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Cold Process Soap 101

Cold Process Soap 101


Once you have all your ingredients and equipment prepared, you can begin the lye soap making procedure.


Make sure that you are wearing your rubber gloves and goggles. Don’t take them off until you are completely done with all the cold process soap making steps!


Step 1: Making your Lye Solution


First, prepare the lye solution by mixing the carefully weighed dry lye according to your recipe with the appropriate amount of water.


Never use hard water for cold process soap making because the unwanted substances within the water could take part in the reaction. You can have your tap water tested for hardness at a local appliance store or simply purchase distilled water from the store.  Purchasing distilled water will provide you with more consistent results.


Measure out the dry lye in a small Ziploc bag or a container with a lid so that you can safely seal it in case of interruption. Be sure to make your lye measurement exact! Remember to always pour the lye into the water, not the water into the lye!


Mix the lye and water combination continuously until all the lye is dissolved. Remember that the reaction will cause the solution to heat to more than 200 degrees Fahrenheit; be careful that your container that can easily withstand that type of heat!


How much water should you use? Check your recipe, but as a general rule, use an approximate 1/3 lye to water ration.  3 ounces of water for every 1 ounce of lye.


The water molecules do not actually take part in the cold process soap making reaction, but merely serve as a solvent. If only dry sodium hydroxide is used, it won’t all be able to interact with all the oils or fats in the recipe. The addition of water allows an equal spread of the sodium hydroxide throughout each ingredient.


Note: Too much water can cause the soap to become soft while too little water can cause the soap to become caustic and dry.


Congratulations, you’ve made your lye solution.  Now insert one of your two soap making thermometers into the liquid and carefully place the mixture to the side for later use. Be sure to keep it in a safe area away from children, pets, or anyone else.



Step 2: Prepare the acid


First pour the appropriate weights of the oils or fats into the large soap making pot. At this point, Make sure that you only insert the liquids.


Next, place the correct weights of your solid fats or oils into the 3 quart saucepan and melt to liquid form. Add this to the other liquid oils in the large pot.


Remember to always measure all your ingredients by weight.  For the best results and consistency, all measurements need to be exact. With not enough fats or oils, the soap will be caustic as there is leftover lye that has not taken part in the reaction. With too much fats or oils, the soap will become extremely soft as there will be unadulterated acids that could not react with any lye.


Most soap makers purposely add extra beneficial fats and oils to their recipe for the added skin care effects of these oils in non-saponified form. This is called super fatting or lye discounting. As super fatting on your own is a more advanced and delicate technique, just remember to follow the recipe exactly when first starting out. Pretty much all recipes are already super-fatted for you so that there’s no risk of extra lye in your soap.


You can also add a natural preservative (antioxidant) like grape seed extract to the fats and oils mixture before moving forward.


Now insert your second thermometer into this concoction and place to the side for future use.


You should now have one container with a lye and water mixture (the base), and one container with the oils, fats and optional preservative (your acid).



Step 3. Getting the Temperature Right


Now wait till both mixtures drop to the recommended temperature. Most soap recipes will indicate what temperature to mix the lye with the fats and oils, but remember that this part of the cold process soap making method is pretty subjective.


95 degrees Fahrenheit is usually perfect for castile soap or any other all vegetable oil soap. For soaps made with animal fats like tallow and lard, it is recommended that you combine your ingredients at a higher temperature somewhere around 110 degrees Fahrenheit.  In the beginning follow whatever your recipe says.  Ultimately, you may want to experiment with different temperatures.


It is possible that the two mixtures will hit the desired temperature at the same time, however, you will probably need to adjust the temperatures to get them just right. You can warm up either solution by inserting the container into hot water or cool it down by inserting the container into cold water until the temperatures are equal. This can be done right in the kitchen sink.


Step 4: Mixing the Ingredients



After the desired temperatures are met, slowly pour the lye into the oils and fats mixture while stirring vigorously. Note: You can transfer the lye solution into a Pyrex measuring cup to make it easier to slowly pour the chemical into the oils. If you do this, make sure that the lye has cooled down substantially so as to not risk breaking the glass with the hot lye/water solution.


This is the most important step in the cold process soap making procedure.  In order for all the necessary molecules to interact, make sure that you stir the mixture briskly and constantly.  You can also use a powered stick blender.


In order to test if saponification has occurred and your soap mixture is ready, drizzle some of the soap on your spoon onto the top of your mixture.  If the drizzled soap sits on top of the mixture briefly before sinking down, then your soap is ready.  This stage is called Trace.


Keep on mixing until you reach trace… this should take 45 minutes to 1 hour for most cold process soap making recipes if stirred manually, but keep in mind that the time it takes for the formula to saponify may vary drastically. If a stick blender is used, trace can sometimes occur in as little as 2 minutes!



Step 5: Additives


After trace is reached, add the essential oils or fragrances and other various nutrients. Be creative, or do as the recipe calls for. At this point, you can also add your soap making dye. Stir well until everything looks even toned.


Step 6: Soap Molds


Pour the soap into your choice of soap making molds. There are a lot of choices here, everything from PVC pipe to elegant decorative shapes. Wooden loaf molds are a great choice, but find what you like; it is all part of the fun!



Step 7: Insulating Your Soap


Cover the mold with its lid (or a piece of cardboard) and then wrap it with towels. You can never insulate your soap too generously!  Typically, 6 – 8 towels should be perfect. You want to make sure that no heat can escape, as this is very important for the initial curing process.


Now leave the soap for about 18 – 36 hours depending on the ingredients used. Once again, reference your recipe for instructions on how long to allow the soap to cure before cutting.



Step 8: Finish Curing


Once the soap has somewhat solidified and hard enough to slice, carefully measure and cut it into equal bars. If needed, trim and carve the soap until the desired shape is formed.  If you used individual molds, remove the already formed soap bars.


Lay the new soap on a rack so that air can circulate around it. Flip them over about once every 6 – 8 days. The soap will now need to cure for 3 – 8 weeks depending on the recipe. During this time, the soaps PH level will remarkably drop and your finished product will be wonderfully mild and natural homemade soap. Before you use your soap, be sure to scrape off any white powder (soda ash) that formed on the top of the bars. This substance can dry skin.



Cleaning Up


Remember to label your supplies “soapmaking” and keep this equipment separate from all your other kitchen supplies.  Even if you are careful with your cleaning, you should not use them for cooking.

Wash everything by hand. Don’t use the dishwasher, because the leftover soapy residue can cause it to leak! This will also help avoid contaminating other kitchen utensils with the harmful lye.

Finally, be sure to store all extra supplies (especially lye) in a safe area away from children and pets.