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Tuesday, December 10, 2013

Artistic color pictures manipulations

The last two months I have been shooting mainly digital. Admittedly digital photography is much easier and failures are less probable than with film. The digital pictures I took were very impressiv, thought they were made with a compact camera I bought recently, a Sony DSC HX-300 with 20 MP and a Carl Zeiss lens capable of 50 times zoom. Fantastic but I still miss the film photography, which enables much more challenge, both by shooting and processing.

I decided to test a FED 5-B camera with a Industar-22 lens. I charged the camera with an Agfa Plus 100 and went through the villages around my town. It was a clear Autumn day, camera speed at 125 and aperture around f / 8 for most of the captures.

The film was developed with Dignan's two bath method, using as bleach Iodopovidone (Betadine) and fixer of Ammonium Thiosulfate. The scanner was my Epson V500 and finally I treated the scans with the free software Photoscape, that allows you, among other possibilities, to transform your pictures in nice watercolors.

Monday, October 21, 2013

The problem of white spots in caffenol

It is a well known problem when using caffenol, any of the recipes of caffenol.
If you are using a coffee based developer, you might have had this problem too, on your B&W pictures. It may depend on the film used, but with Ilford HP5 for instance it is a very annoying thing, look to the following picture, scanned at 1200 dpi:

You can make the picture more presentable via software. I used the GIMP filter 'despeckle' and I've got the following:

It is said that if the film is very well washed after the developer, the spots will be tolerable, but I washed very well after the developer and it was still untolerable.

On my modest opinion, coffee developers are not compatible with the Ammonium Thiosulfate fixer. If coffee is a must for you, as it is for me, then better use another fixer. Sodium Thiosulfate is the best alternative, or even Ammonia. Sodium Thiosulfate may be prepared by boiling a solution of Sodium Sulfite with Sulphur.

The next I will be using Sodium Thiosulfate that takes longer to fix but, I hope, will give clean negatives. The spots look like silver grains and I make no idea why they precipitate on the film developed with coffee. The same fixer was used with Parodinal and no spots were produced.

Saturday, September 14, 2013

Would you stop shooting if no B&W films exist anymore?

I really don't know what is this useful for, but it is possible and I discovered it accidentally, to develop a C-41 film looking like a B&W film. No discernable color in it, a monochromatic image.

To achieve this result I started using my developer CSS, that contains CD4, to develop C-41. Using the accelerator for B&W film it produced a very weak image, so I decided to use the same accelerator as for paper but the same amount of stock solution at room temperature. Yes, it worked, I fixed the film and bleach, the image I obtained was monochromatic and could be scanned as B&W film giving acceptable B&W pictures.

The next step, and in order to turn this a process that can be reproduced by anyone, without special stuffs, I replaced CD4 by Hair Dye and it worked the same way, the amount of hair dye is maybe more difficult to precise, but I measured some 10ml of that stuff to replace 6 g CD4. Yo this new developer I called CSS-HD, where HD means Hair Dye.

After developing with CSS-HD you may fix normally with rapid fixer and then place the film in a bath of Iodopovidone, sold in the pharmacies as Betadyne in bottles of 500 ml. When it is new it acts very fast, maybe 5 minutes to dissolve the silver, but if used it will take longer and longer, mine needs now some 30 minutes. But no problem, it will not wash out the image, which I suppose is made of dyes but looking B&W.

Pure B&W and C-41 negative

Pure B&W and C-41 negative developed with CSS-HD

Picture from athe bove negative scanned as color negative

Picture of the first image scanned as color negative

Picture of the second image scanned as B&W

Saturday, August 31, 2013

I have got visits

An old friend of mine and his wife visited me this week and I showed them the place where I live and we took a small tour around. As first we visited one of the oldest paper factories of Europe, the factory is still working but only for demonstration to the visitors. It suffered a restauration under the advise of one of the most known portuguese architects, Siza Vieira.

After the short visit to the factory we walked to the antique center of Leiria and we entered its Cathedral. We were also in some other important places of the town like the Square Rodrigues Lobo and Park Camões and crossed the old narrow streets of the city.

After this short visit of Leiria town, we took a tour by car until the beach village of S. Pedro de Moel where we had lunch, looking to the Atlantic, «it was like we were on vacation». After lunch we went to the village of Nazaré, following south the «Atlantic Street». My friend told me he never uses GPS, we had a look to a paper map and we knew how to drive. I said to him that I prefer OWA instead of GPS. He asked me what OWA means and I answered: «Open the Window and Ask». All we laughed and were happy beeing together.

