Alan Marcus

The chief working ingredient in the developer is the developing agent. There are many different chemicals for this task however most are associated with benzene. The developing agent seeks out exposure salts of silver. This is a timed rection based on chemical strength and fluid temperature. During this few minute’s soak in the developer, those silver salts exposed during the camera exposure are reduced. Reduced in this context means, the exposed silver salt crystal is fractured into its two component parts. The silver part is liberated from the salt compound, it forms a tiny tuft of metallic silver. This silver fluff balls is opaque and thus appears black. The developing agent is naturally not selective. In other words, it will attract both exposed and unexposed silver. The developer solution formula contains a retardant which is bromine. This addition coaches the developing agent to operate mainly on exposed silver salts. The developing action is somewhat slow. To speedup this reaction, a chemical called an accelerator is added to the developer solution formula. The accelerator is an alkaline that sets the pH of the fluid, it is made basic (alkaline). Various accelerators are used. The stronger the base faster the developers will do its job. Should the pH become acid, developing is slowed or halted. The next step after the developer solution is the fix solution. This solution renders the film or photo paper permanent. It does this by dissolving silver salts that the developer has ignored. The fixer is a sodium or ammonium thiosulfate. This solution tends to liberate sulfur as it ages. Making this solution acid plus adding a preservative adds longevity. Now the developer is an alkaline solution, and the fixer is an acid solution. Should the two fluids intermix the resulting pH moves towards neutral which is 7. This mixing together of the developer and the fix forms carbon dioxide gas. It forms in the mixed solutions, and it forms inside the film creating gas bubbles that spoil the film. The countermeasure is to use a stop-bath solution between the developer step and the fix step. The stop bath is simply a mild acid. Mild to prevent gas generation. Also, since development takes place in an alkaline solution, the stop bath arrests all developing action. Further, since the life of the fix is prolonged by making it acetic, developer that otherwise would ride piggyback on film or paper is neutralized. Thus, using a stop bath is a win-win. It stops developing dead in its tracks and the acid in the stop bath carries over into the fix prolonging its life. We use acetic acid diluted with water for the stop bath. This is the stuff of table vinegar. Many dark-room workers use plain water as a stop bath. This works but not as fast plus the life of the fixer is not well-preserved using water. Should sulfur be liberated in the fixer solution, it attacks silver and tarnishes it. The tarnish is blown or sepia. Sometimes we like this look, so we treat photo papers in a mild sulfur solution. The result is a brown toned print. A second reason, the brown toned print is archrival. Silver sulfide is inert so the image likely will outlast the paper.

