Perhaps this will help, Carl:
https://www.mariegale.com/calculating-net-weight-soap-part-1/
https://www.mariegale.com/calculating-net-weight-soap-part-2/
https://www.mariegale.com/calculating-net-weight-soap-part-1/
https://www.mariegale.com/calculating-net-weight-soap-part-2/