Collodion process / Wet plate process
A Collodion process also known as a wet plate process is a personal favourite of mine. Invented in 1851 it requires the photographic material to be coated, sensitized, exposed and developed within the span of about fifteen minutes, necessitating a portable darkroom for use in the field. The collodion process produced a negative image on a transparent support (glass). We can achieve a similar version digital using Photoshop. I've used a picture I took in the studio a few years ago. I would advise taking a portrait of someone with interesting features, a more 'mature' looking person works well because of the contrast range in the wrinkles.
1. Apply High Pass sharpening
Open your portrait image in Photoshop and press Ctrl+J to copy the Background to a new Layer. Next go to Filter>Other>High Pass and set the Radius to 10 Pixels for a head and shoulders shot, or 5 Pixels for a waist level portrait. Now go to the Layers panel and click on the Blending modes dropdown menu at the top that’s set to normal by default, and select Overlay from the list of options.
2. Add Lens and Movement Blur
Hold down Ctrl+Shift+Alt+E to merge the visible Layers into a new Layer at the top of the stack. This will now be active. We need to do this because adding blur to the previous Layer will not show up. Next Go to Filter>Blur>Lens Blur on the main Photoshop menu and use all of the default settings except for Radius, which should be set to 60. Click OK. Go back to the menu and click on Filter>Blur>Motion Blur. When the dialogue box opens set the Angle to 10, Distance to 50 and hit OK.
3. Mask out an area of blur
Click on the Layer mask icon at the bottom of the Layers panel to Add layer mask – it’s the icon showing a rectangle with a circle in the centre. Press D on the keyboard to set the foreground and background colours to black & white. If white appears in the foreground hit X to switch to black. Now press B on the keyboard and select a large soft edge brush (around 1500 px) to mask out blur over the central part of the face. If you make a mistake press X to bring white to the foreground and paint over the offending area. Take time when doing this because what you’re aiming for is a believable shallow depth-of-field effect.
4. Convert to black & white with the Channel Mixer
Click on the adjustment layer icon at the bottom of the the Layers palette – it’s the half- black half-white circle. Select Channel Mixer from the list of options. Next check the Monochrome box to convert the image to black & white. Now it’s time to create the highly detailed skin effect, so as a starting point set Red to -100, Green to 0 and Blue to 200. Now move the red slider to the right until the image is as bright as you’d like it to be. If highlights are blowing out drag the Green slider to the left. My final settings for this portrait were Red -56, Green -22 and Blue 200. All images are different so you’ll have to experiment on an image by image basis.
5. Lighten and dull the image
Go back to the adjustment layer icon and select Curves from the list of options. Left mouse click in the centre of the curve and drag up and to the left slightly to lighten the image a touch more. Hit OK when you’ve finished. Click on the adjustment layer icon again, and this time select Levels. Set Output to 10 for blacks and 220 for whites. This will dull the image slightly to give it a more authentic look.
6. Select and Copy a texture
Now it’s time to mimic the smudged emulsion effect typical of the wet plate collodion process. Open your texture image and convert it to black & white if it isn’t already. Next hold down Ctrl+A to Select All, then Ctrl+C to Copy. Click on the tab for the portrait image and press Ctrl+V to paste the texture onto the image. Go to the Blending modes menu on the Layers panel and select Multiply from the list to add a degree of transparency to the Layer.
7. Duplicate the texture and change Blending modes
Hold down Ctrl+J to make a copy of the texture Layer, and then press Ctrl+I to invert it. Now go to the blending modes menu and select Screen from the list. Press V on the keyboard, then left mouse click and drag the layer so the two textures are skewed. Hold down Shift and left mouse click on the texture Layer below so both textures are now selected. Press Ctrl+G to group the Layers, and reduce Opacity to around 70%. You can do steps 6 and 7 multiple times with different textures.
8. Sepia tone the image
Go to image / Adjustments / Photo Filter... When the dialogue box opens click on the dropdown menu that’s set to Warming filter (85) by default and select Sepia. Drag the Density slider to the right until it’s set to between 20 – 50% This will give the image a natural warm look. The wet plate collodion effect is now complete. You can now keep all the Layers intact or Flatten the image go to Layer / Flatten Image.