Photographie DIY : du chlorure dargent et des problèmes... | À vous la science #6

Hello! What I have in my hand, it doesn’t look like, but it’s a camera. A DIY camera, of course. You got it, today I’m gonna talk about photography, and even better: film photography. Before trying it on these beautiful flowers, which you can see behind me, let’s go to the lab, for some explanations and experiences. It is often said that photography was invented by Nicéphore Niépce. He was born in Chalon-sur-Saône, in Burgundy, and he took this picture in 1827, which is often mentioned as the very first photograph.

00:37 - Sure, he was the first to be able to make lasting photographs, but he was not the only one to have contributed to photography improvement. For example, on exposure times: the one of the previous picture is about several days. Not very convenient! Another man worked with mister Niépce: Louis Daguerre. The two inventors developed together the daguerreotype. This process gives pictures on silver plates, but only single pictures. However, exposure time is already decreased to about thirty minutes. Such a progress! Meanwhile in England, William Henry Fox Talbot invented photography on silver halide glass plates. It was in 1835, and this process solves a big disadventage of daguerreotype: It is possible to make several pictures with one negative! Later in 1884, flexible film is invented by George Eastman, founder of Kodak. Modern film photography was born. So much for the beginnings of analog photography, and now we roll up our sleeves, because we have some work to do! Film photography is called “silveric photography” in French, because films are made with silver halide. Many of them are light sensitive, like silver bromide, silver iodide and silver chloride. And I’ve chosen this last one.

01:59 - To produce silver chloride, I’m going to mix hydrochloric acid with silver nitrate, which I bought on the internet. But these chemicals are corrosive, so it is important to be protected by gloves, glasses and closed chemistry blouse - very important. They’ve forgotten antifog on my glasses, I do with it. I still see roughly. Well. I’m sure to remember you good memories of chemistry class with the chemical equation. And now, let’s go. Look at that. Voila! It’s magic! We’re seeing a precipitation of white material.

02:36 - It’s silver chloride! I have my light sensitive material. And I can’t see anymore, because my glasses are completely fogged up. It doesn’t matter. Well, what I have to record now? Sh*t! Wait wait wait, I have to cover it! It will turn… Wait, it should have already turned black? What the hell? I don’t understand… It should be all black! It is exposed to light… That’s it! I got it! It works only with daylight! Look at this! A little search on the internet never hurts, and it can be helpful.

03:18 - Silver chloride is sensitive to ultraviolet, and not visible light! And by the way, I’ve got my counterfeit detector out again, that works, I remind you, with UVA. So look at this, silver chloride turns gray. Actually, this is not this chemical that is used in films, but rather silver bromide. It is more sensitive to light than silver chloride, especially to visible light. However, it’s a little more difficult do make, and bromine is toxic too. This is the reasons that make me prefer silver chloride. So, silver chloride is made. Then I need a film, and I choose for that these glass plates, that are normally used for samples to observe under a microscope. To spread silver chloride out, I’m going to mix it with gelatin. It will be easier to do, and more durable. By the way, it was the process used in first photographic plates.

04:09 - Only downside: my plates won’t be vegan compatible, sorry… The image ratio I choose is the well-known 24 by 36 millimeters. That’s good: my plates are only two millimeters too long. Two tape pieces from either side, to have well-made borders, and to make a thin gelatin layer, and it’s all right! To do some tests, I need a camera. So, if I’m still recording, it’s because I haven’t sacrified mine yet. I made this one, which is very basic, but that ought to do it. It is a simple camera obscura, with on one side an opening and a PVC pipe, with at the end a lens - it’s a plain magnifying glass - and on the other side a window, where I put my plate. PVC pipe can slide, I can focus with that. Of course, because of the lockdown, tool shops are closed, and, even if it’s possible to be delivered, only first necessity items are available. So, I made my camera with what came to hand. This is why it looks ragtag.

05:06 - And I haven’t had paint anymore, to give to it a decent look. But it doesn’t matter. The most important thing is that it works! The operation is not very simple, because camera is basic. I explain to you. First, I put a plate with a sheet of paper, that helps me to focus thanks to the image showed on it. Then I cover the camera with a blanket. This blanket is useful to protect the plate against light, while I’m putting it. Last I discover only the lens, to take my picture, and when it’s finished, I cover it again. And I repeat the steps back.

