Technical Journal – Photo-intaglio

Niepce​ ​invented​ ​a​ ​photomechanical​ ​process​ ​using​ ​a​ ​sensitised​ ​pewter​ ​plate.​ ​The images​ ​produced​ ​were​ ​called​ ​​heliographs.​ ​​Photogravure​ ​became​ ​the​ ​commercial process​ ​for​ ​reproduction​ ​in​ ​the​ ​late​ ​19th​ ​Century.

Photopolymer​ ​film​​ ​-​ ​UV​ ​light​ ​sensitive.​ ​Laminated​ ​onto​ ​any​ ​smooth​ ​surface.

Photo-intaglio​​ ​-​ ​Image​ ​is​ ​held​ ​in​ ​the​ ​photopolymer​ ​surface.

Steps​ ​for​ ​Positive​ ​Image​ ​on​ ​Transparency​ ​for​ ​Photo-intaglio
Before​ ​preparing​ ​the​ ​image​ ​in​ ​photoshop​ ​to​ ​make​ ​a​ ​positive​ ​transparency,​ ​ensure that​ ​it​ ​has​ ​been​ ​saved​ ​at​ ​300​ ​dpi.

  1. Open​​ image​​ in​​ Photoshop.​​​ Image>Mode>RGB​​Colour>16​​Bits/Channel​.
  2. Image>Mode>Grayscale​,​​ to ​​remove​​ colour.
  3. Clean ​​and ​​modify ​​the ​​image,​​ i.e.​​​ Image>Adjustments>Levels​​​ or Brightness/Contrast​.​ ​Resize​ ​to​ ​the​ ​dimensions​ ​you​ ​want​ ​the​ ​image​ ​printed.

    Image>Image​ ​Size​ ​​to​ ​set​ ​to​ ​15x21cms​ ​for​ ​this​ ​example.

  4. Edit>Convert​​ to ​​Profile>Grey​​ Gamma​​ 2.2 ​​​(Windows) ​​​Grey ​​Gamma​​ 1.8 (Mac)​ ​to​ ​increase​ ​tonal​ ​range.
  5. Image>Adjustments>Levels ​​​or​​​ Curves ​​​to​​ achieve​​ best ​​tonal​​ range.
  6. Flatten ​​image ​​if​​  necessary,​​​Layers>Flatten​​​  and​​ reconvert​​ to​​ 8-bit​​channel, Image>Mode>8/Bits​ ​Channel​ ​before​ ​printing​ ​the​ ​transparency.
  7. Print,​​​ File>Print ​​​select​​​ CC_Upper_Art_Xerox​​@​​bramley

Image​ ​preparation​ ​from​ ​drawings
The​ ​following​ ​can​ ​be​ ​used​ ​to​ ​create​ ​images:

  • ●  Mark​ ​resist​ ​film.​ ​Can​ ​use​ ​pencil,​ ​acrylic,​ ​guache​ ​etc
  • ●  Photocopies​ ​on​ ​acetate
  • ●  Scanned​ ​images​ ​output​ ​as​ ​half​ ​tones​ ​onto​ ​film

Plate​ ​Preparation
Cut​ ​plate​ ​to​ ​desired​ ​size​ ​and​ ​bevel​ ​the​ ​edges​ ​and​ ​corners​ ​with​ ​a​ ​file.​ ​Lightly​ ​file​ ​the back​ ​as​ ​well.

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Use​ ​electric​ ​sander​ ​to​ ​roughen/key​ ​the​ ​surface​ ​of​ ​the​ ​plate.

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Degrease​ ​the​ ​surface​ ​of​ ​the​ ​plate​ ​with​ ​detergent​ ​and​ ​water​ ​to​ ​neutralise,​ ​then​ ​rinse thoroughly​ ​with​ ​water.​ ​Dry​ ​the​ ​plate​ ​without​ ​touching​ ​the​ ​surface​ ​to​ ​ensure​ ​that​ ​the film​ ​will​ ​laminate​ ​properly.

