Lye (also known as caustic soda) is a corrosive alkaline substance,
commonly, sodium hydroxide (NaOH). Previously, lye was among the
many different alkalis leached from hardwood ashes. Now, lye is
commercially manufactured using a membrane cell method.

Solid dry lye is commonly available as flakes, pellets, microbeads,
and coarse powder. It is also available as solution, often dissolved
in water. Lye is valued for its use in food preparation, soap making,
biodiesel production, and household uses, such as oven cleaner and
drain opener.


Sodium hydroxide, caustic soda

Potassium hydroxide, caustic potash

Sodium carbonate, soda ash




The list is fairly short and mostly common sense. There's no way
to make it interesting, but read through it anyway. Becoming
familiar with these lye and lye/water safety precautions will make
your soap projects rewarding, not painful.

1. Lye is a caustic and poisonous so treat it with care.

2. Be careful not to inhale the dust when working and work in a
well-ventilated area. Soapmaking is easiest if you have quick
access to the stove and sink, making the kitchen the ideal work
area. Use the exhaust hood when mixing lye or mix lye outside.

3. Have adequate space to work on. Protect all work surfaces.
Lye can "redesign" your kitchen!

4. Wear protective goggles and rubber gloves, long sleeve shirts
and close fitting clothing; protect your feet, no sandals.

5. Lye corrodes metal so remove all jewelry before making soap.

6. If you accidentally get lye on your skin, flush the area with
ordinary vinegar and wash well with soap and water. (Lye will feel
slippery on skin.) Lye in the eye necessitates a visit to the
emergency room.

7. Do not leave the area unattended. If you're tired or short of
time, leave soapmaking for another day.

8. When mixing lye with water, always add lye to the water, not
the other way around. Pour it carefully in a steady stream.

9. Do not place bowls/pots near the edge of the counter.

10. Never reuse lye containers, stirring spoons or molds for other

11. Do not attempt to heat lye in microwave or on the stove.

12. Children and pets should be kept away from the work area until
all equipment has been cleaned and put away.

13. Let soap cure undisturbed - away from children and pets.

Lye Safety Precautions




Sodium Hydroxide is a extremely important compound in our lives because it
has so many uses. It is a very common base used in the chemical industry
and is used for many things, many of which occur in our daily lives. One
of the most well known uses of Sodium Hydroxide is its use in unclogging
drains. It comes in many different brands of drain cleaners, but one of
the most common is Drano. It also comes in the form of lye soap which can
be used to wash practically anything, from the dishes to your face.

Sodium Hydroxide is also used quite a bit in food processing. The compound
is often used in steps for peeling fruits and vegetables, processing cocoa
and chocolate, thickening of ice cream, poultry scalding and soda processing.
Olives are soaked in Sodium Hydroxide along with other substances to make
them black, and soft pretzels are also coated with the compound to give them
a chewy texture.

Other uses include:

Used in processes to make products including plastics, soaps rayon and textiles
Revitalizing acids in petroleum refining

Removal paint

Etching aluminum

Dehorning of cattle

During two steps of the paper making process

Used in relaxers to help straighten hair however this is becoming less popular
because of the possibility of chemical burns

Sodium Hydroxide can sometimes be replaced with Potassium Hydroxide which is
another strong base and can create some of the same results.

Sodium Hydroxide Uses




Lye is an alkaline solution thatís often used for washing, making soaps,
and curing certain foods. Lye is sometimes called caustic soda because it
has a pH of about 13, which means itís extremely alkaline and can burn and
corrode skin, organic tissue, certain plastics, and other materials. You
can make your own potassium hydroxide lye by soaking wood ash in rain water,
and this type of lye is ideal for making liquid soaps. Working with lye is
dangerous, and requires a number of safety precautions.

Thing You'll Need

Hardwood ash

Metal container

Rain barrel

Wooden barrel



Stones and pebbles


Lye-safe buckets

Long rubber gloves

Safety goggles

Hard shoes

Part 1

Organizing Your Supplies

1. Collect wood ashes.

To make potassium hydroxide lye, you need the white ashes from hardwood fires.
When hardwood trees are growing, they draw potassium from the ground. This
potassium doesnít burn in the fire, and is still present in the ashes after the
fire. You can then leach the potassium from the ashes with water. After every
hardwood fire you have, allow the ashes to cool for a few days. Then collect the
white ashes and store them in metal containers.

The best hardwoods for lye water include ash, hickory, beech, sugar maple,
and buckeye.

To make lye using this method, you'll need enough ash to nearly fill a wooden

Donít use ashes from softwood trees, as these donít contain enough potassium.

2. Collect rainwater.

The second thing you need to make liquid potassium hydroxide lye is soft water.
Rainwater is ideal because itís soft and available in large quantities.

Set up a rain barrel in your backyard or under the eaves of your house to
collect rainwater. Make sure there's a filter on the barrel to strain out
leaves and organic debris.

Soft water has lower concentrations of other elements, so itís ideal for soap
making. Hard water will produce soap that doesnít lather.

You'll need at least 10 pints (4.7 L) of soft water to make lye water.

