In order to prepare beer for soap making, you must remove the alcohol from the beer to avoid a volcano in your work space. Leaving the beer out for 24 hours will do the trick, but fungi may be an issue before long. The fastest way to do this is by boiling the beer for a short amount of time. This usually takes approximately 15 minutes.
Next, let the beer cool on the stove for a bit and pour it into ice cube trays for freezing.
Freeze the beer overnight and remove it the next day. Once it is completely frozen, remove the ice cubes from the tray and place them into a plastic freezer bag until ready to use.
How to Add Lye to Beer
When using the frozen beer, first weight how much is needed in the soap recipe. Use another bowl with ice and cold water as an ice bath for our lye container. This will make sure the beer doesn't burn when the lye is added.
Then, slowly add the needed amount of lye for your recipe and stir, stir, stir until the lye and beer are completely mixed and there are no clumps. The lye and beer should not reach above 70 degrees F. If the temperature gets much higher, the beer may burn.
Once all oils are melted and combined for the recipe and both the oils and lye solution is 70 degrees F, carefully add the lye solution to the oils and continue with the soap recipe as usual.