What syringe filter should you use for powder cocaine?

How do you filter shit before you inject it? The only thing I know for coke is to do the following: You get fish scale and only fish scale, so no powder. You do not place the coke on any filthy surface. You get a shot glass you carefully cleaned and sanitized, including finishing off with a sterile wipe. You use a sterile wipe for the areas around your injection sites on your body. You use a syringe to premeasure some water, preferably bacteriostatic water. You place that water in the shot glass. You premeasure the fish scale coke on a high accuracy weight-calibrated scale, like an AWS scale. You then carefully dump this into the shot glass. You then mix around the contents with the tip of the needle. You then use a new syringe and pull the contents into it, then you put on a new needle before placing a tourniquet over your limb, inserting, drawing blood, and injecting.