How to Handle Potassium Hydroxide

When making soap from scratch, there’s one thing you just can’t avoid: lye. Without lye, your soap just isn’t soap! Working with lye may seem daunting at first, but if you learn proper handling techniques, take precautions and follow basic safety guidelines, there is no reason to fear it. You may be familiar with Sodium Hydroxide, which is used to make solid cold process soap, but today we’ll cover Potassium Hydroxide, which is used exclusively in liquid soap.  Although the rules for working with Potassium Hydroxide are similar to working with Sodium Hydroxide, it is important to understand and recognize the differences. Plus, it’s always nice to have a general lye safety refresher! To learn more on general lye safety, check out this blog post.

Potassium Hydroxide is a type of lye specifically used to make liquid soap. It is also known as potash, lye or even KOH. This is the chemical that induces saponification of the fats and oils to create liquid soap. Even though making liquid soap is different than making bar soap, it’s still vitally important that you use the correct amount of lye in your recipe. Our lye calculator makes this easy and allows you to select liquid soap as an option.

Potassium Hydroxide is hygroscopic (meaning it attracts moisture), so be sure to keep it in a sealed container in a cool dry place. If you leave it in an open container for even a day, it can attract enough moisture to throw off its weight enough to ruin a recipe.  If you leave it out for an extended period of time, it can attract enough moisture from the air in the room to turn completely liquid. When handling Potassium Hydroxide, give it the same safety considerations as you would with Sodium Hydroxide. It is a hazardous material, and being educated about safe handling practices is key when handling Potassium Hydroxide. As with any other type of lye, Potassium Hydroxide will emit some fumes, so be sure to soap in a well-ventilated area.

Always add your lye to your water, and never the other way around. Adding water to lye can cause a volcano-like reaction. Unlike Sodium Hydroxide, Potassium Hydroxide reacting with water makes a faint crackling or groaning sound — a somewhat subtle version of adding milk to Rice Krispies cereal.

When working with lye water, wear goggles that protect your eyes from all sides because alkali burns can cause blindness. If you wear glasses, check your local hardware store for goggles that are big enough to fit over them. Always wear an apron and gloves. Rubber dish gloves are great, but if they’re too bulky you can use thinner latex gloves.  Pair your gloves with long sleeves because the less exposed skin you have, the better. Finally, use a heat safe container to hold your lye water, and use silicone or stainless steel tools to stir (no wood). Never use any tools or bowls containing aluminum as that will create highly flammable hydrogen gases. Remember that when Potassium Hydroxide is mixed with water, it produces a reaction that heats the water up substantially, making it all the more important to mix lye in a heat safe container.

Never leave your lye water (or lye) unattended or in an place where children or pets may come in contact with it. It only takes a few seconds for an accident to happen! If you do need to leave the lye unattended for whatever reason, cover the container with a piece of plastic wrap and use a sticky note to clearly label it as a hazard.

If there is an accident:

If swallowed: Rinse mouth with water and drink one or two class of water. Do not induce vomiting! Immediately get medical attention or call your poison control center at 1-800-222-1222.

If in eyes: Immediately flush eyes with water. Remove any contact lenses and continue to flush eyes with water for at least 20 minutes. Immediately get medical attention or call your poison control center at 1-800-222-1222.

Lye water on skin: Wipe solution from skin and remove any contaminated clothing. Flush skin with plenty of water for at least 15 minutes and then wash thoroughly with soap and water. Contact a physician or call your poison control center at 1-800-222-1222.

Raw soap on skin: Even after it has been mixed with oils, lye can still be dangerous. If exposed skin comes in contact with raw soap batter, flush with water for 5 minutes and then wash thoroughly with soap and water.

Just like any tool, Potassium Hydroxide can be used safely and carefully to create wonderful liquid soaps for personal or business use. Use it responsibly.

What are you experiences working with Potassium Hydroxide? Let us know your best tips and tricks to work with it in the comments below!

 

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43 Comments

  1. Stephanie says

    The emergency info on lye is dangerously wrong. If it does come into contact with your skin washing it with only water will make the burn 100 times worse. Vinegar should be used immediately to neutralize the lye then be rinsed with water. Please make sure you research safety before posting false steps that could cause serious harm. Ty

    • Kelsey says

      Hi Stephanie!

