When you measure your liquid wax into your pyrex glass you need to weigh it rather than look at the 8 oz measure on the side of the cup. Same is true for your FO. So take your pyrex cup, put it on the scale and tare it (zero out the weight). take another cup and scoop your liquid wax out of the pot and into your cup on the scale until you have 8 oz in weight on the scale. measure your FO the same way and add it to your liquid wax. hth