Old Paper Factory, built in 1411 in Leiria, Portugal

Dagmar and Hans
New pedestrian bridge over river Lis

Leiria Cathedral
During lunch at S. Pedro de Moel

At Nazaré, looking down to the village and beach

Once at home I developed the film and scanned to the computer.

My procedure is following:

Final Wash

As developer I am using Dignan NCF-41 -- Two-Bath C-41 Color Developer for a while, what means, for some months, with some slight modifications. As first bath I prepared following, because I could not find Sodium Bisulfite:

300 ml water
5,5 g CD4
5 g Sodium Sulfite
Water to make 500 ml

For the second bath I have allways a 5 liter jerrycan with a 5% solution of Sodium Carbonate and 0,05% Potassium Bromide, which means:

50 g/liter Sodium Carbonate
0,5 g/liter Potassium Bromide

In the Donald Qualls page it is recommended to use distilled water for the first bath and distilled or filtered water for the second bath.

About times, I use 10 minutes for the first bath, agitating continously during the first 2 minutes and then let stand. The second bath I stir for 5 minutes and let stand for more 15 minutes.

Between developer and fixer I wash very well for 5 minutes.

As fixer I use common commercial fixer from Foma, times and dilutions as prescribed. But because the fixer is not new and also there is no danger to overfix, I usually give 5 minutes fixing time.

As bleach bath I am using Iodopovidone, normally known as Betadyne that is sold at Pharmacies as disinfectant for wounds. Here you may control at light the degree of transparency you want, the film is already fixed and now the bleach will only remove the silver and the orange mask.

Finally I wash very well for at list one hour ant hang to dry.

Saturday, August 10, 2013

My new Flintstone camera

This is my 5th selfmade camera, but all of them were different. The first 2 were 35mm Pinhole small cameras, I could sell one at ebay and the other I offered my smaller daugther who was very happy with it. The third one was a bellows camera with a binocular lens, without shutter or with hand shutter to expose paper. Later I adapted a guilhotine shutter made by my self but giving shaking images because it worked with rubbers horizontally. The camera is still here somewhere waiting for beeing repaired or used somehow.

In the 4th camera I used a Rollei back for 120 film and a Leica Leitz Elmar lens and a guillhotin shutter by gravity giving good images, only the Rollei back sticks a little, it needs some more tuning work. The camera is there more like a museum piece on a table in the corner. Works fine, only to return the guilhotine in the upper position you must close the lens and invert the whole camera and reset the trigger cable that when released, let the guilhotine fall. No shaking images at all, great shutter.

Now, my 5th camera started with a wooden box of the dimensions 12.7 x 8.8 x 8.1 cm with hinges and latch. I used a Vario shutter (which advantage is to have everything including flash synchronyzer). This shutter had no lens in it but looking in the box where I put all optic devices left over from other projects, I found a 100 mm lens that with some tuning in the distance to the film could serve. This is more or less easier to do if we use a lens board and regulate the distance by adding stuff between the box and the lens board. I choosed the size of the lens board so that I can use it in a professional Horseman 980 too.

The trickiest part is the back cover of the box that works perfectly to load a 120 film and take, not 6x6, but 5x5 pictures, due to the thickness of the used wood parts, mainly the frame which slides and is held in position by two small parts of nails on both sides. Well, for the rest just look the pictures, they are clear. I use in the first steps a kind of spring to prevent the roll to unwind during the loading process.

The Flintstone camera

Inside the Flintstone camera

Loading film in the Flintstone camera, step

Loading film in the Flintstone camera, 2.nd step

Loading film in the Flintstone camera, 3.rd step

Loading film in the Flintstone camera, 4th step

Film loaded in the Flintstone camera.

Monday, July 15, 2013

Caffernal, first working recipe

I may now announce the first working Caffernal and its recipe is following, but please understand what I mean. To start, let us consider the balanced equation of the reaction between Ascorbic Acid and Sodium Hydroxide to give Sodium Ascorbate and Water:

C6H8O6 + NaOH → C6H7O6Na + H2O
176 g  + 39 g = 197 g + 18 g

The complete reaction needs 4.5 times (176/39) Ascorbic Acid in relation to Sodium Hydroxide.