05:39 - Because of long exposure times, I added to my camera a fixation on the bottom, to put it on the GoPro tripod. I have three plates. So I’m going to take three pictures, with three different exposure times. First, two minutes, then ten minutes, and last twenty minutes. The plate is in place. Ready… Go! Let’s go! timer noise Wait… Five… Four… Three… Two… One… Poof! Finished. It’s in the box, and it is appropriate to say.

06:20 - I put the plates in a steel box, which I rolled in the blanket, to be sure there won’t be any smallest rays of light! I don’t have any extra plates left, so it must work! Like you, I can’t wait to see the pictures! We go back to the lab to see the result! But before processing the plates, I have to explain to you how it works… I remind you, the chemical used in film photography is silver bromide. When it is exposed to light, it turns into metallic silver, but in very small amount. The picture on the film is unvisible for the moment. The first step of the process is the developer bath. Thanks to a liquid called “developer” that contains hydroquinone, each little crystal hit by light changes totally itself in metallic silver. In fact, developer bath amplifies the light action. Picture is revealed. The next step is the fixer bath, that removes remaining silver bromide. This is important to prevent it from darkening afterwards. A sodium thiosulfate solution is used. It reacts with it, and produces a chemical substance soluble in water.

07:24 - Last step is washing, and it’s done! However, I’m not going to do the first step with my homemade plates. I think the impact of UV light on silver chloride is enough to produce directly a visible picture. I just have to increase exposure time a little bit, maybe. However, the second step remains essential. And it is the same as with silver bromide: a sodium thiosulfate solution. Eh… Oh Yes, it’s right. So. I suspected that. Well, look at that. It’s interesting. I’ve got dark and light spots, but the big problem I’ve… Oops! Sorry. Anyway. So… I noticed that when I took the pictures: aluminium foil has stuck on the plates. And I think it has even reacted with silver chloride. It was time to process them! Well, let’s go. First: the two minutes plate. This one… Uh, it’s dark. I think… Oops! Look at this… Aluminium foil has really stuck on this one. And then, the last one… Great. I think this one is the ten minutes plate. Right.

We have: the two minutes, the ten minutes and the twenty minutes. Now, I’m gonna let chemicals to react between them. It may take several minutes. So meanwhile… I can sing to you a song… No, bad idea! Em… I can encourage you to support me on Tipeee. Yes, it’s important, to help me to continue these videos. And even a small contribution makes me happy! And if you cannot support me on Tipeee, you can still share this video. It’s very helpful, and it’s free! Well… I’m gonna drink a coffee, I think. Yeah. Pending it’s finished.

09:27 - So, we’re not going to lie, the result is a bit disappointing… I was expecting something better than that. First, aluminium foil really bothered me, as you can see. And Gelatin isn’t really transparent, I find. It’s rather translucent than transparent, and surface is rough. So, I digitized the plates, to see it better. And I’m going to work on these before processing. It’s the same. The process is useful only to avoid possible darkening. We can see some dark and light spots, that match to some details on the picture. I took me a while to find out which one. But look, for example: these light spots are the flowers that we can see here; this dark spot is this dark area in foliage; and this big light area, defined by leaves, is building in background, that reflects UV light. What can we say, to sum up? Well, the big problem with silver chloride is its lack of sensitivity to visible light. And I learned that by doing this video. Look at this spectrum. Its maximum sensitivity is at 365 nanometers.

10:28 - And beyond 425 nanometers (blue or violet), it isn’t sensitive at all. While silver bromide is light sensitive until 500 nanometers, with a maximum at 405 nanometers. How to make films sensitive to long wavelengths, for example red? Others chemicals are added to silver bromide. By the way, this is the reason why light red is used in black and white processing labs: Because silver bromide is unsensitive to it, it’s possible to enlighten with this kind of light. Of course, it’s a bit more complicated with color films…

11:01 - Even if this experiment wasn’t really successful, or in any case, not as I expected, I hope you enjoyed this video and you learned a lot of things. I would like to try again in the next months with silver bromide. I’m crazy! Waiting for it, you can follow me on Twitter and Facebook, it’s funny. See you soon with new projects! .