Modern photo films like Tri X consist of salts of silver imbedded in purified gelatin. The silver salts we use are silver bromine, silver chloride, and silver iodine. These compounds of silver are light sensitive. In other words, when light plays on these silver salt crystals, a chemical reaction occurs. Given sufficient light exposure, the two component parts of these crystals fracture. The silver portion forms a tiny fluff ball of silver, the other portion, called a halogen, revers to its elemental form. The tuft of metallic silver is opaque thus it looks black on backlighted film. The word halogen is Swedish for salt maker. Unexposed silver halogens resemble ordinary table salt however the crystals are off white (cream) and they are super tiny. Gelatin is the glue (binder) that holds the silver halogens onto the transparent plastic film base. In the camera, we only allow them to receive a teeny exposure to light. The light energy they receive is insufficient to cause a visible change. Nevertheless, a change has taken place and an image of the vista being photographed is formed. This is an invisible image we call this a latent image. After exposure in the camera, the film with its latent image is submerged in a developer solution. This solution is mainly water with 4 other ingredients. Water is the solvent that holds the developing agent. This is a reducing agent that is able to differentiate between exposed and unexposed silver halogens. When it encounters an exposed crystal, it fractures (reduces) it to its two component parts. Unexposed crystals will be fractured if the film is submerged in the developer solution for a super long time however we will pull the film out before this can happen. The developer solution contains an alkaline that sets the pH basic. This accelerates the developer’s ability to fracture exposed crystals. Additionally, there is a restrainer additive that retards crystal fracturing unless the crystal has been exposed. Lastly, there is a preservative that reduces the likelihood that the developing agent will take on oxygen. If it oxidizes it reverts to coal-tar and loses its ability to develop plus the coal-tar will stain the film. The alkaline accelerator also causes the gelatin binder to swell like a dry sponge plunged into water. This action opens ups the pours of the gelatin allowing the developer solution and other following solutions to enter the structure, percolate about and then exit with agitation. Now chemical activity is also accelerated by higher temperatures. Most developers are formulated to work at 20⁰C = 68⁰F. This is considered room temperature by chemists. Higher temperatures cause the gelatin binder to swell more thus the gelatin will be more porous and this hastens fluid flow inside the emulsion (what we call the gelatin silver halide coat). A colder developer takes longer to do its work. One last point -- film is multi layered. A over-coat to protect the emulsion, one or more emulsion coats with different light sensitivities, a primer coat to hold the emulsion to the film, a back coat called antihalation coat. All expand and contract with temperature at different rates. If the developer solution is too hot or too cold, the tempo of the developing action changes. Additionally, the finished film will likely take on an unwanted curl. If the developer solution temperature is extremely different from the other fluids of the process (incudes wash water), there is the possibility the gelatin with shatter and look like a splintered glass window (reticulation). Best we keep all the fluid temperatures nearly the same. All the fluids of the process will work OK within a moderate range. Developer immersion times change with temperature. The developer instructions publish revised developing times based on temperature and dilution strength. We consult these published tables for revised developer time for temperature, dilution, and number of rolls previously treated.

The light-sensitive coat called an emulsion consists of salts of silver imbedded in purified gelatin. The structure of the gelatin binder, under the microscope, resembles spaghetti strands. This noodle-like structure swells as the waters of the developer are absorbed. Wet gelatin has open pores; this allows the fluids of the process to enter, percolate about, and exit with agitation. As the process proceeds, we wash the film and/or use a rinse agent to rid the emulsion of the chemicals of the process. Last, we use a wetting agent that reduces the likelihood of the rinse water from beading up leaving fluid standing on the gelatin’s surface. Next, we air-dry the film. As the film dries, the gelatin binder shrinks back to its original thickness. Should the final wetting agent (PhotoFlow or equivalent) be omitted, we must squeegee the film to remove beaded or standing water. Should beading of standing water remain on the surface, it interferes with the gelatin shrinking process. The result is a higher surround area that looks like a stain, called a water mark. Water marks are hard to remove. Gelatin swells in an alkaline solution. Try soaking the film in the developer. It is an alkaline solution, and this process will soften the gelatin. Don’t worry, fixed film will not re-develop, so no harm except the film is soft and easy to scratch. Soak for 5 minutes and then wash in running water for 10 minutes. Soak for 30 seconds in a rinse agent and hang up and allow to air dry. Maybe a 25% chance of improvement. An old trick -- If you print on photo paper using an enlarger, some have a negative carrier that allows printing wet negatives. If this is the case, print wet using the enlarger, likely the water mark will not be seen.

The photographic image can be ruined by a phenomenon called halation. Specular highlights (bright refection from metal or glass or polished surfaces) play on the film’s surface during exposure. These super bright light rays will penetrate all the way through the light sensitive emulsion, hit the back pressure plate of the camera where they will be reflected into the film from the rear. The result is a halo like ring of exposure spreading out from the highlights. Well studied by Professor Hermann Vogel, Berlin Technical, who in 1873 added dye to film to absorb this unwanted light. The color of the dye is the color the film is least sensitive too. This addition is called an antihalation coat. Vogel tried many ways to remedy. Once he dyed the entire emulsion yellow. This worked but to his surprise, the emulsion formula gained sensitivity to green light. Heretofore it only responded to blue light. His improved emulsion yielded black & white emulsions that imaged with greater accuracy. His improved emulsions were called orthochromatic. His graduate students made further gains by adding different mixes of what is called sensitizing dyes. This resulted in panchromatic films, sensitive to blue, green, and red light. The developer solution which is mainly water, is a solvent for the annihilation and the sensitizing dyes. Thus, the fluid changes colors as films are being developed. These color changes are harmless. Note: The developing agents used in modern film developers are related to benzene. Benzene was initially obtained from coal tar. The various developing agents have an affinity for oxygen. Thus, they take on oxygen that is dissolved in the waters of the developer. The oxidized developing agents revert to coal tar. Working developers are usually straw colored, they change to black and become opaque as they work and age. Developers contain a preservative that retards aerial oxidation and neutralizes its staining ability.

