Alternative Method for Making Lye, Part 3

Barefootboy's Recipe and Method for making lye from washing soda and hydrated lime, originally found here. Edited by Tentance.

  • Put 4 ounces of distilled water into two, 2-cup measuring cups (or containers).
  • Slowly add 1/2 oz of the Sodium Carbonate to the water in the first cup and stir. It will clunk up, so you'll need to stir gently but well with each 1/2 oz you add. NOTE There will be some very minor but noticeable heat given off. This is normal. 
  • Add 1/2 oz to the water until you reach 2 ounces. Stir until the mix is clear. There may be a tiny amount that will not mix. This is NOT a problem.
  • Slowly add 1/2 oz of lime to the water of the second cup, stirring with each 1/2 added to mix as much as possible. Continue until you reach 2 oz. The mix will look like a grey white milk shake and there will be some gritty residue especially if you use garden lime. This also is not a problem.
  • Carefully pour the first cup with the 4 oz of clear liquid into the first large container, leaving any non liquid behind.
  • Now pour the second cup carefully into the first large container.
  • The mix will now become an even thicker gray white mix. Allow to separate into a clear liquid and a white/grey solid. This can take 2 hours or more. General rule, if you can let it sit for 24 hrs, do so.
  • Set up your funnel with filter on top of you second container.
  • When the mix has settled, carefully pour off the clear liquid into the funnel.
  • The first 3 to 3 1/2 ounces should filter off rather easily, the last 1/2 ounce will take a bit longer. You can either let the mix sit and separate over time, or put the white semi-solid in the filter and let sit until as much of the liquid as possible filters out. What will be left on the filter paper will be Calcium Carbonate (raw chalk) with lye residue. Dispose of this very carefully.
You should now have 4 oz more or less of at least 50% lye solution. Every batch has had the strength verified by the pH test and has turned out 13 on the scale.
As listed above 2 oz of Soda ash (Sodium Carbonate) to 4 oz of water and 2 oz of hydrated lime to 4 oz of water = 4 oz more or less of 50% lye solution.
Editor's Note: To calculate the amount of homemade lye to use in your soaps with your choice of oils, head over to the SoapCalc website. In field 1, choose NaOH (sodium hydroxide). In field 3, choose Lye Concentration 50%. Adjust your superfat and oil percentages and calculate as usual.
When in doubt, do a small test batch. You can always add more water and "cook" the soap for a longer amount of time in the crock pot or on your survival fire until you obtain the desired consistency. This homemade sodium hydroxide might lend itself more to the hot process method until you become more familiar with it.

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