Temperatures for Soap Making (cold and hot process)
Hi everyone, many of you have requested a video on the topic of soap making temperatures, and I’m very pleased to finally deliver! Thanks so much for your patience if you were waiting for this one, I'm slowly making my way through my list of videos 'to do'.
Please click on the image above to go directly to Youtube to watch the video.
In the video I discuss:
Why I don't take the exact temperature of my oils and lye for many of my soap recipes.
When it is important to use a thermometer (or otherwise gauge the temperature) in cold process soap making, including an explanation of 'False Trace'.
An explanation and some tips about using the 'Heat Transfer Method' in cold process soap making.
A simple approach that will work for most soap recipes if you aren't sure.
How I gauge the temperatures in my soap recipes (high and low tech).
My approach to temperatures for hot process soap making.
A summary of the important points…
Why I don’t take oil or lye temperatures for most of my soap recipes
The main reason for this is that most of my soap recipes are made with very high amounts of liquid oils, which are unsaturated fats and liquid at room temperature. Examples of these include olive oil, rice bran oil, sunflower oil, castor oil, coconut oil (in warm climates), almond oil etc. These liquid oils have no chance of solidifying in contact with a cool/room temperature lye solution and therefore it is unnecessary to be exact about the temperatures of oil or lye for these simple recipes. Any room temperature is usually fine for making soap with these types of oils.
What is ‘false trace’?
False trace is the term given for thickening of the soap batter when it contains saturated fats or ‘hard’ oils and these solidify (to varying extents) in contact with a lye solution that is too cool. When false trace occurs, the soap batter often becomes grainy in appearance and can thicken prematurely, mimicking a genuine trace. If you think this has occurred in your soap batch, continue mixing the batter until the exothermic (heat-generating) saponification reaction begins and the solidified fats re-melt and return to a liquid state, after which the batter can continue to be mixed until a genuine emulsification and trace are achieved.
Avoiding False Trace
If you are using soap recipes containing ‘hard’ oils and unsaturated fats, particularly those with very high melting points, check the melting points of your ingredients and ensure your oil mixture is completely melted and homogenised before you make the soap (it should be liquid and transparent, not cloudy). Then ensure that your lye solution is not too cool - around body temperature or a bit higher 40°C / 100°F will be warm enough to prevent false trace in most soap recipes.
Recipes that contain high amounts of beeswax and other ingredients with very high melting points (best to keep these in low amounts, 1-2% for waxes) may need to be kept warmer and mixed with a warmer lye solution to prevent solidifying. Up to 50°C / 122°F would be suitable for recipes containing very hard fats and waxes, however, the oil mixture may need to be melted to a higher temperature than that initially to melt all of the ingredients.
Examples of melting/solidifying points for some common soap making oils/fats/waxes (approximate values):
Olive oil -6°C / 21°F
Canola oil -10°C / 14°F
Sunflower oil -17°C / 1°F
Almond oil (sweet) -18°C / 0°F
Coconut oil 25°C / 78°F
Palm kernel oil 25°C / 74°F
Palm oil 35°C / 95°F
Cocoa butter 35°C / 95°F
Shea butter 35°C / 95°F
Lard 35°C / 95°F
Tallow 40°C / 104°F
Beeswax 65°C / 149°F
Candelilla wax 70°C / 158°F
The Heat Transfer Method
The heat transfer method is commonly employed by cold process soap makers and utilises the heat of a freshly made, hot lye solution to melt the soap making oils. This method works very well with recipes containing a combination of soft/liquid oils and low to moderately hard oils such as coconut oil, palm oil, lard/tallow and some butters. In this method the oils are weighed into the soap making jug or bucket, after which the lye solution is mixed and poured directly into the oil bucket without delay. The soap mixture (oils and lye water) are then stirred gently until all of the oils are melted, after which a stick blender can be used to bring the soap batter to trace.
If you would like to use the heat transfer method, consider the oils you would like to use and their melting points - they may need additional help to melt, especially if your room temperature is cool. Also consider the water level of your soap recipe which determines the volume of your lye water solution - low water recipes with small volume lye solutions may not have enough heat to fully melt some oil combinations. This is fully explained in the video.
My general guide
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.
Temperatures are not crucial for liquid oil recipes and those which contain minimal amounts of semi-solid fats when made in warm conditions.
Temperatures for hot process soap making
Due to the nature of hot process soap making in which the saponification reaction is forced through the addition of extra heat, there is less concern required for the temperatures of oils and lye in the process.
I recommend warming and completely melting your oils together in the soap cooking pot/crock pot before adding the lye solution and blending. It is not necessary (in my opinion) to cool the lye solution prior to mixing with the oils in hot process soap making. Adding hot lye to warm oils serves to accelerate the saponification reaction which is the desired effect of this soap making method.
Thanks everyone, I hope that was helpful. Please let me know if you have any questions or you would like me to add any further information.
Please also consult my soap making terms page for more in-depth explanations of many of the terms used in this article.
Happy soap making! 🌿
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