Pour all the liquid soap concentrate base into the large heat-proof bowl and microwave on 30-second bursts it until it’s about 140F. Using a dropper, add 8 mL of fragrance oil. Stir until the base turns clear, periodically spritzing with alcohol to pop any bubbles. If the soap isn’t clear after a few minutes, microwave on 10-second bursts and stir until it is.
Place the large bowl on a scale, weigh out 37 oz. of distilled water, and mix. Spritz with alcohol. Add all of the Optiphen ND. Using a dropper, add drops of blue colorant up to 2 mL until you get a shade you like. Stir to fully incorporate.
Using a funnel, carefully pour the soap into the foaming pump bottles, leaving a ¼” of space at the top. Let sit for an hour without caps to cool. Screw the caps on and enjoy.
Recipe by Soap Queen at https://www.soapqueen.com/bath-and-body-tutorials/foaming-liquid-soap-kit/