Rocketstove: Making one from metal Olive oil container

For the last few months I have have comments turned off. There was a lot to say and I didn’t want distraction. But don’t think that meant I wasn’t listening to you. I pay attention to what people read and what search terms lead them here.

Rocket stoves have been a popular search item so its time to give you even more information.

I’m going to make one. I’m starting with a 13kg Olive oil can and I’ll have photos for all the relevant steps and a boil time test.

13 Kg olive oil can.  31 pounds in weight

The starting material a large Olive oil can. restaurants and other food businesses throw these away quite regularly, so that’s a good place to start looking if you don’t usually buy oil in this size container.

It’s convenient that there is a large round hole in the center of the top so I wont need to cut one there. Somewhere in the purple band is where I will cut a hole for the pipe which will be the elbow bend pipe.

There is a small handle on the front which i will probably keep as it will be useful for carrying the stove if I need to move it. i think the handle will be better at the front rather than the back as it will stop the ashes falling out for the bottom of the elbow.


The next step will be using sand paper to remove the paint from the can. If the paint is left on the can, it will burn and produce unpleasant and possibly toxic fumes.


<more to come>

Scrambag: folding pruning saw

Apart from the obvious intended use of pruning trees, the compact folding pruning saw allows you to collect small branches easily.

A saw is safer to use that a axe or heavy knife in cutting wood. One of the most common sources of dry wood in a forest is dead-fall.

Dead-fall is dead or broken branches fallen to the ground, and are often very dry and difficult to cut will axes as the will act like a spring when hit.

Sometimes dead-fall is a branch upside down and very dry, because of this it makes excellent fire wood or construction material.

The saw can elegantly cut of the exact pieces you want and even help you create items form the wood with precise cut lengths and flat ends of wood.

The saw is also very light compared to a small axe and very small, about the size of a small axe handle.

Folding pruning saw, compact and allows straight cuts in wood with little effort.


Price about $10 for average quality.

Available from hardware stores and gardening supply stores.

Fire: Swedish fire torch

This is a really neat technique of conserving wood and getting a fire going fast and making a stable cooking platform. You will need an axe and a saw to shape the wood block, but it looks worth it.

I just had another thought, all the things are familiar but arranged in a different way and its suddenly so much better, what a concept.

Memes: One picture is worth a thousand words

I try to avoid using idioms and proverbs in writing. But sometimes an idiom is so true it is worth explaining.

One picture is worth a thousand words: means a single picture can convey so much meaning it replaces the need for ( is worth ) a thousand words.

Sometimes a single image or diagram will give the right reader so much information.

I hope this picture is conveys a lot of meaning to you.

A society built on cheap fossil fuel, this is what that society becomes.

This image is a remix of other internet memes, feel free to remix as I have done.

Soap: how to make it

So after explaining how soap works and why washing in water alone will only remove some things from your clothes or yourself, lets look at how to make soap.

Soap is made from a chemical process called saponification.
Oil plus alkali becomes soap.

Depending on the type of oil an alkali used and how they are processed determines the type of soap produced.

The types of alkali

potassium (potash): these soaps tend to be liquid. Bracken ash

Sodium common soft soap. normal wood ash

calcium very hard soap. does not dissolve easily. mineral lime

the types of oils commonly used to make soap

SAP charts:

This chart tells you how much alkali to add for each unit weight of fat/oil.

So for Almond, Sweet oil you will need 0.136 grams of NaOH per gram of this Oil to make soap.

If you are using multiple oils do the same calculation for each oil as though it were a separate soap and then add up all the alkali needed and add to final mixture.

The specific gravity is the density of this Oil relative to water (water = 1.000)  hence anything less dense than water will float on water as almost all of these oils will do.

Soap making SAP chart part 3: Essential Oils ( EO )

During the process of soap making you will either have too much oil or too much alkali.

Too much oil will make the soap greasy and too much alkali will be very harsh on the skin or material washed.

