Soap Making Lye Water

As one of the most important – and dangerous – steps in soap making, and because it’s common to all soapmaking processes, I’ve decided to make a single post just to let you know how to make soap making lye water, safely and without any concerns.

Make lye water by simply pouring lye into room temperature water. However, as lye is a corrosive and strong substance, and may cause chemical burning in your skin. Safety measures are required to make lye water safely.

Please, also check Learn To Make Cold Process Soap or How To Make Liquid Soap From Scratch to learn how and when to use lye water.

Table of Contents

Safety First!!

Soap making is a really fun and rewarding hobby. However, it may become a very bad experience if you don’t take the proper safety precautions. Because you are directly contacting with lye or potash, which causes chemical burning to your skin, this operation is the most dangerous in soap making.

On the other hand, if you follow these precautions, you will have nothing to fear. It’s like attending to fire in a fireplace: fire is very dangerous, but if you know what you’re doing, and you take precautions, it’s heartwarming to have it at home. Making lye at home will allow you to make handmade soap of very good quality.

Please, read Soap Making Safety Precautions first or watch the video:

Getting Started

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  • Do not start making the lye water without your safety equipment on: goggles, gloves and mask
  • Wear clothes that cover you completely
  • Make lye water in a very well ventilated area, near a window or ideally outdoors

How To Make Soap Making Lye Water?

To make lye water for soap, the simplest way is to pour lye into water and mix it well. There are some aspects to have in mind, however.

  1. Don’t use aluminium or metal of any sort except stainless steel. Lye dissolves metal and will contaminate your soap and damage your equipment.
  2. Always have your safety equipment on.
  3. Make lye water outdoors, or near an open window.
  4. Your water should be at room temperature. Might sound strange with distilled water, but if you are using an infusion instead of water, this is very important: allow the infusion to cool before making the lye water. Hot water with lye will make a frightening volcano effect
  5. Start by weighting the lye and the water separately with a digital scale. This is important as errors bigger than 1 gram might make your soap lye heavy, and therefore irritant
  6. Beware that the jug of water will heat a lot, up to 90ºC – 100ºC (194ºF – 212ºF). Keep it over a heat resistant surface.
  7. Always pour the lye into the jug with water. NEVER pour the water into the lye.
  8. Measure the temperature, if you are going to do cold process soap, to control the target temperature at which you should mix the lye water with oils and wait till it reaches the right temperature
  9. You should strain the lye water when using it for soapmaking, to prevent lye crystals from going into your soap batter. To be honest, I don’t follow this step very often and I never had problems, but I always make sure there are no “sandy” material (lye grains) at the bottom of the jug and all is dissolved.

Soap Making Lye Water Variants

Many soap makers use the lye water to color soap, as the color is more intense this way than if mixing the colorant after trace. Especially if the colorant is a natural one, like spices, herbs, vegetables or clays. You can also use: cinammon, turmeric, paprika, cocoa powder, green/pink/red/yellow clay, spirulina, calendula, etc.

soap making lye water

It is possible to use alternatives to distilled water: herbal infusions, milks, beer, juices, vegetable pureés, brime! Have in mind that using other liquids other than plain water is for experienced soap makers, as not all herbal infusions work and other drinks contain sugars that change the way the liquid and lye react – sugar accelerates the process, and also turns the water brown.

Also, this is the right time to add special soap addictives like sodium lactate, a salt solution that help with soap hardening (solidifying). This is especially important for castile soaps, or any soap with a lot of liquid oil.

A bottle with lye and a pitcher with water

Soap Making Lye Water

Learn how to make lye water for soap making! As one of the most important – and dangerous – steps in soap making, and because it’s common to all soapmaking processes, I’ve decided to make a single post just to let you know how to make lye water for soap, safely and without any concerns.
Prep Time: 10 minutes
Total Time: 10 minutes
Method: Soap Making
Cosmetic: Lye Water For Soap Making
Servings: 1 jug of lye water
Author: Sofia Matias




How To Make Lye Water

  • Make your lye water prefferably outdoors, or at least, near an open window.
  • Weight the lye/potash and water according to each recipe. Don't make errors above 1 gram.
  • Pour the lye/potash in the water. NEVER pour the water into the lye/potash, you may get a "volcano" effect or lye spilling.
    pour lye in water
  • Mix well with a silicone spatula or spoon. Don't breathe the vapours, they are very irritating.
    mix lye in water
  • When using potash, the reaction potash-water is even stronger than lye-water. Be ready for cracklings and a very slight volcano.
    Ingredients and jars to prepare lye water with potassium hydroxide
  • Be careful as the jug will get a really high temperature (near 90ºC – 100ºC or 194ºF – 212 ºF).
    lye water
  • For cold process, it is important to check temperature, in order to mix it with oils at a good temperature.


