I'm using Kester R520A Lead free solder paste. The flux % stated on the Certificate of Analysis(COA) when the product delivered to us is 10 %. The tolerance is 1%. But when i send the jar to an external lab to determine the flux % it is more than 11%, whereby it should not be more than 10.5%. According to Kester, the figure stated in the COA is the amount mix with the solder powder. Moreover, there will be chemical reaction between the activators in the flux & Tin (Sn) which will results in increase amount of flux. The increase is called a correction factor which we need to add up to the number in COA. The correction factor range from 0.5 to 0.8%. Does anyone have any idea about this? By the way, I am trying to reduced the flux% in order to reduced the solder splattering. Will this work?