Found on the Internet: How to Weld

Despite my penchant for post-apocalyptic knowledge, I’m still a huge geek at heart.  I watch a lot of youtube videos and spend a lot of time on the internet.  I’ve watched Geek Beat TV since it was Geek Brief and recently they’ve been branching out to things not so tech related.  For instance, the above video shows (in much better detail than I could show you) how to weld.  I’ve written before on welding, and I feel like it’s a skill that could be helpful today as well as in an apocalyptic scenario.

How to Make Biodiesel

Traditional diesel fuel is made from petroleum, and in a post-apocalyptic world that will be hard to come by.  Thankfully, biodiesel is an alternative that can be made from any organic oil or fat that doesn’t require any kind of modification to your diesel engine.

Generally, you are adding a catalyst to a triglyceride-rich liquid in order to break a glycerin molecule off of the fatty acid chains in the oil and forcing each of three fatty acid chains to recombine with the introduced alcohol to essentially create a new alcohol.  This process is called transesterification.

Transesterification: ester + alcohol = different ester + different alcohol
Transesterification: ester + alcohol = different ester + different alcohol


Organic Oil/Fat

This can be nearly any kind of oil or fat (I’ve seen biodiesel made with rendered pig fat).  There are a few considerations to take into account though:

  • Peanut oil, coconut oil, palm oil, tallow, and lard all have a higher clouding point than other oils, meaning that they start to crystallize and gel at a higher temperature.  This means that they will work perfectly fine in warmer weather, but may cause problems in cooler temperatures.
  • Olive oil, peanut oil, palm oil, tallow, and lard have a higher acidity.  This can interfere with the transesterification process and means you probably want to titrate a sample (explained later) to determine if extra lye will be needed.
  • If you are using used oil, you need to process it before going forward with the recipe.

Rapeseed (or canola) oil, corn oil, soy oil, and sunflower oil are considered to be the preferable choice for biodiesel production.


It is possible to use either methyl alcohol or ethyl alcohol for biodiesel.  Methyl alcohol is preferable because there is less work involved with methyl alcohol.  Either way, you want as close to 100% pure as possible.


There are two types of lye potassium hydroxide (KOH) and sodium hydroxide (NaOH).  Either can be used, but KOH is preferable since it dissolves easier in alcohol.  Also, conveniently enough, it can be made per the instructions I give in How to Make Lye.


  • 10 parts oil
  • 2 parts methyl alcohol or 2.7 parts ethyl alcohol
  • 3.5 grams NaOH or 4.9 grams KOH per liter of oil used (plus any excess lye as indicated in titration for used oil)

The Process

Biodiesel and Glycerine separated into layers
Biodiesel and Glycerin separated into layers

Mix your alcohol and lye in an HDPE container (like a milk jug) and swirl occasionally until all the lye is fully dissolved.  This could take as little as 10 minutes for KOH and as much as overnight for NaOH.  This creates you methyl or ethyl esters.

Blend the ester mixture with oil/fat heated to 55C for roughly 30 minutes.

Let the mixture settle for 24 hours.  In this time, transesterification will occur, leaving behind glycerin as a by-product.  Three distinct layers will form, the heavy (bottom) layer is the glycerin, the light (top) layer is the biodiesel, and the middle layer is a soapy emulsion created by the reaction of lye with oil.  You can keep the glycerin, as it is useful in other situations, but unneeded for the rest of this recipe.  Move the biodiesel into a different container, ensuring that no glycerin or soap is carried along, and either store the glycerin or through it out.

Quality Testing

  • The Wash Test – Put a small amount of fuel in a PET bottle with water and shake vigorously for  approximately 10 seconds.  Let it sit for a half an hour.  If water separates from fuel with a very thin, foamy layer between (or no layer at all), then you’ve produced quality fuel.  If they don’t separate or there is a thick foamy layer, then your fuel is of poor quality.  This can be caused by too much lye or contaminants present acting as emulsifier.
  • The Methanol Test – Mix 25ml of biodiesel with 225ml of methanol.  If anything is going to separate, it will happen nearly instantly.  Each milliliter of biodiesel that separates from the methanol equals a 4% impurity.  Ideally, nothing will separate, meaning your fuel is 100% pure, but a little bit won’t hurt.