But we don't want the complete reaction because there is a risk of surplus of Sodium Hydroxide that will give a high pH, or a risk of low pH that combined with coffee can go acidic and no development will take place. After some disasters, my starting point was fixed at 3 parts of Ascorbic Acid in weight for 1 part of Sodium Hydroxide and I end with a basic pH of 11,6, but still to high for ascorbate developer. So, I added coffee as acid to lower th pH to 10.6. And here is the whole procedure:

Preboil 1 liter water for 10 minutes and let cool. Add 5 g Potasssium Metabissulfite as Oxygene scavenger. Then use just 100 ml of this water in a beaker and dissolve 60 g Ascorbic Acid in it. Then put the beaker in a bowl with cold water and add 20 g Sodium Hydroxide and stir (don't forget gloves and googles). Pour some more of the cold preboiled water, say, 50 ml. The color of the mixture is light yellow. At the end of the solution measure the pH which will be about 11,6. Now weight about 60 g soluble coffee and go on adding to the soup and measure the pH. When you reach 10,6, more or less, stop. Add 5 g Potassium Bromide as anti-fog (it is enough). Add some more of the preboiled water to make 250 ml and store in an amber bottle of 250 ml. You have prepared the stock solution of Caffernal.

According to my experiments, for each 100 mg Sodium Hydroxide more than the necessary, you will have to put more 1 g of coffee. Suppose that by mistake you putted 2 grams more of Sodium Hydroxide, this will need 20 g coffe to neutralize it. So, be careful and don't waste resources, unless you want to change the proportion Ascorbic Acid to Coffee for a developer with other properties, more grain, more contrast and so on.

And so we have constructed a developer that can be used very diluted. I have been using it in dilution 1:50 and I need some 60 minutes at 25ºC to develop well the film Ilford FP4.

Have fun with Caffernal!

Note: For better understanding, I add a small explanation in red.

2.nd Note: Sodium Ascorbate has a pH between 7.4 and 7.7. Without a surplus of alkali it will not develop.

Tests with Caffernal

3.rd series of Caffernal developed photos

The photo above was taken with a Adox Golf 63 at 1/200 and f/8 with Ilford FP4. No software enhancement was applied, just as it came from automatic luminosity of the scanner.

Caffernal looks like a fine grain developer, low contrast and good restitution of the whole grey scale.

In the dilution 1:50 it takes a minimum of 60 minutes to develop at 25ºC.

Now, comparing this developer with the Caffenol C+, using Sodium Hydroxide as alkali too, I found a way to change the properties of Caffernal, I am about to test these possibilities.

The aim of the changes is to make Caffernal faster than it is now. In comparison with Rodinal it is some 4 times slower or more. The contrast can be also pushed a little, I think.

Saturday, July 13, 2013

Caffernal advances

Today, because it is too hot during the day, I left home about 8 o'clock in direction to sea, where I would like to make some pictures with my Holga 120 GN adapted to 30 photos 20x30 mm. The weather was very cloudy and I had to use the bigger aperture of the Holga and the sharpness of the photos are not ideal. Once at home, I developed in Caffernal dilution 1:50 for 50 minutes at 25ºC. Well, it needed some more minutes, maybe 60 minutes, which is consistent to my experience using caffenols with 1g/l coffee and Vit. C. OK, but the pictures could be sacanned without problem, dark areas have less details.

On the other hand, the highlights are superb, it was possible to see the small sky clouds shadows. I think in a not so cloudy day, the clouds would be fantastic.

Here are some choosen photos of the series:

The smal differences in sky density could be registered

Good grey scale

Testing depth of field, setting for group

Rock and sand

Rocks and water

More rocks, see difference sky/horizon

Head of the big chief

A couple photographing

The beach sight from above

Another sight of the beach

The typical portuguese coast to Atlantic 

Friday, July 12, 2013


After having succeeded with a Caffenol using Sodium Hydroxide as alkali, the Caffenol C+, I wrote an article about it at, I started a series of experiments to see the limits of how few I must use to develop. From many developers made with some logic I experimented, only perhaps the Caffenol 3335 (3 g Vit. C, 3 g Sodium Hydroxide, 3 g Coffee and 5 g Potassium Bromide per liter) is worth a try. But maybe you should raise the potassium bromide to 10g/l. Or, wait, you don't need so much, the proportions are not quite right as I discovered later.

But the new project I have is to find a based on coffee and vit. C developer that works similar to Parodinal. I started calling it Caffedinal but I worked so hard until I got reasonable results that I changed the name to Caffernal. I am still experimenting but I can already say it will be a reality. The photos below were made using a 1:25 solution and 20 minutes at 27ºC and I think it will work at 1:50 solution too, already tried but the duration was short (45 minutes), images too weak.

