The ideal consistancy for a scrim cloth for leaded is to wet it in clean water (no soap)
Then wring it out until your knuckles turn white, If you have not got a great grip loop it around your ladder style and keep twisting at least until no more water comes out of it, I find this method the best for leaded.
Scrub with your now damp scrim ,go over every bit of glass at least twice remember to keep turning the cloth if it gets dirty then quickly as fast as you can buff up with a dry scrim.
Just experiment until you find what suits you, I could never get on with micro fibre myself, but a lot here seem to have no trouble with it, Maybe because microfibre was not around when i started out and had to learn to use scrim correctly, but once you have mastered it, it will be your best friend.
Micro fibre or scrim the choice is yours
Dave