new reagents have become somewhat diluted?
One of the biggest differences between hand and machine staining is how the surface tension of the reagent currently on the slide is broken and then replaced by the next reagent. When we stain by hand we exert much more and varied force than a machine does when plunging the slides into the reagent. We also knock off more reagent, so less of the reagent clings to the slide with each move. A stainer (machine, not human) simply lowers the slides slowly, in a single plane, into the reagent. Even the agitation of the machine staining is in that single plane (up and down) movement. When we stain by hand we cause the reagent in the dish to bombard the slide from several angles and with greater force that breaks the surface tension in less time than it takes a machine can accomplish. Therefore longer exposure times (of tissues to stain) may be required on a machine to yield the same results as hand staining. When programming the machines I find it necessary to watch the hand staining carefully
One of the biggest differences between hand and machine staining is how the surface tension of the reagent currently on the slide is broken and then replaced by the next reagent. When we stain by hand we exert much more and varied force than a machine does when plunging the slides into the reagent. We also knock off more reagent, so less of the reagent clings to the slide with each move. A stainer (machine, not human) simply lowers the slides slowly, in a single plane, into the reagent. Even the agitation of the machine staining is in that single plane (up and down) movement. When we stain by hand we cause the reagent in the dish to bombard the slide from several angles and with greater force that breaks the surface tension in less time than it takes a machine can accomplish. Therefore longer exposure times (of tissues to stain) may be required on a machine to yield the same results as hand staining. When programming the machines I find it necessary to watch the hand staining carefully