The final recipe is still not fixed but it is more or less obvious that coffee, vit. C, Sodium Hydroxide and a pinch of preservative and restrainer will also be included.

A corner in my flat
Picture 1 - Semi-stand development, not recommended, see the shadows of the perfuration

Kitchen darkroom
Picture 2 - 3 minutes constant agitation and the one minute every 5 minutes

Not chinese, all portuguese
Picture 3 - Same as Picture 2

Friday, July 5, 2013

Finally some color again!

The long term task of this blog is to publish a recipe for developing C41 films without CD4. Meanwhile I compromised and putted small portions of CD4 in my soups with coffee and yes, you may use coffee not as developer because it will only develop silver but seems to act as stabilizer, like Hydroxlamine Sulfate. The recipe I gave first, Caffcol I works and works satisfactory, it is a only different from normal c-41 developer because it has coffee instead of Hydroxilamine Sulfate. The paper of this stuff is to keep dye grains small, what maybe coffee does too.

In a thread at Flickr, I discovered this picture of Marschal A. Fazio (Pothman), that he made using Rodinal and hair dye in a reversal (?) process. He says:

"I used about 3-4ml of rodinal and 10ml of liquid hair dye from Loreal (it was a bottle of liquid color i got at the beauty supply store, it was a shade of black) that was mixed in 500ml of water. developed for 20 minutes at room temp. The bleach was left over from a C-41 kit (Rollei digibase). I used the same mix of hair dye from previous developing for the redevelop."

Since yesterday I am trying to reproduce the experiment, I have nothing really exciting yet to show you, but maybe some of theses days, who knows.

Report of what I have tryied until now:

I prepared the developer like suggested, 3-4 ml not of Rodinal but self prepared Parodinal for 500ml water and about 10ml hair dye, but not the same brand of Loreal. I was so convinced of the success that I went out and exposed a 36 Agfa 100 and developed with this developer. After the first development I filled the tank with a bleach bath of a Tetenal kit for some 4 minutes and oppened the tank to expose the film to light. I expected a blank film but no, it was developed in black and white, looked very nice as black and white pictures. I submitted then the roll to a stronger bleach, Potassium Dichriomate + Sulfuric acid and the result was to bleach out almost all, leaving the roll damaged. No, this way it doesn't go. I need another bleach bath...

I exposed then short pieces of film at home and tried again, the same developer but as bleach I used this time Betadyne which takes hours to act but goes safer. I bleached for some 3 hours and then exposed to light and redeveloped. I have got color pictures but very weak. This was yesterday!

Today I restarted exposing small pieces of film at home and develop them using Parodinal and hair dye. I read somewhere that Parodinal or Rodinal alone is a very weak color developer too. So, this time I took as first developer only a 1:50 solution of Parodinal for 10 minutes only, stiring constantly. Then I submited the film to 45 minutes Betadyne and the result was a almost B&W developed film, without the orange mask, the Betadyne removed the orange mask but leaving the silver untouched. I divide the experience in two parts, cutting a portion of the film to be fixed and washed like it was and the other portion I left in Betadyne for one hour more, controling the process until I see that the silver was bleached leaving a little a weak image of dye. Then I redeveloped in the same Parodinal with two spoons of the first prepared developer of hair dye. The image got more density althought the color restitution is not that good.

Example of the first part, bleach during 45 minutes with Betadyne

The same image warmed with software

Direct scan of the 2 hours bleach + redevelopment with Parodinal and a little hair dye only
From the same second part but enhanced with software
I wonder what could have happened if I used a little more hair dye in the second developer. 

Wednesday, July 3, 2013

Difraction rings of the Sun photographed with a Holga

By chance and not planed, photographing with a Holga 120 GN with a 6x4,5 mask, I centered the Sun at the edge of the upper side of the mask. My first thought was, «Oh, I have a light leak there. But looking closer I could see what happened. This was the first time I noticed such rings in the not directly exposed part of the film. The most curious is that the entire film was exposed at the B position, unwanted and is overexposed, the image is very white.

Sun development I
Newton rings of the Sun?

I did an enlargement of the rings as shown below:

Sun development II
Newton rings of the Sun?
Well, I thought that perahps many of you never saw this effect, like me now, so I decided to make a post on it.

This happened when I was exposing a film to be developed in the not so successful new Caffenol 5555, the film was also overdeveloped but this issue could be repaired by bleaching and refixing the film. The margins are now transparent and clean like they should be from the beginning. But the film was completely black after first development.

Whether this phenomenum is physical or chemical, I don't know. I would say it is physical and has to do with the difraction of the light passing a sharp edge.