      Our Material Safety Data Sheet suggests flushing the area with water. We definitely recommend using water and not vinegar. If you’d like more information, I’d be happy to email you a copy of our MSDS sheet. :)

      Many soapers keep vinegar on hand, believing it neutralizes lye burns. There is some controversy in the soapmaking community about washing lye burns with vinegar rather than water. Adding vinegar (an acid) to lye (a base) creates a chemical reaction that releases more heat. Additionally, the act of putting vinegar on a lye burn hurts. We recommend using water instead.

      Although vinegar should not be used to treat lye burns on skin, it can be used as precaution during the cleanup process. A quick wipe of your workspace with a vinegar-soaked rag will neutralize any lye dust that may have gotten on the surface.

      Read more in the Back to Basics: Lye Safety Guide: http://www.soapqueen.com/bath-and-body-tutorials/tips-and-tricks/back-to-basics-lye-safety-guide/

      -Kelsey with Bramble Berry

    • J says

      Stephanie. . . . “Please make sure you research safety before posting false steps that could cause serious harm”. Perhaps you should take your own advice and do more research before you make suggestions. I’ve seen umpteen videos and written blogs where vinegar is recommended but I’ve also read the MSDS sheet for lye and visited the CCOHS (Canadian Centre for Occupational Health and Safety) and vinegar is never mentioned.

      Most people who recommend vinegar are amateur soap makers going off incorrect information. This is one of the biggest dangers of the internet. One trusted or seemingly knowledgable person says ‘do this’, hundreds of people pass it on and before long everyone is saying the same thing.

      Vinegar is for CLEAN UP. Only. Pass that along.

      • Kelsey says

        Hi J!

        We definitely recommend using water, as it is what’s suggested in our MSDS.

        To prevent lye spills on the skin, it helps to have all your safety gear on – including goggles, long sleeves and pants, gloves and close-toed shoes. :)

        -Kelsey with Bramble Berry

  2. Gahigi says

    I copied and pasted this from the comments section on an older post from another site because I don’t think I’ll get any replies as it was written in 2009 or so. Anyway thanks for any help.

    I know this is an old post so I can only hope I’ll get an answer. I’m not trying to make soap but I had some KOH that was in the same plastic container I bought it in. I bought it about 7 years ago and never did anything with it but this morning it blew up, got on my carpet, and put a dent in my dresser like a huge bruise that cracked. I tried to clean it up with water and a towel being careful not to burn myself but I didn’t get it all up. It won’t stick to a wet towel very well so I thought maybe some vinegar would help since I believe KOH is negative and vinegar is positive but I don’t know how it would react with it. I was fortunate that most of it remained in the container but there’s still a little on my carpet and some in my dresser. I don’t even know what to do about the clothes. I just need some ideas on how to clean it up. Thank for any help

    • Kelsey says

      Hi Gahigi!

      Here is what our Material Safety Data Sheet says to do with potassium hydroxide spills:

      “Use appropriate tools to put the spilled solid in a convenient waste disposal container. If necessary, neutralize residue with a dilute solution of acetic acid. For large spills, chemical acts as corrosive. Neutralize the residue with a dilute solution of acetic acid. Stop leak, do not get water inside container. Do not touch spilled material. Use water spray to reduce vapors. Prevent entry into sewers, basements or confined areas. Call for assistance on disposal.”

      I would recommend sweeping up all the dry particles of lye, making sure you’re wearing gloves, goggles, long sleeves and pants the whole time. My worry is that even with the acetic acid, those lye remnants will remain in the carpet, which can be dangerous. I would recommend calling a local cleaning agency for help. They may be able to offer tips, and thoroughly clean the areas where it spilled. In the meantime, steer clear of that area. If any gets on your skin by accident it may burn you.

