Making soap from water, fat, and wood ash

Before I first made soap I read 11 instructional articles and watched two videos online. These are linked at the end of the post.

While the articles were helpful, my lye to fat ratios were significantly different.

I also found that my lye and fat made a hard bar soap whereas most people ended up with a liquid soap. If they wanted a bar soap they had to add salt or some other additive. Something in my soil/wood/ashes led to a harder bar soap as the end result.

Additionally, I found that if I cooked off all of the water, as was advised in some of the instructions, my soap tended to crack. I now leave a little water in my soap.

This is how I think of making soap after completing a few batches…

There are three components: water, lye, and rendered fat.

You can use one of the recipes (linked below) for starting ratios but ultimately you will need to develop your own ratios because each batch of lye is different. The type of fat may effect outcomes too. Therefore it is more important to know how to identify the signs that indicate when the ratios are out of balance so you can make adjustments.

One of the other things that I learned that wasn’t very clear from the online instructions is that you can always remelt down the soap and add components until you get it right. Keep track of your ratios and adjustments as this will give you a good idea of where to start for the next batch. If you use the same ingredients and the same batch of lye, you can develop an accurate recipe.

First I’ll cover how to make and acquire the components. Then I’ll go over how to combine them.


I collected wood ash from deciduous trees: willow, chicai (spelling?), and some poplar. Hardwood trees are generally recommended as they produce a stronger lye from their ashes. The willow and poplar are not very dense but are considered “hardwoods.” I avoided pine and similar evergreens (“softwoods”) because the resins are not supposed to be good for soap making.

After obtaining about 8-9 gallons (36 liters) of ash, I began the leaching process.

I put the ash through a home made sifter to remove the charcoal. Some internet sources claimed that the charcoal made no difference, others claimed that removing the charcoal produced a lighter color soap and improved the quality of the lye.

This picture shows my ash sifter. There are two metal buckets, one smaller that sits inside the bigger bucket.

The bigger bottom bucket collects the sifted ashes.

The smaller top bucket has many 1/4 inch holes drilled into it. (Note: I recommend a slightly smaller hole size, as charcoal chunks bigger than I’d prefer still get through the 1/4 inch holes.)

This is a picture of the coals retained in the top bucket after the ash was sifted. The ash from the wood stove is placed in the small bucket with holes. This small bucket is shaken over the big bucket until the ash has fallen through.

In this picture above I am using a pot as a measuring device. I poured ash from the metal can into the pot. On the left is a 5-gallon (20 liter) bucket lined with a pillow case. I make sure that the pillowcase reaches the bottom of the bucket as I want the ashes to sit in the bottom for this part.

I put 3 pot-fulls of ash into the 5-gallon (20 liter) pillowcase lined bucket.

I then put three consecutive pot-fulls of boiling water into the 5-gallon (20 liter) bucket. I use the same amount of water (by volume) as ash. Three pots of ash and three pots of water per 5-gallon (20 liter) bucket load. The pot size was close to 6 quarts (6 liters). Lye is a water soluble chemical present in the ash. What you essentially want to do is create an ash tea, then drain the water with the lye in it. The hot water is supposed to more effectively extract the lye than cold water. I used spring water.

Note: I did this in an outdoor bathroom. When ash is boiled, released vapors may be harmful.

I kept the plastic 5-gallon (20 liter) bucket covered to retain the heat from the hot water. In this photo I have a metal can sitting on top of the 5-gallon bucket to act as a lid. I then let the hot water and ash mix sit over night.

I pull out the pillowcase in the morning, letting much of the water drip through into the bucket.

Then I secure a second pillowcase over the bucket. I secure it so that the bottom sits about half way down the bucket. I want the pillowcase to be above the lye water. I don’t want the new pillow case to be submerged in the lye water in the bucket.

I then place the original pillowcase with the wet ashes inside (on top of) the new pillowcase. I let the lye water drain through both pillowcases into the bucket below for a couple of more days.


After a couple of days, I remove both pillow cases. The lye water will be a brown color in the bottom of the bucket.

Pour the lye water into a pot. I boil off 75% of the water to concentrate the lye.

As the water is boiled off the lye becomes more concentrated. Lye can reach a pH of somewhere between 11-14. It can be highly caustic. It can burn skin or even cause blindness if it gets in the eyes. Lye is used to break down grease and unclog pipes. Be sure to wear safety glasses and gloves when handling concentrated lye.

