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Collotype – Overview
Category: alt photo
Alt Papers: getting stuff
In new country may mean new clothes. Printing and printmaking are different. They began in different places, and diverged into different schools — education of the doers. Some of the words may sound the same. They aren’t.
Works on paper is the big arch. The base of the image is a paper, that very old fundamental object. It is quite nice on its own. So nice, that many are makers of paper; done. that is all that is needed. Make the paper. Show the paper.
Others, most of us, put something onto that paper. Photographic prints are on very limited range of papers. Hand-coated emulsions extend that range, as does digital printing. In fact, many digital printmakers chose that method because of the range of paper surfaces. Some of the most ardent devotees of the chemical cult do so because they dislike, disapprove of the paper surfacing above the plastic sheen of 20th Century Gloss.
Look List:
- https://legionpaper.com/
- https://www.acuitypapers.com/
- https://www.talasonline.com/paper-and-board/fine-art/printmaking
- https://www.imcclains.com/catalog/paper/index.html
- https://www.takachpaper.com/
- https://www.graphicchemical.com/
- https://www.utrechtart.com/categories/paper-boards/printmaking/
- https://www.washiarts.com/
- https://ruscombepaper.com/uk/
- https://www.johnpurcell.net/
- https://store.bookbinding.co.uk/store/
- https://www.dickblick.com/
- https://www.freestylephoto.com/
- https://www.bostick-sullivan.com/
| Paper | Process | Comment |
|---|---|---|
| Hahnemuhle Platinum Rag (HPR) | Platinum | Use as delivered |
| Arches Platine 300gsm | Platinum | “” |
| Bergger Cot 320gsm | Platinum | “” |
| Legion Revere Platinum | Platinum | “” |
| Clearprint 1020HP | Inexpensive 100% cotton | |
| Arches En Tout Cas | one side hot pressed, one side eggshell textured | |
| Awagami Platinum Gampi | ||
| Hahnemühle Sumi-e: | ||
| Legion Thai Kozo | coat with brush. | |
| Canson Vidalon Vellum | ||
| Canson Opalux Vellum | ||
| Rives BFK 280gsm | gum /pigment | my first paper for litho back in school. for alt prints requires acidification. |
| Fabriano Artistico | gum prints | requires acidification |
These are papers that are proven to work well across processes. find a vendor, then get samples to test in your work conditions. Your water, workroom conditions of temperature and humidity. How well they dry. How well they coat. How well, and comfortable you are in their use.
One size rarely suits all printmakers. Chemical Printers are confined to accepting that which is commercially, meaning widely acceptable. That is, the “classic” look of “air-dried” gelatin. Or, the commercial Glass Gloss display print. They don’t have much choice. As a printmaker, you do. Make the most of that …
friday: Collected Maybe
many small readings. short hand notes.
st/ages of theory: how-to / what / why
learning from the hobby lobby means you may never know a reason. you probably won’t ask them questions, after-all, you and they are just hanging onto each other’s opinion. You will never ask where he saw that work. Unless you remember, because you were a member of the academy, you wouldn’t realize that geography was a strong barrier to exhibitions in the 70s and 80s.
Dichromated Gelatin
ask the other camps. look in books and journals. maybe google has a bigger, better memory than you realize.
The advantages of Dichromated Gelatin over Silver Halides are:
- More efficient recording material.
- Has less scattering.
- Is more transparent.
as dichromate is exposed absorption spectra changes.
the broader the exposure spectrum, the deeper the hardening reaction.
characteristics are listed below.
- Initial thickness of the gelatin layer
- Initial hardness of the gelatin
- Concentration of sensitizing dichromate bath
- Drying conditions: temperature, humidity, and time
- Exposure, wavelength and energy
- Time delay between exposure and processing
- Alkalinity and temperature of processing baths
- Composition of processing baths
- Time in processing baths
- Recording geometry
Factors Influencing Light Geometry
(a) Size of the light source. The larger a source, the greater becomes the angle of light rays travelling from its edges and therefore the degree of undercutting.
(b) Position of the light source. The nearer a light source is to the vacuum frame the greater is its effective size. Conversely if the lamp is moved further away, so its effective size is reduced. It is good practice to increase lamp distance when exposing very fine detail work to reduce the effect of light undercutting if at all practical, (do not forget that the exposure time will have to be adjusted if an integrator is not fitted).
the “printing out” tanning is similar in contrast effect as the “developing out” of tanning developers. DAS / Dichromate systems share the exposure effect: judge by depth of “cure” — tanning, hardening of the colloid. DAS exposure should begin with 365nm wavelength.
Absorbance and sensitivity are different. This is partial explanation for why color of exposing light should be broader with a longer (more depth) exposure requirement.
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