It generally better to have too much oil slightly as a bit greasy is better than very corrosive.

If you can do the numbers have 4-10% less lye than oil for optimal results.


Glycerine is a component of fatty acids and as the soap is produced the glycerine is produced.

too much glycerine will make the soap prone to converting to mush after its been left wet.

Try to experiment with removing the glycerine as the soap is made to get the right balance.

Production example:

cold process

Olive oil


measure out quantities carefully.

Lye will get hot as you make it from Sodium hydroxide granules a shatter proof glass container is a good idea.

Heat the oil/fat until it is liquid and about 50C-60C and a similar temperature to the lye solution.

mix in an appropriate container, plastic containers are good, don’t use aluminum pots as they will react with the lye.

use blender to mix. 5-6 minutes should be enough.

pour into tray or muffin molds to set.

cover witha towel to keep the soap warm as it sets.

After 24 hours take the soap out of the molds and leave them is a dry warm place to dry fully.

leave the bars to store for a few weeks to fully react all the lye.

test soap with pH strips or pool water pH kit

hot process




Technically oils are acidic and saponification is an acid base reaction and the soap is the ‘salt’ of that reaction

Disturbingly enough during world war I, some bodies left covered in lime became saponified and became soap from the action of the lime on the body fat.

Lye in form of Sodium hydroxide (NaOH)   can be purchased from some supermarkets as high purity beads in a small container. The high purity is useful in the very well measured cold  soap making process, as you will need to measure everything carefully.

Sodium hydroxide is normally used for clearing blocked drains, usually the drains are blocked with hair, soap scum, scale and fat, and int he case of fat the lye solution turns it to soap similar to the way we have just learned.

<more to come>

An excel based calculator for soap making


Basic rule of thumb:

1 part alkali ( by weight as a dry powder)

8 parts oil (by weight)

24 parts water (by weight)

Warming up the oil to the same temperature as the alkali (which will usually heat the water used to create it).


Soaps created from types of hydroxides

Sodium: a solid water soluble soap.

Potassium: a liquid water soluble soap.

Calcium: a solid mostly insoluble soap.

Lithium: a grease possibly with lubrication potential for machines.


Soap: How it works.

No matter what you do you are going to need to get clean.

Even if you are near a large water source and can wash there you will probably need soap. You will probably want to make soap eventually but before you do that well you need to understand how it works in order to do it well.

If you of your clothes were dirty and all the dirt was water soluble you could simply wash in water.

Salt is soluble in water so if you clothes were covered in salt you could just wash them in fresh water and the clothes would be clean.

However not all things are soluble in water, this is where soap comes in.


Almost all things are soluble in water or soluble in oil. In chemistry this is called non-polar and polar.

Water happens to be polar, which means able to form charged ions and other compounds like this will dissolve in it to some extent.

Oils are non-polar and don’t form ions easily and other non polar substances will dissolve in it to some extent.

Soap is a molecule which is both polar and non polar, having a polar  (oil soluble) component and a non-polar (water soluble) component.

It’s polar part is soluble in water it non polar part soluble in oils.

This allow you to use soap and water to wash out both water soluble and oil soluble material from an item.

Chemical structure diagram of a typical soap. The serrated line represents a chain of -CH2- units with a -CH3 at the end.

The soap allows the oil the ability to become partially dissolved in the water and spheres of oil with soap molecules embedded. These are called micelles

A micelle: oil sphere (green) with soap molecules (black) embedded in the surface giving it partial water solubility.

The process of micelle formation looks something like this:

Material (red and flat) and an oil droplet (green and rounded) forming in the presence of a soap, which allow the oil to form micelles, spheres suspended in the water (light blue).

Once the soap has liberated the oil from the material the soap/oil/water solution has to be removed, hence the need for the removal of the water with rinsing.

Rinsing allows more oil to be removed as all of  the initial oils might not have been removed. And excess soap will have more water to liberate the oil into.

Rinsing also allows anything already soluble in water to be removed. this is why a pre-rinse makes sense.