Monday, July 1, 2013

The future, what will be, will be.

I do not understand that transparent film, acetate or polyester, is still the preference of many of us in what «physical and chemical» photography is concerned. A transparent support is not needed anymore... Yes, I know that many voices of film fundamentalists will rise and they will start pointing advantages that only film has and so on, but think practical: I heard that Kodak stopped manufacturing papers and films (correct?), the other classic brands will follow this tendency. It is already difficult to get 120 film at the street, only at internet. Cheap alternatives like Foma and Shangai with many imperfections will serve until... well until some new brand reintroduces PAPER FILM, panchromatic, to be developed like film in tanks but that is much practical to keep and to reproduce with reflective scanners. Can you imagine a roll of 120 thin paper with some 50 pictures for your Holga or Horseman? Yes, it will come some day, nobody really tought about but it would be a very good business. Negative or direct positive paper, but negative can easily be inverted by scanners or softwares.

The advantage of such a change is to preserve the procedures we now have for film and our hobbies discovering new developers and perhaps also toners. Well, I must say, I would be very glad if some brand discovers this «mine» idea and I am sure, they would pay me some royalty when they see the results.

The picture below was made using film, but some of these days I will prepare a roll paper film and try to make the same photo with paper.

Church center

Saturday, June 29, 2013

Caffenol Q (with Hydroquinone)

A brief search in internet, and I found nobody tallking about this combination of coffee and Hydroquinone, one of the standard developing agents used in many developers of several brands, Kodak, Agfa, Ilford and so on. Alone or combined with Metol, the more soft brother that lowers the contrasty pictures developed by Hydroquinone, which alone may be used only for paper or in lithography negatives where high contrast is desired.

Many people are convinced that coffee has a natural brother, this would be the Vit. C. The mix of coffee and Vit. C is indeed very good, it turns coffee in a decent developer, not so grainy and foggy.

Now, in a series of tests I undertook, I have found that Hidroquinone also is a good brother of coffee.

First of all, I prepared 10% solutions of coffee and hydroquine, the last one in a methanol solution. From each of them I prepared 250 ml bottles. Then I mixed 10% of the 10% sol. of hydroquinone with 90% of the 10% solution of coffee (in this solution I putted 0,5% sulfite for better conservation). I had then 50 ml of stock solution containing 1% of hydroquinone and 9% of coffee. To this stock solution I called Caffenol Q, Caffenol Hydroquinone.

Then I used a 5% solution of soda with 0,05% Potasssium Bromide as activator for the developer, using only 10ml/500ml to develop a Shangai 100 ISO film, during 1 hour at 20ºC, followed by normal wash and fixer baths.

Here is one of the photos:

Red sky
Old typical house

Final note: very good negatives, good contrast and highlights, very little grain. Only one problem, I don't know if I live enough to use all that stuff. Maybe you can help me, besides I need to test other mixtures, Phenidone for instance.

Saturday, June 22, 2013

Maths again!

As you know from reading before, I have been studying the general purpose developers with Metol and Hydroquinone, the so called MQ developers and I am now proposing a family of such developers, having several of them in account. I propose the following general expression to calculate a MQ developer, with a small deviation from what I proposed before:

Metol + hydroquinone = K g/liter
Sodium Carbonate = 50 - A x Metol g/l
Sodium Sulfite = 100 - B x Hydroquinone g/l
Potassium Bromide = 1 to 3 g/l 

Anyone may estimate the right values for K, A and B. I could also have choosen other maximums for carbonate and sulfite but 5% and 10% seem to be commonly accepted for baths where they appear alone. The other parameters, K, A and B I leave to individual choice. I am going to start with K=10, A =6,67 and B=10.

I assumed that the sum of developing agents is a constant, developer using only hydroquinone needs only sodium carbonate (50g/l) and developer using just metol only needs sodium sulfite (100g/l).

Let's make a developer respecting the expressions with my parameters for K, A and B.

I choose Metol = 3 g/l, so Hydroquinone will be 7g/l. Sodium Carbonate will be 50-6,67x3=30g/l and sodium sulfite will be 100-10x7=30g/l too.


Metol - 3 g/l
Hydroquinone - 7g/l 
Sodium Carbonate - 30g/l
Sodium Sulfite - 30 g/l
Potassium Bromide - 1 g/l

This developer may be called MQ371. 

Thursday, June 20, 2013

Developing photos with just soda

Do you believe this? But it works! Some will say that the papers already have a developing agent, but I did the same with a bromide paper prepared by me and it works the same way.

