Depending on the size of the print you might find it convenient to switch to cc. 20 drops normally make up one cc. When measuring, just use a beaker with an exact cale, and watch the surface of the fluid exactly (it will be somewhat concave, and it is worthhile to take this into account. Also, I would use a few drops of water to "clean" the beaker afterwards, and get out any precious metal left back in it. This will somewhat dilute the sensitizer, but that won't matter.