Rinsing also remove the excess soap which would otherwise attract dirt and oil and be an irritant.

Scram bag : Aluminium can stove

Aluminium can stove photograph

Firstly I know my North American readers will say you spelled it wrong, and while you may be right in that in your area its spelled aluminum. But  according to IUPAC its been officially Aluminium for the last 15 or so years.

We are of course talking about the 13th element on the periodic table witch has low density and low corrosion rate due to its propensity to form a protective oxide layer.

Aluminium will however corrode markedly if it is left in a salty environment such as a salt spray zone near an ocean or salty lake.

I should talk more extensively about Aluminium as a material at a later date.

We live in a throw away society where things are made to be used once and then destined to become land fill. The humble aluminium can is one such product.

However we can change the game and turn a low cost one use item into something much more useful and possibly life saving depending on the situation.

Water is of course essential for life, 3 days without water and its likely that you will be dead, close to dead, or if miraculously resuced at the last minute you may suffer from life long health effects.

Water is a great mobilizer of materials and living things some of these living things will be very harmful if you drink them.

If you find water of unknown quality you will need to be cautious.

Straining water even with a cotton shirt will remove most suspended material (dirt etc) but will not kill pathogens.

Boiling water after it has been strained will kill most pathogens and make water much safer to drink.

It not appropriate  or possible to make a fire in ever possible location you might be so a small cooker is a great option to have.

You could buy a propane/butane gas cooker but they are expensive by comparison require large gas canisters and are in themselves somewhat bulky and fragile.

So there is a niche for a cheap to make cheap to run cooker for boiling water or cooking food.

I made an awesome info-graphic and I’ll add it here. it may be better to download the image or open it is a separate window to see it in its full glory.

It described the manufacture of one of many designs of the aluminium can stove.


Aluminium can stove info graphic

Manufacture notes

1-Remove all of the paint from the can with sandpaper.

2-Empty the can.

3-Put holes into top section. (thumb tack or drill)

4-Cut out the circular section around the ring pull. (razor blade)

5-Cut into 3 sections. (razor blade or tin snips)

6-Cut center section.(razor blade or tin snips)

7-Flange out the  sharp edge bottom section slightly. (screwdriver shaft)

8-(optional) add glass wool between bottom and center sections.

9-Put top section inside bottom section.


this stove runs best from pure alcohol.
Pure alcohol is quite hard to obtain. the pureset from of alcohol is methylated spirts.
methylated spirts is about 96-99% Alcohol.
the rest (1 -4%) is made up other impurities (like methanol) so that is is toxic and/or unplesant to drink.
Methlyated spirits is quite cheap at about $2-3 per litre making this a very economical fuel.

pour fuel into the center section of the stove and light.
it may be easier to light the stove with a  match or piece of paper or dry grass rather than a lighter.

during day time the flame may be difficult to see.
once light the stove cannot be easily extinguised and the flame heat is not adjustable.
Different sotves produce different ammounts of heat and this may be a way of controlling heat.
multiple stoves may be used together to produce more heat.

Why is this item important.
It shows that useful things can be made from commonly available low cost items.
It introduces people to making things for themselves.
In many situations the ability to boil water to sterilise it maybe a life saving device.

The material
Aluminium does not readily corrode except for in a very salty environment.
(such as in the salt spray zone of beaches)
Aluminium may begin to corrode when place in contact with other metals for extended periods of time.
Aluminium melts at 660C, so its unlikely to melt during normal operation.
the thickness of Aluminium in cans makes them quite fragile.
A  sturdy container is recomended to prevent the stove being crushed in a backpack.

Alternative designs
there are many alternative designs to the can stove.
Each have their merits in terms of use and ease of construction.
For some people constructing these is a serious hobby.


Resources: wood ash

An important concept is life is to recognize resources and know what uses they can be put to.

There is not waste resource, just a wasted resource opportunity.

So what is in wood ash?

