The Science Behind Making a B&W Darkroom Print
PHOTO PAPER EMULSION Contact and enlarging darkroom papers have a light-sensitive coating called, emulsion. The emulsion that you can’t see with your eye is silver halides suspended on a gelatin coating. Photo paper actually contains a mixture of silver halides and this is what responds to your light source and darkens when the paper when exposed. Halides are a group of elements consisting of bromine, chlorine, iodine and fluorine and their corresponding salts are what we refer to as “halides”. These halides are referred to as bromide, chloride, iodide, and fluoride. I will explain this in more detail below, however, the key part you should take away if nothing else is that silver halides are the magic ingredients in your photo paper and films.
The light-sensitive silver halide emulsion layer has a silver content of approximately 1.7 g/m2. The emulsion is covered with a gelatine supercoat which protects the emulsion from stress fogging and physical damage and also contains a small amount of developing agent. Silver Chloride papers are considered to be very slow papers and they are not suited to be used as an enlargement paper. Kodak AZO is the best-known paper and is no longer in production. Chloride emulsions are fine-grained and are considered to be warm and brown-black in color. This fact alone may direct or steer you away from this paper based on your artistic goals. I create emulsions by hand and coat my own paper negatives and printing papers. The knowledge in this article is critical to understand in order to be able to do these types of things. Historically silver chloride was combined with silver bromide and therefore called “bromochloride” for neutral tone papers they were “chlorobromide” for warm-tone papers. The only known silver chloride paper available today is Lodima Silver Chloride available exclusively via Michael A. Smith via his website. The other option is to make your own emulsions and coat your papers by hand like I do. Silver iodide is used in very small amounts in some papers in combination with bromide and chloride to modify the paper’s properties and characteristics. LET THERE BE LIGHT
THE DEVELOPER The latent image that was exposed with your negative and light source is now ready to be developed and darkened on your paper. The development step is where the “magic” happens for many people. You can literally see the image appear in front of your eyes. Your developer chemical is actually changing the invisible silver halides into grains of metallic black silver resulting in the image you see with your eyes. As you may have figured out the developer only acts on the silver halides that were exposed to light. Now you have those magical particles of silver suspended in the gelatin emulsion. We need to stop the development from continuing. STOP BATH
THE FIXER Remember that only the silver halides that received enough light were converted to metallic silver by the developer as discussed above. For example, your highlights and shadows received much less light because your negative was denser in these areas. Because of this your paper still has undeveloped silver halides and if you have white borders on your print from a frame, mask, etc. then there is a significant amount of silver halides still on the paper. We must remove these halides or they will expose or print out over time. Removing these halides is the job of your fixer. Your fixer will dissolve the halides but now you need to wash them away. DOING THE WASH After we have completed the fixing step we need to literally wash away the dissolved silver halides. Depending on the type of paper and archival intentions the washing time and technique will vary. SUMMARY I hope this article has given you a better understanding of the science that is taking place when you are printing your masterpieces in the darkroom. This knowledge will serve you well in many different ways. When you read the technical specifications on your darkroom paper of choice this information should make more sense to you now. There are many other more advanced variables to discuss such as toning, bleaching, redeveloping and others at a later time. Video Workshops For Analog Photographers Read Testimonials from photographers and collectors from around the world. Buy Your Film, Darkroom, and Photography Gear at No Additional Cost To You From B&H Photo COLOR FILMS, DEVELOPERS, DARKROOM GEAR Fujichrome Provia 100F - Fujichrome Velvia 100 - Fujichrome Velvia 50 - Kodak Portra 160 - Kodak Portra 400 - Kodak Ektar 100 - Fujicolor Pro 400H - Fujicolor Crystal Archive Silver Gelatin RA4 Paper - RA-4 Color Print Processing Developer & Processing Chemicals - Color Darkroom Enlargers ILFORD B&W FILMS & DEVELOPERS Ilford HP5 Plus- Ilford FP4 Plus - Ilford Delta 100 - Ilford Delta 400 - Ilford Delta 3200 - Ilford Pan F Plus - Ilford XP2 Super - Ilford SFX - Ilford ID-11 - Ilford DD-X - Ilford Microphen KODAK B&W FILM DEVELOPERS Kodak Tri-X - Kodak T-Max 100 - Kodak T-Max 400 - Kodak Portra 160 - Kodak Portra 400 - Kodak Ektar 100 - Kodak P-3200 - Kodak Ektachrome - Kodak D-76 - Kodak XTOL - Kodak HC-110 DARKROOM SUPPLIES & EQUIPMENT Note: I participate in affiliate programs where I earn a small commission on some select products that I provide links for on my website at www.timlaytonfineart.com. When you use these links, I earn a small commission and there is no additional charge to you.
Comments
No comments posted.
Loading...
|
