It needs to be bigger than .5mm since you have to squish it down. I'm not for sure what size I have been using. It measures about 1mm-1.5mm thick. Also make sure it's soft lead solder.Indsk8 said:what size of solder did everyone use for the quench measurment. i read .5 mm but i cant find .5 mm i can find nothing but .050 inch.