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Cardboard Cold Smoker

Picture of Cardboard Cold Smoker

Being a long time fan of Alton Brown's, Good Eats, as well as long time fan of bacon. When I saw Alton's show about how to make bacon from scratch I was inspired to make it, as well as, lox (smoked salmon), and other tasty, cold smoked/cured foods. But this requires a cold smoker. There are a lot of “hot” smokers on Instructables, but I have not seen a 'cold' smoker. Since Alton ran through his version and there is not one on instructables I decided that I would make my own version and put it out there for others that wanted to try it as well. 

The main difference is the application of smoke without the application of heat. If you try and make bacon with a hot smoker you will render out the fat and cook the meat before you have the right level of smoke and you'll have a sloppy mess.

So, with some cardboard, hardware, spare parts, and a bit of time I made a functional cold smoker.

Important Note: It seems that uncooked, yet cured foods may be regarded as safe, as long as the preparation and sanitation directions are strictly followed. That said, any animal product that is uncooked could be hazardous for the young, elderly, and those with compromised immune systems.

 
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Step 1: Materials

What you need:

Items:
Large box. I used a 21"x21" x 30" box. (Hot box)
Small cabinet (Cold box)
Strip foam window sealer.
Electric hot plate
10" iron skillet
9" Al pie pan
Smoking chips, (Hickory, mesquite, etc)
Long Al dryer exhaust. I got 20' but that may be overkill. Don't use the plastic ones.
Dryer exhaust adapter
Hose clamp for adapter
Computer fan (12v, 5v)
Power supply for fan, matching voltage
Extension cord
1" Pipe U bolt (2)
'S' hook

Tools:
Drill bit for making holes in cabinet. I used 25/64" but anything in the ballpark is fine.
Clear box tape
Box knife, or something thin and sharp for cutting the cardboard (Hot box)
Hole saw, to make the large hole in the cabinet (Cold box)
Dremel, to clean up large hole

Consumables:
Smoking chips (Hickory, Mesquite, etc)
Pork Belly
Salmon
Anything you want to smoke



Step 2: Hot Box

Picture of Hot Box
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Assemble box. Make sure to tape all open edges completely to seal it as much as possible.

Cut an access door in the front bottom of the box. I made a door that was 12"x8" but you can use whatever allows access for the hot plate skillet combo. i.e. on top of each other as one unit. It's easier to slide the whole thing in than trying to stack them once in the box.

The door should hold shut just from the edge friction. This is why you use a sharp thin blade. If you use scissors or a wider blade the door may not hold shut on it's own.

Temporarily hook up the fan so you can see which side is the blowing side. Since this is a positive pressure box you will want the fan to blow into the box. 

In the lower back corner of the box trace the outline of the fan. Then cut open another 3 sided access door just a little bit smaller than the outline you traced. 

Press the door in so the flap is on the inside of the box. Then wedge the fan into the opening. It should hold on it's own. Make sure the fan is blowing into the box and your power cable is outside of the box.

Using the box tape seal the fan opening from the outside of the box.

Trace the outline of the hose in the upper back corner of the box from the outside. Cut this open just a little bit smaller than the trace line. This will allow you to thread the hose into the box and get a good seal without having to use any tape.


Step 3: Cold Side

 Using the small side of the dryer vent adapter trace a round hole in the lower back of the cabinet (cold box).

Using a hole saw or cutter cut a round hole about 1/8" smaller than what you traced. This will allow you to press fit the adapter into the hole without having to anchor it in. if the hole is a little too small open it up a little at a time with a dremel tool by shaving the edges slightly. The adapter should hold in the hole tightly.


Apply the foam strip seal to all edges of the door where it contacts the body of the cabinet. This should give a better seal to the box and only allow the smoke to flow where we want it. Instead of leaking out everywhere.

Find the center of the top of the cabinet and drill two holes the size of the Ubolt. Using both sets of backer plates and nuts from the two Ubolts securely anchor the Ubolt to the ceiling of the cabinet.

Once you have the Ubolt secured you can hang your 'S' hook

Using a large drill bit make a number of holes in the ceiling of the cabinet. From trial and error I found that six holes of 25/64" gave enough flow to match how much the fan pushed. Start with 1/4" and work your way up and see what works for you.

You are done with the Cold side

Step 4: The Set up

Picture of The Set up
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Since we are dealing with heat and cardboard I would suggest that this is done on a concrete slab outside. I would also recommend having a kitchen fire extinguisher close at hand. i've never had a problem, but just in case.

