When troubleshooting a cold process soap recipe, there are several factors to look at. For instance, if your batch accelerated or riced, it may be the fragrance oil. If the batch is taking longer than usual to trace, it may be a high amount of soft oils, like olive oil, in the recipe. Another thing to investigate is your lye. If lye is past its prime, it can do some odd things in your soap.
Lye is an inorganic compound that is commonly found in drain cleaners. It is highly caustic and can burn the skin if not handled properly. Working with lye requires long sleeves and pants, close-toed shoes, a well-ventilated room, gloves and eye protection. Before handling lye, make sure to watch this Soap Queen TV video on lye safety. The Lye Safety Guide has more information on how to work withit.You need to be fully prepared and follow every safety precaution before getting started.
Working with lye requires safety gear like goggles, glovesandlong-sleeved shirts and pants.
Lye is necessary for the soapmaking process. By definition, soap is a chemical reaction between oil and lye. This reaction is called saponification. During the saponification process, the lye gets used up. That meansit is not present in the bars after they’re cured. Read more about saponification in the Where’s the Lye post.
For soapmaking, lye comes in two types. Sodium hydroxide lye is used to make solid cold process soap. Potassium hydroxide lye is used to make liquid soap. Read more about potassium hydroxide here. Both types of lye are dissolved in a liquid, like distilled water or milk. Make sure to always add the lye to the liquid, not the other way around. If the liquid is added to the lye it can cause a volcano-like reaction.You can use our Lye Calculator to find out how muchlye and liquid to addto your recipe.
Sodium hydroxide lye is used to make solid soap, and potassium hydroxide lyeis used to make liquid soap.
To ensure the lye works properly, we recommend using it within one year of purchasing. It needs to be sealed tightly and stored in a dry place. Lye is hygroscopic, meaning it attracts moisture. If it’s exposed to moisture in the air it won’t be as effective in your recipe, and the soap maynot saponify fully. The lye also needs to be kept in a cool place. It may lose its potency if stored in warmer temperatures. In the Soap Queen Lab, the lye is double sealed and stored in a box that is placed on a shelf. At home you can store it in a cupboard, in your garage, etc. Just make sure it’s clearly marked and out of reach of children.
Make sure to store your lye in a cool, dry place to extend the shelf life.
How can you tell if the lye is expired? The first clue is how it looks. Check out the photo below. The expired lye on the leftis more of a gray, off-white color than the lye on the right. It is also clumping in several spots because it has absorbed moisture from the air.
Above, the expired lye is shown on the left and the fresh lye is shown on the right. Notice the color difference!
Another clue the lye is expired is how it acts when added to water. Whenlye is added to distilled water, it gets really hot – up to 200° F. Expired lye won’t get nearly as hot. Below, we added 2 ounces of freshpotassium hydroxide lyeto 5.3 ounces of distilled water. The fresh lye was about 141° F when it was added to the water and stirred to dissolve. The expired potassium hydroxide lye only reached about 124° F. It also had a slightly cloudy appearance, even after thorough stirring.
If your lye solution does not get very hot, it may be expired. Above, the potassium hydroxide lye solution using expired lye only reached 124° F.
If you notice anything odd happening with your lye, don’t use it in cold process soap. Expired lye doesn’t saponify properly, meaning your soap may notreach trace. Read more about trace in this post. This can also happen if you accidentally usepotassium hydroxide lyein a solid cold process recipe. Make sure to check the label before adding it to your batch. If the soap does trace, it may not set up properly and can be soft or sticky to the touch.
Using expired lye can mean your soap won’t reach trace.
To avoid any wasted soap, make sure to keep your lye tightly sealed in a cool, dry place. We like to mark all of our bottles in the Soap Lab with the date it is opened. That way we can replace the lye after a year to prevent it from going bad. If you used expired lye in your soap and the soap set up, great! The soap is fine to use, albeit a little extra superfatted. If you used expired lye in your soap and your soap did not set up, there is no way to save the soap because we don’t know exactly how much lye it is short. To dispose of the lye,you can mix it with distilled water and pour it down the drain. Lye is actually found in most drain cleaners.If you’re worried about your drain, you can also contact your local waste management services to find out how to dispose of hazardous materials.
How do you store your lye to ensure it stays fresh? Have you ever used expired lye in your soap before?
FAQs
If you used expired lye in your soap and the soap set up, great! The soap is fine to use, albeit a little extra superfatted. If you used expired lye in your soap and your soap did not set up, there is no way to save the soap because we don't know exactly how much lye it is short.
Can you use expired lye for soap making? ›
If you're already using an immersion blender and still have trouble getting your soap to reach trace, check your ingredients. Old, expired lye can cause consistency issues; and living in a humid environment can cause it to weaken even faster.
