I have recently just finished my second stint as a science communicator at the Edinburgh International Science Festival, which was a great experience once again. This year was a special anniversary for the festival as it celebrated a quarter of a century, bringing science to the kids and general public of Edinburgh. Although I do not remember it, apparently I visited the science festival as a child, when the main attraction was some new invention called the internet. What ever happened to that?
Anyway, the event I was running was a simple Tin Box Camera workshop. All that was required was a camera, obviously, a bright spotlight and a dark room full of chemicals. The kids or parents would strike any pose they wanted, with the more extravagant the better, though the catch was to hold it perfectly still for 30 seconds. The cool thing about these was that you could produce double exposure photographs, which resulted in a lot of fun pictures. For example you could have two separate versions of yourself shaking hands with one another, or have a ‘ghost’ of someone in the background if they were in the picture for just 10 seconds. Some of my many attempts are below….
One thing you have probably noticed is that they do not look like much of a picture. That is because they are negative images. When displayed through an inverse setting on a camera they look a bit more lifelike……..
The science behind producing these photographs is interesting. The paper we used was covered in a silver bromide coating, which when hit by light produces a chemical reaction that gradually turns the paper a pink/purple colour. This is why an exposure of only 30 seconds was needed. Once in the dark room our photograph was put through 3 chemicals: hydroquinone for the developer, acetic acid for our stop bath and ammonium thiosulphate for our fixer.
A fun thing to wind up some of the kids was to ask if their photograph had worked, as all they would have when they took their photograph from the camera was a blank bit of paper. Of course there was a latent image (fancy term for invisible picture) on the paper which was only revealed once placed into the developer. This is because the silver bromide particles which had been hit by the light would react with the developer to produce solid silver, thus darkening the image. The more light that hits the spot, the darker the paper will turn out.
If we left the photograph in the developer though, eventually we would end up with a black bit of paper so we only need the photograph there for a minute before dropping it into our stop bath. The developer is an alkali, so the acidic stop bath does exactly what it suggests, stops the developer reaction from continuing by neutralising the reaction. The fixer solution strips away any extra silver bromide particles which remain so that when the photograph is exposed to the natural light outside the dark room it will remain unaffected i.e fixed (So they are not just clever names for each of the chemicals!)
It was a simple process that barely lasted 10 minutes, but it is not my pride in the fact that we produced nearly 4500 of these photographs during the festival that has led me to write the above. The real reason was my interest in the history of photography, as the entire process I’ve described above has been in use for well over 150 years. Below is the first ever photograph, taken in 1826.
Obviously it has become rarer in recent times, with digital technology and printing coming to the forefront of photography. It may not be a surprise to you, but we are very lucky to live in an age where to take a photograph all we need to do is push a button for a split second. During the festival even the parents sometimes struggled to keep still for 30 seconds, let alone the kids! So it may shock you to learn that in all those old Victorian photographs it was not uncommon for the subject to be still for hours at a time. Sometime they would have to resort to discretely clamping parts of their bodies so that they would remain still, but so that the clamps would not appear in the photographs themselves.
You may be wondering how they managed to get children to remain still for that amount of time also. Well, the Victorians solution was to camouflage the child’s mother in the background of the photograph to keep the child still. Well when I say camouflage, I mean they threw a blanket over them! There was another more morbid way of photographing children though, in which the photograph would be taken once the child had passed away. You can imagine the mother at her child’s bedside thinking, ‘well at least I can get a good photo of him!’
Even though the Victorians were naturally very reserved, the long exposure time forced them to smile even less, as you can imagine holding a smile for more than a minute would be impossible.
And since this has been about old style photography I will share with you my favourite one, the Gallant Pioneers of Rangers Football Club……