      -Kelsey with Bramble Berry

  3. Rosy says

    I have a question ! I’ve been trying to purchase my lye where I live, instead of ordering it through amazon because of the shipping charges and the extra time that it takes. But the stores that carry the lye around here sound a little “untrue” when I ask them how pure the lye that I’m getting is. Some sound even confused when I ask what percentage of Sodium Hydroxide does their lye contain. So my question is this. How pure should the lye be so it works fine for the soapmaking process, and if there some way that I can test the pureness myself, when I feel unsure of the product that I’m buying.

    THANKS SO MUCH !! any comments will be much appreciated !!

  4. Michelle says

    I cannot find information anywhere on Brambleberry concerning the purity of your KOH that you sell. I am assuming it is 100% because the most common other purity value is 90% — and in the latter instance it usually says so on the container.

  5. Kaitlyn says

    The protocol for first aid is wrong. Acid into water, never the reverse-this is as important for first aid as the soap! Using distilled white vinegar is a far more effective neutralizer than water. As always, do your own research before using any chemical. Consulting your local Poison Control as well as requesting the MSDS from the manufacturer for your chemicals is the safest bet. Happy (and safe!) soap making!

    • Kelsey says

      Hi Kaitlyn!

      According to our MSDS from the manufacturer, if the lye comes in contact with your skin, remove the affected area of clothing. Then, flush the skin with plenty of water for at least 15 minutes. Next, cover the irritated skin with an emollient. I’d be more than happy to send you a copy of the MSDS if you like. :)

      Many soapers keep vinegar on hand, believing it neutralizes lye burns. There is some controversy in the soapmaking community about this. Adding an acid (vinegar) to a base (lye) creates a chemical reaction that releases heat which burns. Additionally, just the act of putting vinegar on a lye burn hurts. For this reason, both the Material Safety Data Sheet and the Agency for Toxic Substances & Disease Registry recommend rinsing lye burns with water for 15 minutes. Specifically the ATSD recommends

      1. Immediately brush any solid material from clothes, skin, or hair while protecting eyes.
      2. Remove contaminated clothing and flush exposed area for water for at least 15 minutes.
      3. If eyes are exposed, flush exposed or irritated eyes with plain water or saline for at least 300 minutes, removing contact lenses if applicable.
      4. In cases of ingestion, do not induce vomiting. Do not administer activated charcoal or attempt to neutralize stomach contents. Drink 4 to 8 ounces of milk or water and immediately contact poison control 1-800-222-1222 and call 911.

      -Kelsey with Bramble Berry

      • Peter Suthers says

        Thread is a little old now but…..

        MSDS aside, Kaitlyn is correct (I’ve never found any MSDSs that they were too informative and are used to group classes of chemicals in emergency response). I have personally pulled a handful of flesh from my leg when I didn’t realise that some hot caustic solution soaked through my pants (of course until it was too late). I always keep vinegar handy now. You can flush with water until the cows come home and your skin will still feel soapy (why?, because the caustic is literally turning your skin to soap). Use vinegar to neutralise the caustic and your skin will go back to normal straight away. Then wash with water. Experiment with some dilute caustic and you will see what I mean.

        • Kelsey says

          Thanks so much for your feedback Peter! I’m so glad your leg is OK, and that vinegar helped. Safety is definitely important when it comes to lye.

          We recommend flushing the area with water for 15 minutes. I can tell you’ve I’ve spilled both fresh soap and lye on myself, and I’ve found that flushing with water works best. Learn more in the Lye Safety and Ingredients video on Soap Queen TV: https://www.youtube.com/watch?v=yR6ttCSrLJI

          Both the Material Safety Data Sheet and the Agency for Toxic Substances & Disease Registry recommend rinsing lye burns with water for 15 minutes. Specifically the ATSD recommends

          1. Immediately brush any solid material from clothes, skin, or hair while protecting eyes.
          2. Remove contaminated clothing and flush exposed area for water for at least 15 minutes.
          3. If eyes are exposed, flush exposed or irritated eyes with plain water or saline for at least 300 minutes, removing contact lenses if applicable.
          4. In cases of ingestion, do not induce vomiting. Do not administer activated charcoal or attempt to neutralize stomach contents. Drink 4 to 8 ounces of milk or water and immediately contact poison control 1-800-222-1222 and call 911.