In 1727 T. H. Schulze discovered that a compound called silver chloride darkened when exposed to light. He had discovered one of the most important chemicals used in modern film-based photography. Images of stencils and shadowgrams were now possible, however the images faded quickly. In 1837 J.B. Reade discovered that a chemical called “hypo” mixed with water rendered silver-based images permanent (fixed). The light sensitive coat (emulsion) used on modern films consists of silver crystals called silver salts imbedded in purified gelatin and coated on a plastic base. When loaded in a camera and exposed to an image of a vista cast by a lens, the silver salts undergo a change. The change is too subtle to be noticed. Nevertheless, an image of the vista, be it invisible, exists. We call this a latent image. We bathe the exposed film in a solution called a developer. The developer is mainly water, however it contains an agent that seeks out those silver salts that have been exposed to light. The developer fractures these exposed crystals into their two component parts (silver and a halogen). Halogen is Swedish for salt maker. The halogens we use are bromine, chlorine, and iodine. The job of the developer is to reduce those silver salts that have be exposed and ignore those that have not been exposed. When reduced, the silver component of the crystal remains imbedded in the gelatin binder of the film, and the halogen component dissolves in the waters of the developer. The imbedded silver is a metallic tuft that is opaque -- thus metallic silver forms the image. The image that results is beautiful, but the tufts of metallic silver are surrounded by salts of silver that were never exposed, and thus remain undeveloped. These unexposed crystals will in time, self-reduce, liberating metallic silver that appears dark (black). In other words, the beautiful image will fade to black in an hour or so. The countermeasure to the self-fading is a hypo solution. This solution is selective. It targets unexposed, thus undeveloped, silver salt crystals. This is the fixer that renders films and papers permanent. In just 10 minutes hypo dissolves away all the unexposed salts of silver. While the hypo will attack metallic silver, this action is not quick; the film or paper will be removed from the fixer long before any detrimental action occurs. In summation: The developer is selective in that it works on exposed silver salts ignoring the unexposed. The fixer works on unexposed silver salts ignoring the metallic silver image. The traditional fixer is Sodium Thiosulfate. This works fast but during World War II Ammonium Thiosulfate was discovered. This fluid works twice as fast and thus it it’s called rapid fix.

Modern photo films consist of a transparent film base topped with what we call an emulsion. The emulsion coat is highly purified gelatin. Gelatin under the microscope resembles a tangle of spaghetti-like long chain molecules. The light sensitive compounds, silver bromine, silver chlorine, and silver iodine, consist as tiny crystals imprisoned by the spaghetti-like tangle. The gelatin binder is chosen because it is transparent, flexible, plus not very soluble in water. However, gelatin soaks up the waters of the developer (mainly water) and this causes the gelatin binder to swell much like a dry sponge plunged into the bathtub. The now swelled gelatin allows the solutions of the photo developing process to infuse and percolate about. This is important because fresh developer enters the structure and is quickly exhausted in areas where exposure is high. Because the wet film has a swollen binder, agitation supports the entry and exit of the fluids of the process. In the camera, the silver salts have received an exposure to light (the latent image). This light energy was insufficient to cause the latent image to be visible. The developer is a reducing agent that seeks out those silver salt crystals that have been exposed to light. The developer is selective; it reduces only the exposed crystals, fracturing them into their two component parts. The silver part is thus separated and become a tuft of metallic silver which is opaque -- thus it appears black. The other part, called a halogen (Swedish for salt maker) dissolves away in the waters of the developer. Again, unexposed silver salts remain unscathed. The image you see in black & white film and prints is made up of countless tufts of metallic silver. Color film works much the same except additional steps will imbed dye adjacent to the tufts of silver. In the back & white process, we now remove the unexposed and thus undeveloped silver salts. This is the job of the fixer (to render permanent). In the color process, the silver image is chemically changed back to a sliver salt using a solution called a bleach, which leaves the dyes intact. Follow the bleach with a fixer and the color film consist of dyes imbedded in gelatin. To answer your question more completely: The swelling of the gelatin to allow the fluids in and out is a timed reaction based on the temperature of the fluid. Also, chemical reactions are accelerated by a warm environment. A remarkable fact about gelatin: it shrinks back to normal size as the film dries (like a sponge).