In my previous article, I told you about what I discovered with my own printing paper, I could develop weak images only with a red light and no need of a solution to make the image appear. I just leave it at sun with a red filter and the image comes up. It is rather difficult to fix this image, I have been washing very well the paper and then using normal ammonium thiosulfate. But the image becomes lighter and almost white in some cases.

Today my silver nitrate finished and I decided to use normal bromide paper, Ilford Multigrade IV brillant. Exposing the paper first to normal light and then to the red light, the latent image comes up too but still much weaker than with my own produced photo paper.

I thought, well, I have to purchase more silver nitrate and wait until it comes and go on with the experiments. But... I had an insight suddenly:

In fact, the red light acts like a developer agent. So, why not making a soda bath and develop the paper in just soda exposed to the red light just over the tray of soda?

And I started spoiling sheet after sheet, first exposing the sheet to the red light and when I saw a faint image, down to the soda bath but allways happened that the paper becomes black very quickly. And then I started reducing the exposure to normal light and things went better. At the end I was developing in one minute as normal and the image was OK. But I had to use a flash pointed to the ceiling to get the right amount of light, the fluorescent light was too much and difficult to regulate for just a second or so.

The paper was showing to be much more sensitive in this way as in normal process with developer. Then I thought, maybe I can expose a sheet of paper in the camera for 1/100 sec. and f/8. Yes, it worked but I had to lower the speed to 1/50 to get a darker image with f/8. So, the paper was showing a sensitivity of about 12,5 ISO, applying the f/16 rule. But that is normal for bromide papers when using latent image.

But the problem of fixing the image still exists, I am making now a stop bath of vinager and then I let the photo for a while in just concentrated salt. The image stays OK, but I still don't know for how long. If it is time enough to dry and be scanned, it may serve for something.

(I am waiting for the pictures to dry and I will post them here.)

The photo above is a contact print of an acetate printed with laser printer.

Developed with light and soda
The photo was taken with a Zeiss-Ikon 9x12 and lens Wollensack

Wednesday, June 19, 2013

How did Talbot take the negatives?

The first ancestor photographic process that I have tried was the daguerreotype. With some success, disregarding my bad method of coating copper plates with silver metal, which leaves, after some time, the entire surface divided in small fractions, although the image persists. I learned about the process, but if I wished to improve my photos, I would need to invest more time and money to get the right tools and materials, and not just 'scratching' as I did.

The second historical process that I am trying since a few days is the salt print, invented by Talbot to make the copies of the negatives. My first results have been very promising and easy to obtain. The process is particularly simple, you just need things easy to find as some tools and trays, it is in a very closed relation to modern paper photography. The main difference is that it doesn't take advantage of the latent image, it uses only the image formed gradually by the incident light, which converts the silver halide in silver. This may take a few minutes, the process is not therefore suitable for taking pictures with a camera in fractions of a second, or in a few seconds, like with the daguerreotypes.


The above picture is an example of salt print, with a small difference, instead of common salt, sodium chloride, I used the potassium bromide, which works the same way. After several minutes of exposure to light, the paper is well washed and then fixed in common fixer. In this very early stage of photography, Talbot used as fixer common table salt in a warm and concentrated bath.

When making salt or bromide prints like this, the printing paper is given a thin coating of salt or bromide by means of an aqueous solution and leave it to dry. Then a thin layer of silver nitrate is added with a brush or a glass rod and it will combine with the chloride or bromide, or halide, to give the silver halide, which is sensitive to light. After further drying, a transparent negative is placed in contact with the paper and exposed to light, bright sunlight is ok! The paper will become more and more brownish, and when you think it is enough, it is washed very well and fixed as I said before.

Photographic modern B&W films or papers are different, they are coated with a layer of an emulsion containing silver halide. They use the latent image and need, therefore to be developed with an alkaline bath, and then washed and fixed.

But how did Talbot managed to take the pictures in the camera? He also used the laten image in a very complex process called calotype or talbotype, see description here, for instance.

But I discovered, by almost pure chance, a simpler gelatin dry process which uses latent image and is developed like the daguerreotypes, using Becquerel's method of exposing the latent image to red light. Here is a picture made in that way.

Edgar Alan Poe

A lot of work must still be done to produce more dark and contrasty pictures, but the idea works. Meanwhile, I already made more positives using the latent image which is projected for 20-30 secs with fluorescent ligh on the sensitive surface and then developed during about one hour by exposition to red light.

My older grandson