          I am so glad that your leg was okay. That sounds like it was quite a spill!

          -Kelsey with Bramble Berry

  6. Christina says

    Like a commenter above, I’m wondering how you go about using both types of lye in a single recipe. I’m going to try a shaving soap in the next few weeks using both but not sure what the deal is. Would I just add both types of lye to the liquid and use the same process from there?

  7. Luzvi says

    I don’t have Potasium hydroxide in hand but I want A liquid hand soap, luckily I have soap batch that I don’t like. I grated them and melt like rebatching then when it turn paste I add boiling water with citric acid the I melt them for 6 hours in double boiler in just hot water below. It turn liquid soap. It’s a bit cloudy not like the normal liqiud soap but I like it, it’s gel well like normal liquid soap too.

    • Rosy says

      dear Beth, there is an online video on Brambleberry which I purchased some time ago, and I finally got the guts to make my liquid soap for the first time with the precious help of Anne-Marie’s video, and it was a TOTAL HIT !!! I’m soooo hooked !! I made the multi-purpose soap that comes in her e-Book and I’m in love with the results !! I’ve been using this soap to wash my dishes and counters and I couldn’t be happier. I hope this helps. It worked FOR ME, BIG TIME !! : )

  8. says

    Thanks for all the helpful info on your site, it is such a great resource! I am in the process of making shaving soap and was wondering what the method is for using KOH and NAOH in one recipe? I read somewhere that I need to use a 60/40 % ratio of the two, any suggestions/tips would be greatly appreciated. Greetings from Sunny South Africa…

  9. kaye kelvey says

    Made castile cold process soap using potassium hydroxide instead of sodium hydroxide by mistake. It finally traced poured in mold and after long time did get it cut with fishing wire, but mushy bars. Hasn’t hardened much. Should I throw them out or is there a way to salvage this soap? Been about 8 weeks since I made them.

  10. Sly says

    Thank you so much for this great information. I got some soap on my temple & cheek in the area not covered by my goggles & mask. I caught the one on my temple right away and immediately wiped it off & sprayed on vinegar, which really stinged & burned – and spread it around too (I should have washed it off more thoroughly).
    I didn’t notice or feel the soap on my cheek until 45 min later, after I finished soaping and cleaning up. I washed it off, but didn’t know that I should continue to wash for 15 minutes. My whole cheek – under where the bit of soap was – burned and puffed up for a week.
    What I could not find on the internet or from friends (non-Soapers) is what to apply to the burned area to help it heal (didn’t see that info here either). I tried Vit E – which burned, Aloe gel – which worked for a few hours before stinging, and I settled on Calendula Gel, which usually does a great job of helping to fast. However, I still ended up with a scar on my face.
    I agree with the first comment about how disrespectful so many Soapers are with using lye – they made me believe that lye burns were no big deal – but they really are!! Lye is dangerous! (On the other side, I am saddened when I read blogs from MP Soapers that are terrified of using lye. They are missing so much fun! I want to say to them to just respect the lye and it will be OK!)
    Thank you again for the great info!!

  11. says

    Whenever making liquid or bar soap we always keep a fine mist spray bottle filled with vinegar nearby as it helps neutralize lye. We spray all containers and tools that come in contact with the lye water solution after use and before washing and it saved me when a jar cracked one time after I added the lye to the water too quickly.

    Thanks for the tips! I too must buy my Potassium Hydroxide in bulk where I live but the humid climate it starting to affect its weight and throw off my recipe such that not all of the oils are saponifying. I now use only 1-3% superfatting rather than my standard 7%. The soap calculator makes this adjustment super easy to do!

    Great post!

  12. says

    Hi, I’m Chilean, excuse me I used the translator. I have had very good experiences using potash. The best results I get glycerin adding lye water to accelerate saponification. My last was potash soap shaving soap soda and potash mixture. I share and thank you very much for the post. Marcela

  13. Barbara D. says

    Thankyou for this! I have been soaping for over a decade now and it makes me cringe when I watch “instructional” videos on youtube from seasoned crafters and they are bare handed or even have toddlers and pets wandering around. Most accidents happen when you get sloppy or over confident.

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