After testing to ensure your fuel is good you need to “wash” it.  This process removes any physical impurities or unconverted ingredients from the fuel, as these can all cause problems in your engine down the line (lye can corrode the fuel injectors and fuel tank, glycerin and soap can clog any number of parts, etc).  Mix 1 part fresh, clean water with 2 parts biodiesel until it appears homogenous.  Let the mixture settle for several hours, then drain water.  Move fuel to new receptacle and repeat process 2-3 times.  Let the fuel sit for several days. once it is no longer cloudy, it is “dry” and ready to use.  If it doesn’t clear up, you can try washing it again.

Processing Used Oil

You can use “certified pre-owned” oil to make biodiesel, you just need to do some things to it first.

Cleaning Old Oil

Some people recommend filtering the used oil first, but I say that it is unnecessary.  All the gunk and goo in the old oil will sink to the bottom and since you are usually working with the top layer of a separated liquid, you are naturally filtering it as you work with it.  However, there is a significant amount of water suspended in used oil (typically from the food cooked in it) and that can be a problem.

To remove the water, bring the oil to a boil at 100C and leave there until boiling slows, then boil at 130C for approximately 10 minutes.  This should ensure that most of the water is removed.


Every time you use or heat oil you create free fatty acids, which are basically broken-down triglycerides.  This means that there is more work required to convert your oil into biodiesel than with new oil.  This work is done by adding extra lye to the process.  To find out how much more lye to add, we use a process called titration.  This process should also be used if you are using ethyl alcohol instead of methyl alcohol, or an oil with a higher acidity.

First, make a 0.1% lye solution by mixing 1g of lye into 1 liter of distilled water.  Now dissolve 1ml of oil in 10ml of isopropyl alcohol.  At this point you need to choose a way to determine the pH of the oil/alcohol mixture.  You can use a pH tester, phenolphthalein droplets, or (if push comes to shove) red cabbage juice – seriously it indicates pH really well..  Add the lye solution drop by drop until pH is around 8-9.  If you’re using phenolphthalein, this is indicated by the liquid turning a pinkish color, if you are using red cabbage juice you are looking for a blue/blue-green color.  The number of milliliters of lye solution added to the oil solution equals the additional number of grams of lye per liter of oil to use in the transesterification process.


If you want to get super technical in your measurements, the amount of KOH used depends on the strength.

Purity Measurement (in grams)
99% 4.9
92% 5.3
90% 5.5
85% 5.8

Red Cabbage Juice

pH 2 4 6 8 10 12
Color Red Purple Violet Blue Blue-Green Greenish Yellow

How to Use a Compass

In the modern world, most people don’t have to think about how to get from point A to point B. The most difficult thing anybody has to do is look at a road atlas. While land navigation has become more of hobby than a skill, in the event of an apocalypse, those who do practice it would have an advantage over those who have mostly depended on GPS to get them where they’re going. Of the two basic skills that encompass land navigation, reading a compass is the more difficult but by far the more rewarding.

In the modern world, most people don’t have to think about how to get from point A to point B.  The most difficult thing anybody has to do is look at a road atlas.  While land navigation has become more of hobby than a skill, in the event of an apocalypse, those who do practice it would have an advantage over those who have mostly depended on GPS to get them where they’re going.  Of the two basic skills that encompass land navigation, reading a compass is the more difficult but by far the more rewarding.

Basic Usage

A typical compass face

In general, using a compass is fairly simple.  Most compasses have a floating needle that always points to the north magnetic pole, but there are some (usually cheap keychain compasses) that the face is the floating piece and the needle doesn’t move. Either way, all you have to do to get your “bearing” is to point the north end of the compass in the direction you are facing and read the little number on the outside ring of the compass that the needle points to.  This is called the bearing and gives you an accurate idea of which direction you are heading in.  Most compasses are numbered from 0 to 359 (for the 360 degrees of a circle) and each right angle (0, 90, 180, 270) is a cardinal direction.  Once you’ve taken your compass bearing you need to adjust for magnetic declination (discussed next) to get your map bearing and then you can navigate yourself very accurately anywhere in the world.

