[Music] the Gat types were direct positive unique photographs made not on paper but made on sheets of copper that had been silverplated the first stage was to make sure the plate was totally clean free of dust grease and highly polished these devices called buffing boards we used so you would take the plate and you would rub it vigorously until it was shining and Polished like a mirror the next stage was to make the plate light sensitive to do this you use one of these devices called a sensitizing box inside here there are two ceramic dishes you would place a a solution of iodide in one place the polished dearo type plate on the surface remove the glass plate so the the vapors from the iodine would react with the silver to make a layer of silver iodide and silver iodide was light sensitive you would expose it po possibly up to 15 or 20 minutes until it was then ready to place in the camera to make your exposure you would place the sensitized plate in a plate holder similar to this you would place this into the back of your camera and then you would make your exposure normally by just removing the lens cap and waiting for the the necessary length of time after exposure in the camera the there was no visible image on the plate it was an invisible or latent image that had to be made visible by exposing it to further chemical treatment for dger types Mercury was used this is a deger type developing box you would place the exposed plate face down in the top of the box in the bottom of a box is a tray of mercury you would place a spirit lamp underneath it would heat the mercur mer y the mercury vapor Rises and then reacts with the silver on the surface of the plate to create an amalgam which forms the visible dear Type image the next stage you had to fix the plate to make sure that it didn't continue to darken when it was exposed to light in order to do that you filled a tray like this with a solution of sodium thiosulfate hypo you would then place the plate in the solution agitated and that would wash away any of the unexposed silver iodite on the surface when the plate had been fixed to prevent it from darkening further it was then washed and ready for the last stage which was known as gilding this is a gilding stand you would place the plate on the top light the spirit lamp to warm the plate and then you would pour a solution of gold chloride and as that evaporated with the heat it would strengthen the image and protect it it would bring out the image and improve it finally you would remove the plate again wash it in distilled water and when it was dry it was ready to be placed into a protective case such as this one for viewing whilst it was capable of making good results it had a major drawback uh there were direct oneoff positives if you wanted multiple copies you either had to photograph the subject again or rephotograph the deger type as oppos to the degot type tolbert's process of the negative positive meant that with one negative you could create as many positive copies as you wished it was with tolbert's process the negative positive process of Photography that the future of Photography lay by the early 1860s hardly anyone was making deot types any [Music] longer