They contained mixes of glycerin and glycol (the stuff of anti-freeze).

Soak in water, add an ounce of glycerin (from drug store). Air dry under a towel. Place a heavy flat object atop as they dry. When dry, they will be much flatter. They curl because the image is silver imbedded in gelatin, and it has shrunk while the wood pulp paper base has not. Glycerin will add some moisturizer to the gelatin, and this will help.

The only thing I can think of --- Medium format film size 220 is the same width as 620/120 film but it is double length 1440mm (56.7 inches), twice the number of frames. Unlike 120, there is no backing paper behind the film itself, just a leader and a trailer. This allows a longer film on the same spool, but as a result there are no printed frame numbers for old cameras that have red window as frame indicator. (Moreover, light from the window would fog the film.) Also, since the film alone is thinner than a film with a backing paper.

These are called Lantern Slides. These were popular - On glass black and white photo emulsion exposed in camera or exposed from negative onto silver salt emulsion via an enlarger. Look up Lantern Slide.

The amount of exposing energy is given in logarithmic notation, otherwise, the graph paper length becomes inconvenient as to length. Most graphs plot in ½ stop increments. The test exposure strip likely covers 21 steps. To plot on graph paper using decimal notation requires a sheet of graph paper many yards long. Even if the plot only covers 14 exposures, that’s 8,192 times the 1st exposure. Using log notation base 10, 0 represents 1: 1 represents 10: 2 represents 100: 3 represents 1,000: 4 represents 10,000. Thus, using log notation makes the graph more easily interpreted. As to slope: Use a protractor and find the angle of the slope. Typical pictorial film has a angle of about 38⁰. Next, we find the tan of this angle = 0.8. This reveals the contrast. If the angle is 45⁰ the tan = 1. Now the f-stop is a 2X change in light energy. The value 2 in log notation base 10 is 10 elevated to the 0.30 power. For convenience we just say 1 f-stop = 30 units of density change. However. that is true if the slope angle is 45⁰ (gamma 1). That is likely too contrasity, so films typically have a slope of about 38⁰ gamma 0.8. For this contrast, 1 f-stop change is 0.3 X .8 = 0.24 density units change per f-stop. Nobody said this stuff is easy. Also, for color negative film, it was designed to produce prints on paper using an enlarger. The enlarger is equipped with cyan, magenta, and yellow filters plus lens aperture and time of exposure. All are used to control the exposure film to paper. Because the cyan filter is a poor red controller (crosstalk), its use is avoided. Thus, the system is biased so the cyan filter is seldom deployed. That dictates that the red exposing energy be controlled not by the cyan filter but by exposure time and or lens aperture. To achieve this, the lens aperture is stopped down to obtain the correct red exposure. The green and blue light on the easel are now in excess. Magenta filters are deployed to adjust down the green exposure and yellow filters to control the blue exposure. This is the reason that, for a color negative film, the red emulsion is the one measured for ISO (speed).

If you want to make the Bleach -- Ammonium Ferric EDTA solution (50 - 60%) 200 ml Ammonium Bromide 150 g Disodium EDTA 10 g Ammonium Sulfite 10 g Dissolve in 500 ml water Using acetic acid -- adjust the pH to 6.5 How it works -- The developer reduces exposed silver salts (silver + halogen which is bromine or iodine or chlorine). The reduced halogen goes into solution (waters of the developer). Opaque silver makes up the black & white image. The bleach attacks the silver returning it to silver + bromine. The fixer follows and dissolves away the silver salt. Now the dyes show in all their glory. Halogen is Swedish for salt maker. In photo we use only three halogens Iodine lowest ISO films -- Chlorine next highest ISO -- Bromine highest ISO. Films and papers can be blends of different Halogens.

