Filing Cabinet Hot/Cold smoker

Turn an old metal filing cabinet into a source of cheap gourmet grub.

Filing Cabinet Cold Smoker - Introduction

Salting and Smoking food was prior to refridgeration one of the major ways by which food was preserved. Whilst this need has gone, the techniques linger on, turning pork into bacon, salmon into smoked salmon, providing us with food that is ever lastingly popular or near the top of most gourmets list of favourite bites.

The trouble is that unless you have both the means and ability to buy from specialised outlets, the cured and smoked produce you buy today is of very dubious quality. Buy bacon from a supermarket and watch it shrink in a frying pan, emitting white gunk. The chance are your smoked salmon is of the farmed variety, flabby meat pumped with dyes and God knows what else?

You may think that there is no way to avoid this, that the processes involved in creating these foods are beyond the scope of the home consumer.

In fact though both curing and smoking are very very simple.

This project does not cover curing, but looks at creating a cold smoker out of a filing cabinet, which could also be used as a hot smoker, but as of this time I have not tried hot smoking.

Hot and Cold smoking deserve a little explanation at this point. Hot smoking will produce cooked produce ready to eat, cold smoking flavours and preserves produce, which then may well be eaten raw like smoked Salmon or may require cooking.

This article is instructions on the finished machine, but since I started almost from scratch it was a learning process, and you may find it useful reading to follow the development of the project on the River Cottage Forums. If you are interested in this project, then no doubt you will find plenty of other  things to interest you on the forums, so take a look anyway!

Building the filing cabinet cold smoker

First thing you need to do is get a filing cabinet. You are looking for a four drawer metal cabinet. These are always going cheap or free in the small ads. Mine cost me £15.00 which is really pretty expensive as these things tend to go, but I was impatient to get started. You are looking for a sturdy cabinet in fair condition. It should take two to lift it! If it doesn't is it some modern flimsy thing? You don't want that!

Here is mine with the drawers out.

Drifting a little out of construction order, but you will need the ability to heat from under the bottom of the cabinet. Normally sawdust and heat source will be in the bottom drawer. But our aim is to be able to cold smoke and if your charcoal is fierce you need to be able to remove it to under the cabinet.

However this would leave your sawdust three layers of metal (container, bottom of drawer, bottom of cabinet) away from the heat and this is too much, so a large hole needs to be cut in the bottom of the cabinet. A good jigsaw with a metal cutting blade, or an angle grinder makes short work of this. The hole will also provide an air inlet, and the bottom drawer should be ventilated as well. I did a couple of small grooves with an angle grinder. Fire needs oxygen, but we want smouldering and not a  blazing fire, so be conservative, cutting more holes is easier than filling them in.

To draw the smoke up we need a chimney effect, so we cut a hole in the top of the cabinet, a frying pan spatter guard stops the flies and light rain penetrating, and crude but effect a piece of wood holds this down and can be move to open/close the vent.

 Whilst we are on the subject of drawing the smoke up, we will have limited success with all the drawers intact. The top drawer and the third drawer down must have their bottoms removed. How you do this may well depend on the construction techniques used in your particular filing cabinet. My technique of brute force, chisels and hammers has little to recommend it.

The second drawer down needs to have holes drilled to diffuse the smoke. I think I need more in mine even now, but as said before drilling the holes is easier than filling them in.

The racks

We need to hold the food, I got luck, some racks from Morrisons were a perfect fit and some potato bakers from one of the cheapy stores add the means to hang things.

But hanging things means you have to use the second drawer as well as the first. On my filing cabinet a strut would get in the way. Hence the angle ginder comes inot play again, and liberal use of "I can't believe it's not nails" is a rough filler to prevent too much smoke escaping.

So how do you smoke?

Generally the wood you smoke with is hardwood sawdust/shavings, Oak or Beech for example. Getting hold of this may be problematic. If you can find a source, then it is effectively a waste to be disposed of, so it should not cost a lot. I have a couple of generous suppliers. You may want to contact sawmills, but be careful that it is untreated wood, and not contaminated with soft woods.

We need to create a smouldering smokey fire, so you do not want totally dried out sawdust. I think it is accurate to say, that you want sawdust that will need the encouragement of a separate heat source to keep on going.

What I am using is two large colinders, the top one takes the saw dust and is stacked on one with hot charcoal.About 1kg of charcoal is used for 10 hours smoking, and about 6 pints of sawdust may be consumed. Though this might be reduced with dampened sawdust.

Smoked Salmon Portions from Frozen

This has worked well for me, soak the salmon in brine for 2 hours. The brine is 1lb cooking salt to a gallon of water. Then lay on the rack and smoke for 10 hours.  This time includes downtime, when you find you need to attend to the sawdust. Generally this is about every hour or so. But damper sawdust and more charcoal may improve this.

For cold smoking you don't want the tempurature much above 85f and a thermometer is essential. If you are too hot, place the charcoal colinder under the cabinet.