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Thursday, 10 December 2015

Arts & Humanities: Visual Arts: “Question: Ideas for raising money for a Fine Arts Field Trip?” plus 5 more

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Arts & Humanities: Visual Arts: “Question: Ideas for raising money for a Fine Arts Field Trip?” plus 5 more

Question: Ideas for raising money for a Fine Arts Field Trip?

Posted: 10 Dec 2015 10:22 AM PST

Not enough of a sure thing. I suggest you use some of the existing money to buy spray paint and stencils and go with a friend door to door charging $20 to paint the house number on the people's curb. You and your friend split the costs of materials, and split the profits. You can start off taking turns selling and painting, but if one of you emerges as much better at selling, then let them do all of that and the other person do all the painting.
Experiment with different prices @20, $15, $10. Whatever you can sell a decent amount of, but obviously if you settle for $10, you will have to do a lot more of them, and you might have to buy more paint.

Question: In proper analog photography, does the film need to be washed for 20 minutes?

Posted: 10 Dec 2015 10:21 AM PST

Photographic film and prints are coated with an emulsion made by suspending silver halogen (Swedish for salt maker) in a binder of unflavored gelatin. Gelatin is chosen because it is flexible, transparent, has low solubility and most of all permeable. By permeable, we mean the gelatin structure swells when wet allowing the chemicals of the developing process to perculate about. The last step which is drying, allows the gelatin to shrink back down to its original thickness.

The developer is able to identify exposed silver salts. These are reduced to a tuft of metallic silver. The halogen component is dissolved away into the developer which is mainly water. The tufts of metallic silver are opaque and these make up the image.

The next step is a brief bath in a mild acid. This is acetic acid, the active ingredient in vinegar. Development takes place in an alkaline solution so the acid stop bath arrests development in a split second. Many substitute a water bath for a minute or two. This works as well to arrest development but it's not as fast. Also, an acid stop bath increases the working life of the next solution which also contains acetic acid.

The third step is a bath in a fixer solution. The word fix means to render permanent. Since the developer (in the time allotted) only works on exposed silver salts, the film at this stage contains lots of unexposed and therefore un-reduced silver salts. These will be exposed if the film is brought out into the light. Additionally, these now exposed silver salts will eventually self-reduce. As they reduce they liberate metallic silver and this ruins the image; its fades to dark gray or black.

As I said, the fix solution dissolves away the unexposed and undeveloped silver salts. Now the film or paper only contains the metallic silver image imbedded in a gelatin binder. However, the fix solution can be one of two active ingredients, either sodium thiosulfate or ammonium thiosulfate. Both work the same but the latter works twice as fast.

When the film or paper leaves the fix bath, the fixer solution remains in the pores of the photo paper and in the structure of the gelatin binder. We must wash this spent fixer out of the film or paper. If we do not remove the spent fixer, its sulfur content will attack the tufts of silver that make up the image. Additionally, the fixer attack will stain the film or paper and the stain will not be uniform.

We wash film for 20 – 30 minutes to thoroughly remove any residual chemicals. If the material is paper prints we must wash longer. Double weight fiber paper takes 1 hour, single weight 30 minutes. Modern papers are coated with a plastic to prevent the paper from getting wet. These are called resin papers and they wash in 10 minutes or less.

During World War II the Navy used seawater to wash film and papers followed by a rinse in fresh water. It was found that a few seconds pre-soak in seawater shortened wash time in fresh water to 5 minutes or so. Today we use a fix clear or hypo clear solution as a pre-soak before washing (hypo is a nickname for fixer). These modern water/time savers came from the Navy and are still in use. The hypo clear solution consists of several salts and sometime peroxide. With these employed, wash time is super short.

Question: Want to see pitures of floods/inrandle wash?

Posted: 10 Dec 2015 09:31 AM PST

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