3. Drill holes in your wooden barrel.

After you fill your barrel with ashes, you'll run water through the ashes to
leach the potassium. The water needs somewhere to drain out of, so you need to
make holes. With a drill and a small drill bit, drill about six small holes
into the bottom of the barrel.

Concentrate the holes near the center of the barrel so the water will drain
into a bucket.

4. Add a layer of stones and straw.

Fill the bottom of the barrel with 1 to 2 inches (2.5 to 5 cm) of clean stones
and pebbles. The pebbles should be large enough that they donít fall through
the holes in the bottom. Cover the stones with at least 3 inches (7.6 cm) of
dried straw.

The straw and stones will act as a filter. The lye water will drain down through
the straw and stones, leaving the ashes and particles on top.

Part 2

Making Lye Water

1. Fill the barrel with wood ash.

Transfer the wood ash youíve collected in your metal buckets to the barrel.
Shovel the wood ash over top of the straw. Fill the barrel to within 4 inches
(10 cm) of the top of the barrel.

2. Prop the barrel up on sturdy blocks.

Mount the barrel on sturdy blocks so the holes underneath are accessible. The
barrel has to be high enough off the ground to accommodate a bucket underneath.

You can also mount the barrel inside an open wooden frame.

Make sure the barrel is sturdy and will not fall over.

3. Position the bucket.

Place a lye-safe bucket under the holes in the barrel. This bucket will
catch the lye water, so it has to be a lye-safe material. Acceptable
bucket materials include:


Stainless steel

Number 5 plastics

Heavy-duty plastic

4. Pour rainwater over the ash.

Slowly add rainwater to the barrel by the bucketful. You want to add enough
water in total to make the ashes wet, but not soaking. If you start to see
the water line at the top of the bucket and the ashes are starting to float,
stop adding water.

Pay attention to how many bucketfuls of water you add. This will give you an
idea of how many buckets of lye water to expect from the barrel.

You donít have to put a lid on the barrel, but make sure that itís protected
from rain in case you get a storm.

5. Put on your personal safety equipment.

Lye is very caustic and corrosive. It burns skin, causes blindness, and can
damage organic tissue and inorganic materials. When working with lye and lye
water, itís very important to be extremely careful and to wear personal safety
equipment, including:


Hard shoes or boots

Elbow-length plastic gloves

6. Collect the water that drains out.

After a few hours, the first run of lye water will start to trickle out from the
holes in the bottom of the barrel. Let the bucket underneath fill up to within 4
inches (10 cm) of the top of the bucket. When the bucket is full, carefully remove
it from under the barrel. Be careful not to spill the lye water.

Replace the bucket with a fresh one to catch the rest of the water.

7. Test the strength.

Your lye water has to be a certain strength before you can use it to make soap. The
lye water will probably not be ready after a single run, but you can test it. There
are four different tests you can use to test the strength of the lye:

Use pH test strips. You're looking for a pH of 13.

Use a pH meter to see if the pH is at 13.

Place a small potato in the lye water. If it sinks, the lye isn't strong enough.
If it floats, the lye is ready.

Dip a chicken feather into the lye. If the feather doesnít dissolve, the lye isn't
strong enough yet.

8. Run the water through again until itís strong enough.

Most lye water solutions will have to be run through the ash barrel at least a second
time. If your lye wasnít strong enough after the first run, carefully pour all the lye
water back into the ash barrel. Be extremely careful not to spill or splash the lye water,
as it can burn your skin.

Replace a bucket under the holes in the barrel.

Let the water drain through the ashes again.

The lye water that comes out the second time will be stronger.

When all the lye water has drained through a second time, test the pH again.

Run the lye water through again if necessary.

Part 3

Using Lye Water

1. Make liquid soap.

Homemade lye water made from potassium hydroxide is ideal for making liquid
soaps. You can also make your own castile soap, which uses a lot of fat to
make a moisturizing soap. ēPotassium hydroxide lye is not ideal for making
hard bar soaps. To make these types of soaps, use sodium hydroxide, which
you can buy from home improvement stores, farm supplies, and online.

2. Cure Olives.

There are several foods, such as olives and lutefisk, that are traditionally
cured with lye. You can use your homemade lye water to cure olives and other
foods at home.

3. Unclog drains.

Because lye is so caustic and eats organic materials like skin and hair, it
has long been used as a household cleaner and drain cleaner. You can use your
lye water to unclog drains in the laundry or utility room, clean bathtub drains,
and unclog sink drains.

How to Make Lye




Certified Lye

Food Chemicals Codex

Homemade Lye Soap

How to Make Lye for Natural Soap Making from Wood Ash

How to Make Lye from Scratch

How To Make Lye At Home

How to make lye soap


How to Pick Containers for Soapmaking (What is Safe to Soap In?)


Lye Safety

Lye Safety Guide

Lye Soap Recipe and Tips

Lye (Sodium Hydroxide) Basics

Making lye from wood ash

Making Wood Ash Lye from Ash to Crystals

Safely Working with Lye

Sodium Hydroxide

Sodium Hydroxide (Lye) Safety

Toxic Substances Portal - Sodium Hydroxide

What is Lye?


Working with Lye


Material Safety Data Sheet