Wood ash makes up 0.34 to 1.8 percent of the weight of dry wood burnt in its production.

So 10kg of wood burnt will produce at least  34 grams of dry wood ash.

Wood ash is a good thermal insulator if it is kept dry, the small air pockets in it allow for it to have this insulating property, once it becomes damp or wet these air spaces collapse and do not return upon drying.

Wood ash is:

about 25-45 % Calcium Carbonate ( CaCO3)

About 10 % potash (K2CO3, KCl , K2SO4)

about 1% Phosphates (PO4¯³)

The temperature  and duration of the fire will influence the composition of the wood ash.

For example ta higher temperature will reduce the Calcium carbonate to Calcium oxide and make any resultant Lye more alkaline.

Wood ash is also used in odor control in composting especially if it has a high char content.

By adding water to Wood ash, Lye is produced, an alkaline mixture of Calcium and potassium hydroxides, thought the calcium salts will precipitate as it is not very soluble in alkaline solutions.

Lye is commonly use to reduce acidity in soils

Lye is also used in making  Soap

Lye can also be use to clean clothes directly by in doing so you are relying on the oil in the clothes being turned to soap during the washing process.

So it will be a lot slower and you will have to heat your water.

Materials: Stainless steel

Some people would like everything they posses to be made from natural materials, and there are good reasons for that thinking.

However there is one material that is really special for a lot of reasons.

Stainless steel.

It doesn’t rust, and therefore can last for several lifetimes.

The most common varieties are 18/8 and 18/10, what these numbers refer to is the composition of chromium and nickel respectively, that is mixed with the iron to create this steel.

Often these numbers are stamped into the item, and commonly with the terms ‘Rost Frei’ (rust free) or ‘INOX’ (Inoxidible).

If the steel rusts its not stainless steel, however some rust spots on stainless steel are the result of other ‘lesser’ steels coming into contact with stainless steel and leaving their rust on the unblemished surface.

Stainless steel also has anti-bacterial properties due to the chromium levels in the metal, this makes it an ideal material for items related to cooking and eating.

Because of its anti rust properties its good for marine related uses too.

Some basic modifications to common stainless steel items:

Stainless steel fork: A few bound (prongs out) onto the end of a stick: fishing spear tip.

Stainless steel forks bound onto stick to make a fishing spear.

Stainless steel knife: cheap abuse proof sharp knife? Get a standard  stainless steel butter knife and sharpen it with a disc grinder, the knife will be close to razor sharp and won’t rust or dull easily.

Stainless steel  spoon:  Arrow head!- hammer flat,  cut off sides to make a sharp ‘V’ point, sharpen edges, cut off excess tang (handle), done.

Normal stainless steel teaspoon showing how a broad head arrow point can be made from it.

Stainless steel  Pot,  boiled water distillation, from salty or dirty to pure distilled water, stainless steel make this possible, a normal pot would rust eventually.

If you come across items made from stainless steel, I suggest you start collecting them even if you see no immediate application for them. Think of them as good metal… forever.

If you think collecting stainless steel sounds a bit silly, read on…

I once talked to a guy who did some welding in the outback of Australia in a mining town where they were routinely extracting tons of lead, silver, and beryllium. He was an immigrant and thought of stainless steel as being superior to normal steel and slightly not vastly more expensive. He asked for some stainless steel from his employers to complete the welding work he was doing, every one gave him a reaction as though he had asked for platinum or gold. Feeling like he had stepped into a parallel universe, he was wondering why there was no Stainless steel anywhere. there was no other material he could have used to complete the work either.

Eventually one of his bosses quietly lured him away from the others and whispered  “Don’t tell anyone, but I’ve got some Stainless steel”.  He was later ( in secret ) given access to a secret locked box perhaps the size of 2 shoe boxes which had about 40 random pieces of stainless steel in flat and pipe form. Most were clearly off-cuts salvaged from other work. The guy took a few pieces that seemed useful to the task at hand, but didn’t have enough to complete the job.