The name "bleach" is a misnomer - the C-41, RA4, and E-6 bleach chief ingredient is EDTA (Ethylenediaminetetraacetic acid. It is a chelating agent, and not a bleach as you know bleaches to be. Modern color films and color photo papers are black & white emulsions. Laced in is incomplete dye. These are Cyan - Magenta - Yellow dye in an incomplete state called Leuco (Greek for white or colorless). The miracle of these materials is all three dyes are missing just one common ingredient present in the color developer. The color developer is black & white developer plus it contains the missing ingredient. As the developer works, it forms metallic silver brining up a black and white image. As the metallic silver forms oxygen dissolved in the waters of the developer tarnish the silver as it emerges. This is the catalyst that unites the missing ingredient, now the dyes blossom and a color picture is superimposed with the black & white image. The black & white image veils the color images. The bleach solution attacks the silver and chemically changes it to a salt of silver. Siver salts are solvable in fixer and are dissolved away. Now the color images become vivid. EDTA is used in foods and medicines. It won't stain your sink. Some people are allergic and thus in danger of getting a skin rash. EDTA is used to rid the human body of heavy metal poisons - it is a valuable medicine. Photo color processes once used potassium ferricyanide as the bleaching agent. It works better than EDTA but the name spells trouble even though it is not toxic. EDTA replaced years ago. The combined bleach - fix is inferior to separated bleach bath followed by a fix bath. However, use of the combined blix is a common practice for convenance..

Film and prints and slides sent to a photofinisher are not the property of the lab. The lab is preforming a service like a laundry. If the lab mishandles someone’s picture, then likely a lawsuit follows. Once a route driver took a picture envelope and showed nude pictures at a bar. The employee was fired, the lab was found guilty of negligence, big bucks were awarded. This kind of action is serious stuff.

Outline of steps / times / temperatures K-14 1. Removable Jet Black Backing (Rem-Jet) Removal 10 seconds ambient temp subsequently buff-off 2. Rinse 15 seconds @ 85° -2 +15 3. First Developer MQ formula 2 minutes 0 seconds 99°F ± 0.05 4. Wash 45 seconds 85° ± 2 5. Red light fogging Corning 2403 filter 2.5 millimeters distance 1000 micro-watt second per sq cm 6. Cyan developer 2 minutes 0 seconds 100°F± 0.1 7. Wash 2 minutes 100°F± 0.1 8. Blue light fogging Fish-Schuman LB3 2.2 millimeters distance 230micro-watt second per sq cm 9. Yellow Developer 4 minutes 0 seconds 100°F± 0.1 10. Wash 2 minutes 100°F± 0.1 11. Magenta developer + chemical foggient 100°F± 0.1 12. Wash 2 minutes 100°F± 0.1 13. Conditioner 1 minute 0 seconds ambient temperature 14. Bleach 5 minutes 0 seconds 100°F± 0.1 15. Fixer 3 minutes 0 seconds 100°F± 0.1 16. Wash 2 minutes 100°F± 0.1 17. Rinse 1 minute 0 seconds ambient temperature 18. Dry 105°F ± 5

Next - I was technical manager for Eckerd Drugs (2000 drug stores Southeast USA). Built 7 photofinishing plants each sized 20,000 rolls of film a day. Began installing one-hour labs in drug stores. Next worked as Technical Information Manager Noritsu. All and all, 55+ years in the photo business.