If you look at the face of a compass, you’ll notice that the face appears to be backwards.  This is because the needle always faces north.  So if you turn east the needle is still pointing north, but on the face of the compass the needle is pointing at east.  When using a compass, be aware of your surroundings – metal objects and electrical objects can have an effect on your reading.  Anything from power lines (which can affect your reading from within 55m) all the way down to jewelry (which practically have to be touching the compass to affect it) can have an adverse effect on your readings.

Magnetic Declination

Magnetic declination is the term used to describe the difference between “true north” and “magnetic north”.  Where true north lies at the top of the world, the north magnetic pole lies in the Arctic Ocean just above Canada.  The north you read on a compass is actually magnetic north and because of this, you have to account for the difference between the two if you want remotely accurate readings from your compass.  There is no easy formula for figuring this out because the north magnetic pole moves.  Most topographical maps will display the magnetic declination in the legend, but in the case you only have your compass, or your map is more than a few years old, you can take a reading at night of either Polaris (the north star) if you are in the northern hemisphere, or based on the Southern Cross constellation if you are in the southern hemisphere.  Taking a bearing from the Southern Cross takes a little more effort because you have to visualize a point in the sky.  Basically, you find the Southern Cross and draw a line down the long end of the cross, then find the bright pair of stars to the left of the Southern Cross and draw a line that runs perpendicularly to them.  Now the point you want to aim at to get your bearing is the point at which your two imaginary lines meet (see picture).

How to find due South in the southern hemisphere
Picture from

The Lensatic Compass

A lensatic compass
A lensatic compass

There are a number of different types of compasses, but the compass you will want in a survival situation is a lensatic compass.  The lensatic compass was designed for use by the military.  They’re durable and incredibly accurate.  One of the most important features of the lensatic compass is that it uses a copper induction dampening system.  Where most compasses suspend the needle apparatus in a liquid in order to keep it free floating, a lensatic compass does not, so it can be used without fear of the liquid freezing or changing pressure because of temperature or elevation.  If you plan on purchasing a lensatic compass, be careful in your purchase!  Lensatic compasses are expensive, so there are a lot of imitation compasses on the market that don’t work quite right.

Center-Hold Technique

Proper center-hold technique
Proper center-hold technique

The Center-Hold technique is the most common way to hold a compass and get an accurate measurement.  This technique can be used with any compass and can be performed while walking.  It is less accurate than some other techniques but perfectly acceptable if you are only trying to go in a general direction.

To perform this technique, rest the compass on both thumbs at waist level and parallel to the ground, held between your index fingers (as pictured above).  To take a reading, just look down at your compass.  The needle will be pointing in the direction you are facing.  The reason this is ideally suited to taking readings while moving is because while you are walking you can simply glance down to see what direction you are walking in, but this will only give you a general idea.

Compass-to-Cheek Technique

Proper compass-to-cheek technique
Proper compass-to-cheek technique

If you have a lensatic compass and you need a more accurate measurement, the Compass-to-Cheek technique is a much more suitable technique.  It is far more accurate than most other sighting techniques, but it takes longer to get your reading and must be done from a stationary position.

Open the rear sight and cover of the compass to form a front/rear sight configuration.  Hold the compass level and against your cheek.  Line the rear sight up with the sighting wire in the front cover and then line the sighting wire up with the landmark you are trying to get a bearing on.  Without moving, look down through the lens to get the bearing of the landmark.

Reverse Sun Dial Technique

If you find yourself without a compass, all is not lost.  Did you know you can use your wrist watch to tell directions?  Take your watch off and orient it such that the hour hand is pointed in the direction of the sun.  Visualize a line on your watch directly between the hour hand and the twelve o’clock line.  This is the north/south line, where north is in the direction furthest away from the hour hand.  What you are doing is essentially reversing the premise under which a sun dial works.  Instead of using the suns position and a general understanding of directions to determine the time, you are using a known time and the suns position to determine a general direction.  You don’t even need an analog watch for this to work!  You just need to be able to visualize the angle at which the hour hand would be at any given time and where the 12 o’clock line would be in relation.

Alternatively, if you have time to do this, you can put a stick in the ground, mark the tip of the shadow, wait 15 minutes and mark the tip of the shadow again.  If you connect point A to point B you have created the east-west line.  West is always in the direction of point B to point A (the direction the sun is moving).

Further Reading