If you love cold process soap making but want to try something different, why not try hot process soap making?
You may not have heard of hot process soap as it is not as popular as other soaps, but it has been around for centuries.
It uses a completely different method to cold process soap making. So if you want a new challenge, this soap is for you.
Hot process soap making may have gone out of fashion, but we love it and we want to show you how good it really is!
Contents
- What is Hot Process Soap?
- Why Make Hot Process Soap?
- What Drawbacks Are There?
- Soap Making Safety
- Hot Process Soap Making Tips
- Easy Hot Process Soap Recipe
- Final Thoughts
What is Hot Process Soap?
Hot process soap uses natural oils, water and sodium hydroxide to make a solid soap bar. Unlike other soap methods, this one involves cooking the soap in a slow cooker above 50°C.
It is a more forgiving way to make soap, but the soap does look a little rough around the edges.
Why Make Hot Process Soap?
Hot process soap is not as popular as other soap making methods, but it is a great alternative to cold process soap making. It is good for sensitive skin types as it uses natural oils and only a few ingredients.
It is also a much more forgiving method compared to cold process soap making. Hot process soap can technically be used after the soap has set and as it has a much shorter cure time than cold process soap making. However, we would still recommend curing it for a few weeks.
What Drawbacks Are There?
The most noticeable thing about hot process soap is how it looks. The soap bars do come out rough and rustic and it is hard to make them look nice.
This soap making method does involve using sodium hydroxide so you will need to be careful. As long as you follow the appropriate safety precautions, it is safe to use.
One big thing to note when making hot process soap, is you need to get a slow cooker that is for soap making only. You cannot use a slow cooker than is used for food, so you will need to purchase a separate one!
Soap Making Safety
Hot process soapmaking does involve handling sodium hydroxide and essential oils which are hazardous substances. But if used correctly and carefully you will be fine!
Sodium Hydroxide
Pure sodium hydroxide is a highly caustic substance that must be handled carefully. Contact with the skin will cause severe skin burns, and the inhalation of vapours can cause irritation. Keep out of reach of children and pets.
When handling caustic soda, make sure to follow the appropriate safety precautions. You must wear gloves, a mask, safety goggles and long-sleeves. Also ensure you are working in a well-ventilated room (so open a window), otherwise you may need a respiratory mask.
When adding caustic soda to water it can become quite hot and the fumes can be quite unpleasant, so ensure the room is well ventilated and do not directly breath in the fumes.
Never add water to sodium hydroxide, always add sodium hydroxide to water. This helps prevent overheating and splashing of highly concentrated sodium hydroxide.
Make sure you don't mix your soap making tools with food preparation tools. Your soap making tools will have caustic soda residue on them and need to be washed thoroughly before they are safe to handle. But you won't want to cook with them!
Essential Oils
It is important not to apply them directly to the skin or ingest them. When handling essential oils, we recommend wearing gloves. If an essential oil makes contact with your skin, wash it off with soap immediately. For more information on essential oils for soap making, click here.
Hot Process Soap Making Tips
Hot process soap making can be a little intimidating at first, but it is actually more forgiving than cold process soap making.
However, there is still room for error. So here are a few things we’ve learnt along the way…
Equipment
When making hot process soap, you need to buy new equipment specifically for soap making. So don't be tempted to use the slow cooker you cooked dinner in!
So what do you need?
- 3.5L slow cooker
- Gloves
- Goggles
- Digital weighing scales
- 2 x 1L plastic jugs
- Silicone spatula
- Digital thermometer
- Immersion blender
- Soap mold or DIY alternative
Trace
Trace is the point where the oils and sodium hydroxide solution have fully combined. It occurs when you are blending the ingredients all together.
To test if the mixture has reached trace, you can drip some of the soap mixture back into the bowl of mixture. If it sits on the surface before sinking back in, then it has reached trace.
In hot process soap making, you want to create a light trace or medium trace.
Temperature
One of the main things to be mindful of with hot process soap making is the temperature. You want the melted oils to be below 65°C, and the sodium hydroxide solution to be below 26°C.
Make sure your slow cooker is on low heat when you're cooking the soap, and you won't go far wrong. If the heat is too high, the hot process soap might boil over like boiling milk.
You may find some of the soap mixture sticks to the side of the slow cooker. If you notice it early and it's still liquid, mix it back into your mixture. If it has hardened on the side, leave it there as it won’t melt and you’ll have lumps in your soap!
Your slow cooker will be on for many hours, so we recommend adding the essential oils at the end!
Curing
Curing is when the soap is left for a few weeks or months to harden. It also ensures there is no sodium hydroxide present in the soap.
Hot process soap doesn’t technically need to be cured as it is safe to use once set. However, we would still recommend curing it for a few weeks to allow the soap to harden and last longer..
Easy Hot Process Soap Recipe
This recipe contains 20% superfat. Find out more about superfat in soap here
Ingredients:
- Coconut oil 900g
- Water 297g | 297ml
- Sodium hydroxide 132g
- Orange essential oil 24g | 28ml
Method:
1. Make the sodium hydroxide solution
- Put your gloves and safety glasses on
- Open the window, the fumes will be unpleasant
- To make the sodium hydroxide solution weigh the sodium hydroxide in a bowl and the water in a separate bowl (ensure you follow the safety requirements first)
- Pour the sodium hydroxide into the water, not the other way around! Mix well until the sodium hydroxide has fully dissolved
- Leave to cool down, it will be hot
2. Weigh out the coconut oil
- Weigh your coconut oil and add it to a slow cooker.
- Switch on the slow cooker and heat the coconut oil until fully melted.
2. Check your temperatures
- When your coconut oil has melted, check your temperatures. You need your coconut oil to be below 65°C and your sodium hydroxide solution to be below 26°C
- When you are happy with your temperatures pour your sodium hydroxide solution into your coconut oil in your slow cooker.
3. Blend until trace
- Stir gently with your hand blender and then blend until it reaches a light to medium trace. Hot process soap making is very forgiving, if you blend too much it will not matter.
4. Cook the soap
- Put the slow cooker on low and cook the soap mixture.
- Your soap will go through different stages, a solid waxy substance and then begin to soften and gel until it resembles a thick mashed potato texture with a glossy, Vaseline like sheen.
- Do not overcook, if in doubt you can check your soap with a pH strip. You are looking for a pH of around 10.
- Remove your ceramic cooker dish from the slow cooker and add your orange essential oil.
- Mix the essential oil in well until fully combined.
- Leave the soap to cool until it is below 80°C.
5. Mould your soap
- Scoop the soap mixture into your soap mold and tap on the worktop to fill air pockets.
- Try to smooth and level the surface as much as you can. Don't worry if it is still a little rough, this creates bars with a lovely natural look. You can always trim it off if you don't like it.
6. Cut and cure
- Coconut oil soap sets very fast. After 2 - 3 hours while the soap is still warm, cut the soap into equal sized bars.
- Put the solid soap bars with gaps in between them, and let the soap cure for about 4 weeks.
Final Thoughts
I know hot process soap is very different to other soap making methods, but with practice you will love it!
Once you've mastered hot process soap making, you can find some more recipes here!
Want to learn how to make cold process soap or melt and pour soap? Check our our complete beginner guides:
Continue Reading
Now you know how to make soap, why not learn how to make other cosmetics?
- Want to try more hot process soap making? Try our oatmeal soap recipe!
- Looking for a melt and pour soap recipe? Take a look at our goat's milk melt and pour soap recipe here!
- Ready to try some cold process soap making? Try our mango butter soap recipe!
How did your handmade soap turn out? Comment below and let us know!