Later on another one of his bosses (a close friend of the first boss) lead him aside and essentially repeated the same process giving him access to a different secret stash of stainless steel, where upon he had enough material to complete the job. Interestingly neither of the bosses knew of each others Stainless steel stashes, the paranoia and secrecy surrounding this scarce material was so intense. Once he had acquired all the Stainless steel, each of the bosses realized that he had got stainless steel form more than one local source. Later on both bosses approached him on separate occasions to be reassured their source of Stainless steel had not been revealed and to inquire about where the other Stainless steel parts had come from. A few times subsequent, several people on the work site quizzed him about his source of stainless steel, to which had had to remain evasive. He thought it might have been part of an elaborate practical joke, like stories of the giant carnivorous red kangaroo that’s 25 feet tall with huge sharp teeth,  but they were just too serious about it, and there was no punchline later on. Some people in the area even speculated enviously over who might be secretly hoarding stainless steel, in the same way we might speculate who had gold bars under the bed. Apparently one of the few source of stainless steel in the town was a small truck that would travel all across the outback towns selling scrap stainless steel arriving at each town for a day about once or twice a year.

Remember that this happened in a prosperous mining town with a buoyant economy, long before peak oil was to occur. Why the paranoia and scarcity about stainless steel? Stainless steel was imported to the manufacturing bases in capital cities which were over 1000Km away, and most of the mines didn’t use stainless steel for their equipment so very little of it ever went near a mining town.  So short of hacking up or melting down cutlery and cookware (which had an equally large transport cost) there was no real source of this material. While this parable is a bit of an aside it does demonstrate that scarcity of a material or resource really does determine its value and the way people begin to act around scarce resources.

The irony of the story was, if he had asked for solid silver to do the work, people would have been quite accommodating, they had it in several different nugget and bullion forms.

Scarcity is  often; right here – right now, rather than; somewhere – eventually.

I think you’ll look at cutlery differently from now on.

Scram bag: Char cloth tin

Char cloth is one of the easier was to turn a spark into an ember, which of course can be turned into a flame.

To make the char cloth you will need a char cloth tin.

A great source of char cloth tins are empty nugget tins, though other well sealing tins can be used.

Kiwi boot polish tin.

Make char cloth tin:

1) Remove all paint from the tin with sand paper. (otherwise it will stink as it is heated)

2) Make a small vent hole 2-3 mm diameter (perhaps with a nail) in the top of the tin.

Use of char cloth tin:

1) Add small pieces of cut up natural cloth (20 mm square) into the tin and close it. (wood or paper can also be used)

2) Place tin on the embers of a fire with the vent  hole facing up.

3) Wait for smoke to come from the tin, and wait for the smoke to stop.

4) Turn the tin over so the vent hole faces down. ( this allows both sides of the cloth to char properly)

5)Wait for smoke to come from the tin, and wait for the smoke to stop.

6) Remove tin from the embers and allow to cool.

7) Open to inspect the char cloth.

Char cloth quality tests:

If  it is brown it need to be cooked longer.

If it is crumbly too the touch  it was cooked too long and must be discarded.

It should be black and soft but not too fragile.

Store the char cloth in an air tight container. A small piece of tape or bees wax over the vent hole may be enough.

Char cloth use:

Place char cloth in your fire starting kindling nest and place char cloth in the center.

Using what ever method you have of creating a spark, attempt to create sparks on the char cloth.

The cloth will smolder with red orange ember lines flowing through the material. blow on it gently in the kindling nest and flames should take hold.

Fun facts about kiwi boot polish:

Invented in Melbourne, Australia by Scottish immigrants, Made in Indonesia, and now owned in USA.

The US army just calls it Kiwi, just like they call the fruit a Kiwi.

Connection to new Zealand? One of the inventors wives was from New Zealand.

Allegedly this boot polish cemented the Kiwi as a symbol of New Zealand.

Cost: free* ( Some assembly required.) or possibly free with nugget for your boots.