Daguerrotypes are an old type of photograph which were produced on a silver-coated copper plate, giving a mirror-like finish. True daguerrotypes need unpleasant chemicals but I tried to find a different technique to make unique pictures which appear to be on a metallic background.
A few years ago, I found a box of glass photographic plates. Strictly speaking, they are autoradiographic plates (Kodak AR.10), designed to image radioactive emissions from plant and animal samples which had been injected with radioactive markers. There are more-or-less the same as X-ray plates. Fortunately, they are also sensitive to light and work like a normal photographic plate. There’s no date on the box but they look several decades old and are quite fogged.
Usually, glass plates are exposed in a camera to form a negative which is then printed onto paper in a darkroom to form a positive image. But there’s nothing to stop you using a darkroom enlarger to print an existing negative onto a glass plate as a positive, which is then transparent.
I chose to print a medium format negative of my daughter onto this glass plate, which is 4¾×6½” in size. This negative was originally taken with a Mamiya C220 and Sekor 80mm f/2.8 lens. I chose to crop the square negative into portrait orientation, like most daguerrotypes.
It took a few experiments to get the right exposure on the plate, which is very slow (and long expired). In the end I settled on an exposure of 45 seconds with the enlarger lens set to f/5.6. For comparison, exposing a 5×7″ paper print would probably take 10 seconds at f/16. If I’ve done my head-calculations right, that means the plate is five stops slower, with an effective ISO speed of about 1/32 (0.03). So these plates might not be suitable for high-speed sports photography.
I developed the plate in ordinary paper developer (Ilford Multigrade developer) for 90 seconds, just like a regular print. I treated the plate as usual with regular stop bath and rapid fixer. There was a nice strong image there, although not as high contrast as you’d get from modern paper. To try and blacken the dark area and boost contrast, I toned the plate in Harman selenium toner for about a minute, although I had to stop because it was turned the plate more brown, rather than black. After a quick dunk in a bath of wetting agent (Ilfotol) to prevent drying marks from the hard water, I left the plates to dry.
So this gives a positive image on a glass plate which can be put in a backless frame to be backlit by a window or an artificial light source, but I wanted to create something that looked like a daguerrotype. My first idea was to try sticking a piece of aluminium foil to the back of the frame. This plan was “foiled” because the brand of foil we normally use has a strange diamond pattern pressed into it.
Fortunately, the cheap-o-nasty foil is smooth so I gave that a go. The only glue I currently have that dries transparent is PVA glue. It’s not the ideal thing but it will probably do. I expect it will take ages to dry because neither the glass plate nor the foil allow evaporation. I spread the glue with a brush and then squeezed out bubbles and excess glue by smoothing the foil without creasing it.
The emulsion side of the plate must be the side touching the foil, otherwise you get ghosting (you can see this in the picture of the plate being washed). This also means the delicate emulsion is protected. It also means the image is flipped left-to-right, as daguerrotypes always were.
Turns out that my hunch about the PVA glue not setting was correct. After waiting for more than a week, the glue was still wet and was clearly not going to set any time soon.
PVA glue is soluble in water though, so I decided to peel the foil off and wash the glue off in water. The glue had dried in a few places around the edge and it damaged the gelatine emulsion. The rest of the glue washed off in tap water in a few minutes and then I washed the plate in Ilfotol again before leaving to dry. Back to square one (and with a little damage).
I don’t have any other glues at home at the moment, so I decided to take a different path. I painted the emulsion side of the plate with silver spray (supposed to be for my car).
This does not give a mirror finish – it gives a glittery metallic finish, like a silver car. However, viewed from the front it is sufficiently shiny to look a bit like a metal plate. After a couple of coats of paint, I applied a couple of coats of clear lacquer to the back to give some protection.
Last but not least, I cut a custom mat to mount this unusual 4¾×6½” glass plate in a more typical 5×7″ frame. I discarded the original glass from the frame because the glass plate obviously comes with its own glass. The emulsion is on the back and is protected. Here’s the finished result.