Photo Labs followed the United States Postal Laws regarding Pornography. It was against the law to return photographs that included images of "private parts". Photo Labs inspected every printed picture. This inspection was truly for quality control. Each print was custom adjusted by automatic printers. As each frame was printed, the printer operator was able to see the negative or slide before the exposure was made. This afforded the opportunity for the operator to intervene and apply a manual correction. The back-printing applied to the back of the print recorded the amount and color offset of both the automated and/or the manual correction for density and color. Each finished print went to a high-speed inspection station and was examined. Off-Color prints were flagged for reprinting. The back-printing was consulted, and a revised manual correction was applied. At the inspection station, any print that was deemed to violate the Postal Laws was discarded. The film associated with this print was returned to the customer. Slide film and movie film was also inspected. Again, the primary reason was to double check the quality of the work, not to catch porn. If porn films were discovered, they were put in a safe for 1 year and then destroyed. A letter was sent to the film's owner; they could come to the lab and retrieve orders that could not be sent back by mail. Per -- what was porn? It was up to the discretion of the workers at the lab to make this determination. A Supreme Court Justice had published -- "I can't always describe in words porn, but I know it when I see it". This is true - One experienced inspector, if porn was seen, went to a Catholic Church across the street and said some "Hail Mary's"

I was discharged from the U.S. Air Force in 1960. I went to school at Kodak Marketing Education Center -- Kodachrome School -- received life-long certificate to make and process and make and sell the equipment of the process. First job was with 3M making a knock-off called Dynachrome. I was a photofinisher for 55 years. I loved every minute!

@ BeBu Lamar -- I stand on my answer - To further illuminate - Focus Breathing is an observed change in angle-of-view induced when the lens is focusing on different distances. In other words, a change in magnification when focusing different subject distance. As you focus on different distances, the back focus changes. Not to be confused with focal length, a measurement made when the object being imaged is at infinity. At infinity, light rays arrive parallel. At closer distances light rays arrive diverging. I will concede, that being 84 I could be wrong and outdated.

“Lens Breathing – Focus Breathing” --- As you know, the job of the camera lens is to project an image of the outside world onto the surface of film or digital image sensor. To achieve, light rays from the subject (vista) traverse the lens. The figure (shape) of the lens and the density of the glass forces these rays to change their direction of travel. This action is called “refraction”, Latin to bend backwards. We can draw a diagram showing the revised path of these rays. Such a drawing is called a ray trace. Such a trace reveals the path of the light as it traverses the lens. Such a ray trace from a single image point resembles two ice cream cones place pointy end to pointy end. When we focus, we are adjusting the distance lens to sensitized surface. When the sensitized surface just kisses the apex of the cones, focus is achieved. It a fact that the distance lens to apex is a variable based on subject distance. The apex of this cone of light is at its shortest if the object is at infinity (about 3000X the focal length of the lens. Objects that are closer than infinity will generate a longer cone of light (increased back focus distance). Now the size of the image of objects is a function of their distance from the lens. Objects that are close generate longer cones of light. Objects at infinity generate the shortest projection distance. Thus, the size of the projected image of an object is proportional to this projection distance. As we focus our camera, we are adjusting the distance lens to projected image. Since the size of the image of an object change with projection distance, we will likely notice that image size (magnification) changes somewhat as we focus. This phenomenon is called “focus breathing”. Focus breathing is often considered disturbing in the motion picture trade as it is viewed as disrupting the smoothness of a zoom. In Cine photography some zoom lenses have a correction applied that minimize focus breathing. In still photography, focus breathing is likely moot.

As you know, color films are fabricated by sandwiching black & white film emulsions on a single base. Separate layers record, red light radiated by the scene is recorded on one layer, another records the blue and still another the green light. During developing, these layers laydown black & white metallic silver images. As developing proceeds, cyan (blue+green) dye is deposited in the red recording layer in proportion to the amount of silver present in that layer. Likewise yellow dye is deposited in the blue layer and magenta (red+blue) is deposited in the green layer. After this dye laydown, all the silver is dissolved away. Now all still camera films except Kodachrome have these dyes pre-loaded in the film during manufacturing. These films are called “incorporated” color films. The dyes used are incomplete, in fact they are colorless or nearly colorless (“leuco” state Greek for white). All three dyes need just one missing ingredient, and it is contained in the color developer solution. During processing these three dyes receive this missing ingredient in proportion to the amount of silver laydown in that layer. Upon receipt, they blossom into a full-blown dye. This clever method simplifies the developing process as compared to Kodachrome which requires three sperate color developing steps. Finding three dyes of appropriate color that are transparent and change state to brilliant is next to impossible. A tip of the hat to Kodak who is the author. Sorry to report that the only dyes that work this way are organic and thus fugitive (fade over time). Early incorporated films were rinsed in formaldehyde that slowed the fading. Labeled a carcinogenic it was removed and replaced with a biocide. In other words, organic dyes will in time fade, all we can do is admire them for a time. The goal, archival films with a half-life of about 100 years. Any misstep in processing reduces longevity.