IMAG2348

Laminating​ ​the​ ​Plate​ ​with​ ​Photopolymer​ ​Film
Avoid​ ​handling​ ​the​ ​film​ ​in​ ​direct​ ​sunlight​ ​and​ ​have​ ​a​ ​light-safe​ ​folder/box​ ​for​ ​the plates.​ ​The​ ​Etching​ ​Room​ ​has​ ​red​ ​darkroom​ ​lights.​ ​The​ ​film​ ​has​ ​3​ ​layers,​ ​a photosensitive​ ​layer​ ​sandwiched​ ​between​ ​two​ ​clear​ ​plastic​ ​layers.​ ​Set​ ​plate​ ​on​ ​some newsprint.​ ​Cut​ ​film​ ​slightly​ ​bigger​ ​than​ ​the​ ​plate.​ ​The​ ​film​ ​curls​ ​back​ ​on​ ​itself.​ ​From the​ ​inside​ ​of​ ​the​ ​curl,​ ​peel​ ​away​ ​the​ ​clear​ ​layer​ ​and​ ​then​ ​stick​ ​to​ ​the​ ​plate.​ ​Take​ ​the plate​ ​to​ ​the​ ​press,​ ​cover​ ​with​ ​the​ ​blankets​ ​and​ ​turn​ ​the​ ​press.

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Take​ ​plate​ ​and​ ​return​ ​to​ ​the​ ​darkroom,​ ​ensuring​ ​that​ ​the​ ​plates​ ​are​ ​light-safe,​ ​and trim​ ​the​ ​excess​ ​film​ ​of​ ​the​ ​plate​ ​with​ ​a​ ​scalpel.​ ​The​ ​return​ ​the​ ​plate​ ​to​ ​the​ ​light-safe box.

Exposing​ ​the​ ​Plate​ ​for​ ​Photo-intaglio
A​ ​test​ ​strip​ ​must​ ​be​ ​produced​ ​which​ ​will​ ​result​ ​in​ ​a​ ​more​ ​accurate​ ​way​ ​of establishing​ ​the​ ​correct​ ​exposure​ ​time.
Check​ ​the​ ​UV​ ​light​ ​unit​ ​has​ ​been​ ​switched​ ​on​ ​for​ ​at​ ​least​ ​five​ ​minutes​ ​to​ ​reach optimum​ ​strength.

1st​ ​Exposure
If​ ​the​ ​image​ ​does​ ​not​ ​have​ ​a​ ​halftone​ ​screen​ ​then​ ​you​ ​must​ ​expose​ ​an​ ​Aquatint screen​ ​onto​ ​the​ ​surface​ ​of​ ​the​ ​photopolymer.​ ​This​ ​will​ ​produce​ ​the​ ​midtones​ ​of​ ​the image.​ ​Carefully​ ​place​ ​aquatint​ ​screen​ ​emulsion​ ​side​ ​up,​ ​place​ ​plate​ ​face​ ​down​ ​onto the​ ​screen​ ​and​ ​cover​ ​with​ ​newsprint/blanket​ ​to​ ​protect​ ​the​ ​rubber​ ​vacuum​ ​frame.

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Close​ ​the​ ​frame​ ​and​ ​expose​ ​for​ ​5​ ​units.
5​ ​units​ ​is​ ​a​ ​good​ ​average​ ​for​ ​an​ ​image​ ​with​ ​various​ ​tonal​ ​makeup.

2nd​ ​Exposure
Check​ ​the​ ​test​ ​strip​ ​to​ ​establish​ ​the​ ​optimum​ ​time​ ​then​ ​set​ ​the​ ​UV​ ​to​ ​that​ ​time,​ ​in units.​ ​Place​ ​the​ ​transparency,​ ​right-reading,​ ​onto​ ​the​ ​glass​ ​of​ ​the​ ​exposure​ ​unit.​ ​The emulsion​ ​side​ ​of​ ​the​ ​image​ ​should​ ​be​ ​in​ ​direct​ ​contact​ ​with​ ​the​ ​plate.​ ​Put​ ​the​ ​plate

face-down​ ​onto​ ​the​ ​image,​ ​cover​ ​with​ ​newsprint/blanket,​ ​clamp​ ​down,​ ​switch​ ​on vacuum​ ​and​ ​expose​ ​the​ ​plate.

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Developing​ ​the​ ​Plate
Dissolve​ ​half​ ​a​ ​tablespoon​ ​of​ ​Sodium​ ​Carbonate​ ​(washing​ ​soda)​ ​in​ ​2​ ​litres​ ​of​ ​warm water.​ ​Remove​ ​the​ ​remaining​ ​plastic​ ​layer​ ​from​ ​the​ ​plate​ ​and​ ​place​ ​face​ ​up​ ​in​ ​the developer.​ ​Gently​ ​rub​ ​the​ ​surface​ ​of​ ​the​ ​plate​ ​with​ ​a​ ​sponge​ ​for​ ​2-3​ ​minutes.

