so far is this dozuki by Suizan:
Dozuki is a kind of Japanese woodworking saw with a thin blade supported by a stiffening spine. I think it's often used to cut delicate joints. The teeth seem made for cross cutting which is probably good for this application, but it probably doesn't matter since tea is comparatively soft material.
According to the manufacturer, this one's 8" (20cm) blade is 0.008" (0.20mm) thick and cuts a 0.012" (0.30mm) kerf. Actually, I measured 0.18mm blade thickness:
Here are my results with this new tool. It's my first time using it.
Take a look at that narrow kerf (note that the cake is about 90% sawed through). It's almost like it was cleaved by a water jet
The cutting took about 5 minutes, but a lot of that time was spent getting used to the tool and trying to find a better surface to cut on. I had to flip it over and tap out the sawdust several times. I think it'll take me a minute or two next time I have to split a cake.
I made this into a little experiment to see how much waste was generated. Here are the resulting fractions after sawing:
The original cake mass was 356.8g. After sawing, the resulting halves weighed 351.9g (98.6% of the original cake!). I also recovered 3.3g (0.9%) of what I'd call respectable debris. This is perfectly usable stuff (whole leaves or large fragments, not dust), and it was generated mostly by handling the cake during splitting. Next, I collected 1.1g (0.3%) of ultrafine sawdust. I'd consider this waste, but I guess you could brew it. Finally, 0.5g (0.1%) was lost to entropy.
Overall, 99.6% was recovered (98.6% in the halves!). I'm pretty satisfied with this method.
How do you guys split cakes?