Place the hot box where you can get an extension cord to it. Then place the cold box somewhere in the vicinity. 


Stretch out the hose as much as you physically can without stressing it. If you pull really hard on it you may rip the Al (it's just a coil of wire wrapped in Aluminum foil) and then you'll need a new hose. Once you figure out the path you want the hose to travel, make sure it's supported and secured so it won't move. When you are smoking you'll be smoking for at least 6 hrs and probably much longer, so make sure the wind will not disrupt your setup.

Using the hose clamp at the far end of the hose attach it to the large side of the adapter than is already installed in the cold box.

To power the fan I used an old car battery that I had around. I hooked it up to a small solar panel during the day and it would run the smoker all night with no problem. You don't need a car battery, I just had a source of 'free' energy, so I used it. The fan uses 0.15A @ 12V so almost anything can power it. You can use a regular AC adapter or a set of alkaline batteries. As long as the voltage from the power source matches what is on your fan and the amperage of the supply equals or exceeds that of the fan.

You are now ready to smoke.

Step 5: Smoking

Check the weather. Make sure it's not going to rain. Also make sure that it is cool outside. Like 60F or less at night. When smoking at night you don't have to worry about the sun baking your stuff. This is cold smoking after all. Also, it's quite easy to detect leaks in your system at night with a flashlight looking for smoke.

Open up the front access door and slide in your hot plate, skillet, assembly with the wood already loaded. You want just a single layer of wood in the skillet. Pretty much only the wood touching the hot iron will smolder. 

Set the plate to high for about 5-10 min. This should get the skillet heating up pretty quickly and allow the smoke to begin. After this set it back to medium to get a sustained smoke. You'll have to play with the setting to figure out what works for your hot plate. Close the access door allowing the hot plate cord to stick out so you can attach it to the extension cord. Make sure the extension cord is rated for the maximum amperage that the hot plate can draw.


At this point add your cured pork, salmon, or whatever it is that you want to smoke to the cold box. I used a set of cheap metal skewers that I bent into hooks to hold the meat. You want the cheap ones because they are very easy to bend by hand.

Allow your item to smoke for at least 6 hours, overnight or however long you like. The smoke that this puts out is milder than a hot smoke and you will not see a black crust on the outside. However, it will darken some as well as dry out the surface a little bit. 

While smoking, check on the wood every few hours and make sure it's still smoking. If it's stopped pull out your pan, with an oven mitt dump the spent wood into a fireproof container and refill with fresh wood. 

Note: This smoker does not cook your food no matter how long you smoke it for. So if you are making bacon from a pork belly that you brined and cured, you will need to cook it just like you would with store bought bacon. 

If there is interest, I can post other instructables on making the bacon or the lox.

ptabakaru11 month ago

this is great...you could smoke cheese, and other foods that hot smoking could harm.

ray.baldonade8 months ago
Put the tubing in a kiddie pool. That will cool the smoke.
kfurr1 year ago
Your instructables are awesome! Any chance that bacon recipe is posted as well?
Phoghat1 year ago
Alton is god. Built one of these when I lived in NY, now I'm in Mexico and they have no idea what real bacon tastes like
lvnfld2 years ago
Excellent! We are making this soon to smoke our homegrown bacon. Thanks for a great turorial!
911no5 years ago
Awesome job!
runfromnuke5 years ago
 It's like a hookah in reverse!!!
galenorama5 years ago
What temperature is the smoke in the cold box? I was just wondering how much heat is lost through the tube.
sandds (author)  galenorama5 years ago
The temperature in the 'cold' box is ambient. By the time the smoke has made it through the duct work it has lost all heat and is whatever the outside temperature is.

I will normally smoke after dark on a cool night. I like doing it when it's under 60F outside. Then there's no question that it will be too warm. 

When it starts heating up (I'm in Texas) I'll probably need to find another way to keep it cool. But for right now it seems to work great. 

Maybe running the duct work through a large cooler packed with ice or modifying a dorm fridge element to place inside the cool box. If I do either of these I'll update the instructable with a 'High ambient temperature' version.
mkeith545 years ago
Go ahead and post  your curing recipes for the bacon and the way you do the Lox.  Great job BTW!
sandds (author)  mkeith545 years ago
 Went ahead and did another batch of my Lox. Here's the link.

Homemade Lox
keng5 years ago
oh, man...I thought the pic of the skillet was you cooking the bacon 80)))))
sandds (author)  keng5 years ago
 I added a pic of the bacon for your viewing pleasure.