1. What is the reason for placing the jars with bark in boiling water for 1.5 hours each wash? What does it do?

2. Is there benefit to doing a naptha wash before basifying to defat?

3. When adding naptha, where it says "While the liquid is still warm add 600ml of naptha cap the jar and with gloves and goggles on shake it over a sink vigourously. do this 6-10 times"

Does this mean shake and let it settle 6-10 times, or shake with fresh naptha 6-10 time, which would mean with up to 6L of naptha?

I don't understand how letting it settle before shaking again would help things. Also, a gentle rotation should absorb the alks fine, without creating an emulsion mess to deal with. Can someone clarify why it should be done so?