Fu Rui first mixed the wood ash with a certain proportion of water, then used something to filter out the impurities and gray matter.
There was no filter, and the conditions did not allow for production of a filter. Thus, Fu Rui could only use his T-shirt as a filter.
It just so happened that it had just been washed by Yuan. Thus, he could simply use it as a filter.
After this treatment, the mixture of ashes with wood and weeds became the most primitive and natural alkali liquid.
However, this wasn't enough to make soap. The concentration of alkaline had to be increased, so Fu Rui continued to heat the mixture up. Then, he would determine if the concentration was up to standard when an egg could float in the water.
After that, he took out the lard that he had collected earlier and added it into the alkali water bit by bit. He stirred it continuously and waited until it turned into soap.
