Sensitizing the Plate

Before it can be exposed in the camera, a collodion plate must be sensitized in a solution of silver nitrate.

This is done by dipping the newly coated plate into a 7% silver nitrate bath. Do this with confidence, lowering it smoothly and evenly into the tank. This should only take 2 or 3 seconds to accomplish. Don't splash or disturb the solution any more than absolutely necessary and don't hesitate while inserting the plate into the liquid. Hesitation can cause lines in the image later on. Once the plate is in the silver nitrate, close the lid of the tank and wait approximately 3 minutes.

While the plate is soaking in the silver bath, this is a good time to prepare your materials for development. Set out a tray large enough for your plate, a beaker or wide mouth jar of distilled water to stop the development, and a small beaker (50ml) to hold the developer. Pour out a sufficient amount of developer to cover the glass plate (for example a 5x7 inch plate would require about 10 ml of developer).

After approximately 3 minutes, pull the plate from the silver nitrate bath in the same confident manner in which it was inserted. Again, avoid hesitation. Look at the surface of the plate as you're pulling it out. If you see an oily appearance with rivulets running off, the plate needs to be reinserted into the silver nitrate for a while longer. If the silver nitrate flows smoothly off the surface when it's removed from the tank, it's ready for the plate holder.

Once the plate has been removed from the bath, allow the bulk of the liquid to drip back into the tank. Place a clean dry paper towel on the darkroom bench and rest the edge of the plate on the paper. Blot the excess silver nitrate from the edges of the plate by rocking the plate forward and back slightly. Repeat the procedure on the adjacent edge. Continue blotting these two edges until the towel no longer shows wetness. Remember, when you hear the term wet plate, think moist plate. Insert the plate in the holder with the collodion side toward the dark slide (usually down). Gently wipe the back of the plate with a dry towel to remove any excess silver. Close the plate holder door and lock. You now have a sensitized plate ready for exposure.