​​IMAG2360 IMAG2364

Gently​ ​spray​ ​with​ ​vinegar​ ​to​ ​“Stop”​ ​the​ ​developer.​ ​Wash​ ​thoroughly​ ​and​ ​gently​ ​with cold​ ​water.​ ​Blot​ ​the​ ​plate,​ ​dry​ ​it​ ​quickly​ ​and​ ​thoroughly.
Post​ ​bake​ ​the​ ​plate​ ​or​ ​harden​ ​the​ ​plate​ ​under​ ​the​ ​UV​ ​for​ ​3-4​ ​units.

Printing​ ​the​ ​Plate
Clean​ ​the​ ​plate​ ​with​ ​a​ ​little​ ​vegetable​ ​oil​ ​to​ ​prevent​ ​the​ ​paper​ ​sticking​ ​to​ ​the​ ​plate.

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Ink​ ​the​ ​plate​ ​with​ ​the​ ​edge​ ​of​ ​thick​ ​cardboard.

​​IMAG2371 IMAG2372

Form​ ​an​ ​inking​ ​pad​ ​from​ ​scrap​ ​net​ ​curtains​ ​and​ ​press​ ​and​ ​twist​ ​into​ ​the​ ​inked surface​ ​of​ ​the​ ​plate​ ​to​ ​remove​ ​the​ ​ink​ ​form​ ​the​ ​non-etched​ ​part​ ​of​ ​the​ ​plate.

​​IMAG2373IMAG2375
Unfortunately​ ​on​ ​the​ ​left​ ​side​ ​of​ ​the​ ​plate​ ​there​ ​seems​ ​to​ ​be​ ​a​ ​cloudy​ ​texture. Something​ ​has​ ​gone​ ​wrong​ ​during​ ​the​ ​preparation​ ​of​ ​the​ ​plate.

We​ ​now​ ​plate​ ​the​ ​inked​ ​plates​ ​on​ ​the​ ​press​ ​with​ ​damp​ ​paper.​ ​The​ ​moisture​ ​of​ ​the paper​ ​will​ ​draw​ ​out​ ​the​ ​ink​ ​onto​ ​the​ ​paper.

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The​ ​cloudiness​ ​is​ ​visible​ ​on​ ​the​ ​right​ ​on​ ​the​ ​printed​ ​image.​ ​Slightly​ ​disappointed.

The​ ​plate​ ​can​ ​now​ ​be​ ​cleaned​ ​with​ ​vegetable​ ​oil​ ​(red​ ​spray)​ ​and​ ​detergent​ ​(blue spray).

​​IMAG2385 IMAG2386

Induction​ ​Reflection

This​ ​was​ ​an​ ​interesting​ ​and​ ​enjoyable​ ​induction​ ​although​ ​I​ ​cannot​ ​see​ ​how​ ​this technique​ ​work​ ​with​ ​glass.​ ​Intaglio​ ​ink​ ​is​ ​very​ ​viscose​ ​and​ ​needs​ ​moist​ ​paper​ ​to​ ​draw out​ ​the​ ​ink​ ​from​ ​the​ ​etched​ ​part​ ​of​ ​the​ ​plate.​ ​However,​ ​for​ ​the​ ​purpose​ ​of​ ​creating prints​ ​and​ ​collages​ ​as​ ​part​ ​of​ ​the​ ​creative​ ​process,​ ​this​ ​has​ ​a​ ​lot​ ​of​ ​potential.​ ​A​ ​scan could​ ​be​ ​made​ ​of​ ​the​ ​finished​ ​prints​ ​or​ ​alternatively​ ​just​ ​using​ ​screen​ ​printing​ ​as​ ​a method​ ​will​ ​save​ ​a​ ​lot​ ​of​ ​time.​ ​I​ ​am​ ​looking​ ​at​ ​etching​ ​directly​ ​onto​ ​glass​ ​in​ ​the FabLab​ ​using​ ​the​ ​laser​ ​cutter/etcher.

Posted in Blog - MA Glass.

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