Build an outdoor fire to cook off 75% of the water in the lye solution.

Do not put your pot of ashes in water to cook on a stove indoors. Some of the online instructions show people doing this. This is dangerous for your health as the vapors can make you sick. I tried it, thinking my un-insulated drafty house had enough airflow to avoid problems with off gassing. Unfortunately, I experienced esophageal stricture from being exposed to the vapors.

In this photo I am using a stick to measure the water level. When I first started boiling the water I dipped the stick into the liquid. Then I made a notch on the stick 1/4 of the way up from the bottom of the wet part of the stick. I used this notch to gauge when to stop boiling off the water.

I now have my lye with some water in it. Next I need to prepare the fat.


I used goat fat in this case. I collected the fat surrounding the stomach and organs of the goat.

I have explained how to render fat in two prior posts BURNING GOAT FAT FOR LIGHT IN PATAGONIA and PROVISIONING THE JOURNEY, so I won’t go over it again here.

Here is my fat disc.

I chop it up into smaller parts.

I put the chunks into a pot and melt them.

Once the fat is liquefied, I take the fat outside to mix with the concentrated lye.


The pot in the bottom left contains the fat. The pot in the bottom right has the lye water and a ladle. These will be combined in the pan above.

I used the ladle to measure my ratios. I add the lye water to the pan first. Be careful not to add lye water to very hot fat or it could splatter and sizzle, getting lye/hot oil on you.

For me my ratio was about 4 parts lye water to 1 part fat. This differed markedly from most of the recipes that I read.

I add the oil just after I put in the lye to the pan.

Stir this a bit as you bring it to a boil. I typically boil it for an hour or two.

Stir occasionally as it simmers.

This is a photo of a different batch, hence the clay pot. Toward the end of the process you will want to remove the pot from the heat. As it cools continually stir to keep things well mixed. This is pretty much how you want it to look. Notice the streaking that follows the spoon. This indicates that it has reached the correct consistency. It will be thick like pudding.


I cut up old plastic containers to make molds.

Here is four molds from the plastic jar.

You don’t want the soap to be too hot or too cool. If too hot it will spill through the bottom of the mold. If too cool it will come out lumpy with air pockets.

The front row in the photo had a batch that came out nice. The middle and back row batch had a bit more lye than necessary: notice the brown liquid puddles sweating out. This is not necessarily a problem. You will just have some “frosted” white powder crystallizing of the lye on the outside of the soap when it dries. Once you use the bar of soap a few times the extra lye is washed off. I would rather have a little too much lye than a little too much fat. I have read that excess fat can make for greasy soap, though I have never had this problem. For the next batch I might add a little more fat to “soak” up the extra lye.

Finished soap! My soap cleans very well and even suds up pretty good. I don’t add egg or sugar to create a suds-ing effect.


This photo shows lye (the brown liquid near the stirring spoon) that has not yet reacted with and integrated with the fat. I would continue stirring to see if the liquid integrates. If not I would add more fat.

This is a photo from a batch that was boiled too long (too much water lost) and has too much lye. I think that the lye is what looks like brown sugar in the pot. My solution is to add some more fat and a little water, then reboil and see where things stand.

This photo has fat separated to the right and the “brown sugar” looking lye present. The way that I interpret these results is that the fat did not mix well. Looking at the lye to fat ratios, I would add a little more water, more fat and reboil it to see how it turns out.


Wood ash (hardwoods)
Stirring stick or spoon, not plastic
Stainless steel pot with lid
5 gallon bucket
Pillowcase (x2)
Two metal buckets
Drill with 1/4” bit (I would use a slightly smaller hole size in the future)
Plastic bottle molds
Gloves and safety glasses


Lye – Wikipedia
Make Your Own Ash Lye Soap – Live The Old Way
Making Lye From Wood Ashes – Live The Old Way
Turning your Wood Ash Into Lye Fir Soap Making – Raven’s Roots
How To Make Homemade Soap From Ashes – Farming My Backyard
How To Make Lye For Natural Soap Making From Wood Ash
How to Make Soap from Fat and Ashes – Homestead Survival Site
Soapy Stuff Wood Ash Lye
Lye From Wood Ash – Journey to Forever
How To Make Hot-process Soft Soap – DIY – Mother Earth News
How to Make Lye 15 steps (with pictures)


Making Lye Soap From Wood Ash and Lard

There is a lot more soap making content online now than when I looked previously. A search will yield more videos and articles.

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