Surf the web for motion picture film cleaners. Any product you buy, test first. I have used Everclear from the liquor store - nearly 200 proof alcohol (near 100% ethyl alcohol) works for me in every case. (you can drink if all goes south). As to paper developer temperature, 68 F 20C is the norm, no harm if hotter or colder is used except timeif in solution is altered. Best you use at ambient room temperature and develop under safelight by inspection. Biggest danger is too short time, results in mottled tones and low contrast.

I’ve been doing this stuff since I was 10 and I am now 84. The technique of rubbing and stroking print paper while in the developer works. I know because I learned this trick from my mentor (long dead). During development, the developer fluid must infuse into the emulsion. The emulsion is silver salts imbedded in gelatin. When the material enters the developer, which is mainly water, the dry gelatin expands, much like a dry sponge plunged into water. This action opens the gelatin structure allowing fluids to enter and percolate about. Print paper is developed under a quite bright amber safelight thus one can develop by inspection. There are a plethora of ways to locally retard or accelerate the developing action. Observing that an area is not developing up as desired, we often resorted to rubbing that area vigorously. I did this with bare hand, I almost never wore gloves. This works! I often lifted the print and rubbed underdeveloped areas with my fingers dipped into stock-solution (3X concentrated). An explanation: Photo materials absorb the developer, and it goes to work. The developer in situ, in highly exposed areas works quickly thus it exhausts quickly. In the normal scheme of things, agitation accelerates the expelling of spent developer and the influx of fresh. A vigorous rub will quicken this action. As to the staining of the hands. I learned early, your hands will not likely stain if you follow though. In other words, your fingers won’t stain if they go with the print into the stop and then the fix and wash. I have known many a darkroom worker with stained fingernails (looks unsightly). In all those years, mine never stained and I almost never wore gloves. Stupid me! However, I made it to 84 – black & white and color formulas. No dermatitis ever! Lucky for me. However, I always educated others on the need to dawn protective gear. I managed 7 giant photofinishing labs each handling 20,000 rolls a day. Employees safety and the environment first always.

A polarizing filter is most beneficial in that it mitigates reflections, increases saturation and contrast without impairing a color cast, makes clouds more vibrant, acts as a neutral density filter. It cuts haze because it filters UV. Early scientists trying to comprehend the double image they saw through a transparent Islandic Spar filter, wrongly assumed light had a north and south pole -- somewhat like a magnet. They labeled this action polarization; too late to change this name now. Light photons travel following a wave motion pattern. Unlike water waves that ungulate up then down, light waves vibrate in all possible planes (unpolarized). These waves can become polarized (vibrating in restricted planes) after being reflected from some surfaces and/or traversing some transparent materials. The polarizing filter acts like prison bars in that light waves can only navigate through, if the direction of vibration matches up with alignment of the bars. We adjust the polarizer for a desired effect by rotating it prior to snapping the shot. Sorry to report that polarized rays can interfere with some of the automation of a modern camera (both digital and film). This interference is on a case-by-case basis; better to err on the side of caution. We mount a circular polarizer in lieu of a simple linear polarizer. The circular polarizer is actually two filters sandwiched together. The upfront filter is a standard linear, the behind filter is called a “retarder”. The retarder undoes the polarization so that the exposing light has no impact on the camera’s automation. However, the upfront linear has done its deed, so we get the full influence of the polarization filter.