How long does lye stay in cold process soap? ›
After 24 hours, using gloves remove the soap from the moulds and cut into bars. Leave the bars somewhere to cure for about 4 weeks. You can test if they are done by sticking your tongue on them (yes this is really what you do) to see if the lye is still active.
What happens if you use too much lye in soap making? ›
If you use too much lye, some lye remains in your bar, and it can be irritating to the skin.
How long is lye solution good for? ›
Store lye appropriately
The solution looks just like water, so you want to make sure everyone else in your home knows it's not safe to handle. The same goes for the lye bottle - make sure it's in a safe space and clearly labeled. It has a shelf life of about a year, and it does best in a cool and dry space.
Does lye lose potency? ›
If it's exposed to moisture in the air it won't be as effective in your recipe, and the soap may not saponify fully. The lye also needs to be kept in a cool place. It may lose its potency if stored in warmer temperatures.
What happens when sodium hydroxide expires? ›
Poorly stored or old caustic soda can start to decompose, resulting in a decrease in purity. It is best to check the expiration or manufacturing date on the product label to ensure the caustic soda is still within its recommended shelf life.
What is a good lye concentration in cold process soap? ›
Most beginner cold process recipes will use a lye concentration of 33%. There's one good reason why you should use this water content for your first batch of soap: it gives you more time to work.
Can you make cold process soap without lye? ›
NO, chemically-speaking, soap itself cannot be made without lye. Soap is made by blending oils (like olive oil or coconut oil), a liquid (water, goat's milk, etc.), and an alkali (lye). Lye is needed to convert oils into soap.
Why isn't lye used in soap anymore? ›
You can't make real soap without lye. All natural soaps have lye as an ingredient in them; synthetic chemicals can now be used instead of lye (like phthalate-free glycerin), but we wouldn't consider that natural soap because it contains no botanical ingredients or essential oils from plants or flowers.
The more soft oils (such as olive, sweet almond, rice bran, canola, etc.) the soap contains, the softer the bars will be. It may take more time to harden in the mold. The more hard oils the recipe contains (such as palm, coconut, cocoa butter, beeswax, etc.), the quicker the soap will harden.
How to fix lye heavy cold process soap? ›
To correct a lye-heavy batch, shred the soap as finely as possible, using gloves to protect your hands, and add to a slow cooker set on low. Add 1 tablespoon of distilled water and cover. Allow the soap to cook, stirring occasionally, until it has melted into a hom*ogenous solution.
What to do with old lye? ›
Ways of disposing of lye
If you have more caustic soda than you need, give it to someone who will make good use of it. Bring it to a DIY soap manufacturer, a plumber, an engineer, or a shopkeeper to resell it.
How long is lye active in soap? ›
You see, lye is an alkali. When an alkali is mixed with a fat (your soap making oils) it goes through a chemical reaction which produces a new molecule that is a salt. Once the soap has gone through the saponification process, which generally is complete in 24-48 hours, there is no longer any active lye left in it.
What temperature should lye and oil be cold process soap? ›
Keep your oils and lye around 40°C / 100°F (just above body temperature) to avoid false trace in most recipes. Unless you are using beeswax or other high melting point ingredients, keep temperatures below 50°C /122°F to avoid acceleration of trace and soap volcanos.
What is a substitute for lye in soap making? ›
In this method, you're replacing lye with baking soda, both of which are alkalies. However, lye is much stronger than baking soda. Heating up baking soda in the oven turns it from sodium bicarbonate into sodium carbonate, making it a slightly stronger alkali that'll better replace the lye.
What is the difference between food grade lye and regular lye? ›
In addition, bakers use food-grade lye, which is a higher grade lye with fewer impurities than technical grade sodium hydroxide. The standards for food-grade lye must meet guidelines set by the FDA, ensuring it's safe to use as directed with food.
What will happen if you use expired soap? ›
Using a soap past its expiry date isn't likely to be a huge safety risk, but it may not work as effectively. You might find it doesn't clean as well or produce that satisfying lather. Using rancid soap can also impact the fragrance and likely make for a less pleasant bathing experience.
Is soap made with lye bad for your skin? ›
Lye is a caustic substance that can certainly damage your skin if you're exposed to it. It can cause a number of problems, such as burns, blindness, and even death when consumed. But, and this is a big but, soap that is created with lye (which is all real soap) will do absolutely no harm to your skin.
Working with lye requires safety gear like goggles, glovesandlong-sleeved shirts and pants.
Sodium hydroxide lye is used to make solid soap, and potassium hydroxide lyeis used to make liquid soap.
Make sure to store your lye in a cool, dry place to extend the shelf life.
Above, the expired lye is shown on the left and the fresh lye is shown on the right. Notice the color difference!
If your lye solution does not get very hot, it may be expired. Above, the potassium hydroxide lye solution using expired lye only reached 124° F.
Using expired lye can mean your soap won’t reach trace.