  • Basic lye water only uses lye/potash and distilled water. But you can make lye water replacing the water with any water-based liquid: herbal infusions, vegetable pureés, fruit juice, milk, coffee, even beer.
  • Some addictives to improve soap properties are also added to the lye water, especially ones that will react with lye or potash: sodium lactate, fine salt, citric acid, vinegar.
  • You can also add the ingredients we will be using as natural colorants: clays, spices, dried herbs in powder form.
    green lye water


Tried this recipe?Send a pic to @herbalcochete!

4 thoughts on “Soap Making Lye Water”

  1. Hi, you have triggered my curiosity to make soap myself. I have never thought about it, but after seeing your website, it has triggered my interest. 

    You have explained the process of making lye water very well. The videos make it easy to understand the process and how to do it. It should be easy to copy the procedure in the same way you have shown it.

    Safety is important as lye can cause severe injuries if not handled properly. By using safety glasses, gloves and a mask to cover your face, it should be a safe procedure.

    Is it latex gloves or rubber gloves you use? I expect rubber gloves. Further, I wonder about the specific requirements for the selection of the mask as well. What is the requirement for a mask?

    Thank you for a good article. I think I will try to make soap too. It seems like a lot of fun!


    • Hello Roy and thanks for your comment.

      I am so glad that, even a not so interesting post about soapmaking, sparks the interest about this hobby/craft in people 🙂 This is what this blog is all about: letting people know that they can make soap at home and how.

      About your questions: soda and lye water are dangerous but at the same level as pure bleach (not the perfumed one, but the one that smells strongly of chloride). So. like bleach, you shouldn’t smell its vapors and you shouldn’t let drops of the stuff to fall in your skin. 

      Any gloves and mask can do that job. If you feel safer with rubber gloves and a special mask for fumes, go ahead and purchase it. But, really, it’s not necessary.

      Two more things to have in mind that makes preparing lye water safe is: do it in the outdoors or next to an open window; cover yourself completely with clothes – do not feel tempted to wear only a t-shirt because it’s hot and “you will be careful”. Wear covered shoes as well.

      Have in mind that the lye water will be mixed with oils later on and the soap mixture at that point IS still corrosive. So, doing the whole soap fully clothed makes it really safe for you.

      When is it fully safe? 48 hours after the soap has set is a safe rule-of-thumb.

      Hope this clarified everything for you!

      Cheers and stay safe!


  2. Hello Sofia, I don’t even know that we should not start making the lye water without safety equipment on: goggles, gloves and mask. After reading your article and the video you share, it was very easy to understand and step by step tutorial. Is there any benefit of using lye water that we make by ourself instead of buying from outside? I have share your article with my friends who also looking for this too! Thank you so much!

    • Hello Evelyn and thanks for your comment.

      Be very careful when dealing with alkali products like lye water! It causes chemical burns. If your skin gets a good portion of it you will have a nasty burn – fortunatelly, because I’ve ALWAYS used my safety equipment, I don’t know what that is. The most I’ve had was some hitching I’ve promptly washed in abundant water.

      Be as cautious as myself, and always use gloves, mask, goggles and clothes covering you completely (shoes included) 

      About purchasing lye water, the issue is that you no longer have control over ingredients in it. 

      First, many products called “lye water” are water with an alkali – sodium carbonate, potassium carbonate, … . What you want for soap is either sodium hydroxide or potassion hydroxide. Other alkali will make other sort of chemical reactions, maybe not exactly resulting in soap. Some products containing lye water are meant for cleaning and may contain other chemicals (such as ammonia) you also don’t want in your soap.

      Second, you loose control on lye concentration (water:lye ratio). Lye concentration is important, as it influences trace (simply said trace is how fast the soap batter will set into a solid substance). Sometimes you wish to slow it down, sometimes you wish to accelerate it. It also influences the appearance of soda ash, a sort of white powder covering your soap, which is harmless but changes the visual of your soap (I actually like it).

      So, every soap maker makes their own lye. But thanks for the question is a very interesting one.



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