when i have a batch ready to process, i do a tit test and work out what cat is needed.
I then take a 1.5 ltr plastic bottle add 1 ltr of the oil then heat in the microwave to 50c ( make sure the Mrs don't see) add the metoxide and give it a good shake and leave for an hour.
then you do a 27/3 test on the bio that has been released.
this should give you an idea if your calcs are right. you can add another gr of cat if not fully converted shake and wait and so on. if you get a bottle of soap, then to much has been used, start test again using less