Becky and I have talked about smoking our own food for some time and I’ve finally got around to making our words into reality and built our own cold smoker. It took a fair bit of research and a modicum of DIY skill but I’m going to attempt to boil it down into easy steps if any of our readers fancy giving it a go.
For the uneducated, the difference between cold smoking and hot smoking is that with cold smoking the fuel is merely smouldering, generating smoke but not (much) heat, so the food just gets smoky but doesn’t cook, while in a hot smoker the food is cooking as well as being smoked. Since we wanted to smoke our own bacon and ham for cooking later on, the cold smoker was the obvious choice for us.
The basic requirements for a cold smoker are:
1. Something to burn sawdust in (and of course, some sawdust)
2. Something to light the fuel
3. Something to contain the smoke and the food you’re smoking
4. Ventilation (a way for air to come in and a way for smoke to get out)
5. Something to sit the food on or hang it off
6. Something to spread the smoke evenly around the smoking chamber (though from what I can tell this is an optional nice-to-have)
7. A thermometer, so you can make sure you’re not inadvertantly hot-smoking your food.
1. The burner and the fuel
For cold smoking, you need fairly fine woodchip, so that it can smoulder but not burn. I’m told that you can use shavings from a wood plane, but so far haven’t tried this. At the moment we’re using specially made sawdust, which is very fine indeed – dust and very tiny shreds of wood – which we purchased online. I’ll be trying the wood plane approach in due course and will report back how that goes.
You should give some thought to what kind of wood you want. Different woods work best with different foods. I won’t cover this in detail here as it’s easily available elsewhere, but I understand that oak is a very versatile wood – we used it for our bacon – and applewood goes well with cheese and ham, so that’s what we used for those. But there are dozens of usable wood-types, with subtley different flavours. One thing to avoid if you are producing your own woodchip is resinous wood, like pine – I do not know why, but it is not appropriate for smoking.
I found burning the wood a bit more challenging than I’d hoped. Don’t get me wrong – I succeeded in getting a 24-hour burn without the smoke going out, which is basically good enough to smoke more-or-less anything. But there were various things about it which weren’t quite satisfactory, as I’ll describe below.
My research indicated that you can burn the sawdust in pretty much any metal container. I’d heard of people using tin cans, specially designed shop-bought mesh trays (about £50 for a large one), or a metal tray such as an old roasting tin. This last approach is what I’ve used.
The simplest configuration is to put your sawdust in a heap and set light to it in one corner. The smouldering, burning section of the sawdust will gradually pass through the heap and generate smoke as it goes. However this is obviously a bit less controlled than you ideally want.
I have heard of people using a cylindrical burner, filled with sawdust which is then lit at the top and burns downward, like a candle. That’s one way to control your burn, but obviously not open to those of us using a roasting tin! Instead, I decided to try and copy burners I had seen online which arranged the sawdust into a long thin line, like a fuse, which then zig-zagged back and forth across the burner, separated by little walls to stop the burn spreading out of control.
My attempts to do this met with mixed success. The simplest arrangement, which saw me heap the sawdust against three walls of the roasting tin, forming a U-shaped fuse (no walls) worked well in that it burned steadily, did not tend to go out, and produced temperatures between 15 and 25 C, which is about right. However it was very fuel-hungry, getting through a full kilogram of sawdust to produce 24 hours of smoke.
The alternative approach, which was to build walls out of tin foil and then use these to create a zig-zag channel, enabled me to put much more sawdust in the tin (because the walls meant I could put the lines of sawdust much closer together without risk of the fire spreading between them). However, I struggled to keep the sawdust alight. I tried several configurations and each time the smoke would stop, sometimes after a few minutes, sometimes a few hours. But never long enough to give me confidence that it would keep burning through the night, which is what I was aiming for.
The bottom line is that I think I can do better than 1kg per 24-hour burn; the shop-bought burners manage 16 hours with 300g, so my U-shaped arrangement is terribly inefficient. But my attempts to improve on this have been pretty much unsuccessful. I have ideas involving using a mesh for the walls so air can flow more freely, or perhaps copying the cylindrical design mentioned in the link above. Watch this space.
2. Lighting the fuel
I did quite a bit of research before this project, and found a lot of differing advice on how to light your sawdust. A lot of people were talking about using a tea-light to get it started; that presumably works for shop-bought burners, which are made of a mesh through which the tea-light flame can easily pass, but it didn’t work for me at all. Another approach is to use a blow-torch, which seems to work fine. But in the end I settled on using a camping gas ring. I placed one corner of the burning tray over the gas ring, and after about 5 minutes on a low heat, the sawdust was blackened, smoking and sometimes even aflame (when it’s on fire, that’s definitely the time to stop, but ideally a bit before that). The gas ring has the advantage of being fairly stable and easy to just switch on and off, and it gets the tray nice and hot which I imagine helps to keep it alight at the start.
I saw some people talking about using methylated spirit to start the process off. I’m sure that makes it a bit easier, but I did not find it necessary at all, and as it’s one extra layer of hassle, I wouldn’t bother.
Next up: the smoking chamber.