EP - Prints

	Lithography research at Edinburgh Printmakers Interactions Folio of lithographs by twelve artists, 2003 Research of lithography processes has focused on the main materials used at EP: Stone, Aluminium photo plate and polyester lithography. Although ball-grained zinc is also used occasionally at EP there is less demand for this material and it has become an increasingly expensive to have plate grained and supplied. Stone lithography Materials for airbrush and spray tints on stone Drawing materials for monotype transfers Photocopy and digital laser print transfers to stone Coated transfer paper Maniere noire and reduction techniques Chemical image removal Aluminium photo plates Controlled developing methods for aluminium photo plates Multiple exposure techniques for image control with Alu. Photo plates Digital separations for photo plates Negative working photo plates Recycled Aluminium photo plates Image removal and surface preparation to re-use Aluminium photo plates Direct image making and drawing materials for recycled Alu. Photo plates Waterless lithography using recycled Alu photo plates Polyester plates Digitally created polyester plate lithographs Printing techniques for polyester plates Drawing materials for polyester plates Surface printing drawing materials and relief printing of polyester plates Cleaning stones with stripper solution Stone is by far the most popular litho material used at Edinburgh Printmakers. As stone grinding can be labour intensive and risk creating uneven stones, a common practice here is to remove images chemically using stripper solution. The solution used is an alkali cleaner –Speed Stripper, made by Johnsons, which attacks the greasy content of the drawing without harming the stones’ surface. A clear advantage of using this method in preference to grinding is the ability to retain a ‘ghost image’ which is very useful for registration when working in colour. Procedure 1. After printing wet wash-out the image to remove as much ink as possible from the stone, finishing with a damp sponge. 2. Move the stone to the graining sink. (Large stones may be cleaned at the bench, providing care is taken not to spill speed-stripper or excess water onto the bench. A respirator should be worn.) 3. Wearing gloves and goggles, pour a little stripper solution onto the image areas of the stone and allow it to stand for 5 minutes. After 5 minutes, rub with a green scouring-pad to dislodge the ink stain from the stone. Rinse well with water. If some noticeable ink stains remain, repeat this process. When ready the image should be noticeably lighter, and may even disappear. 4. After rinsing, re-sensitise the stone with Citric acid, twice for 1 minute, rinsing well with water in between applications, rinse, squeegee and dry. When dry a clear ghost image should remain, as a guide for drawing! Variations on this process As some types of drawing may stain the stone more permanently, a combination of chemical cleaning followed by some grinding is a common practice to ensure thorough image removal. This practice will usually remove any remaining ghost image and surface imperfections due to etching/ scraping etc. This practice is still far less work than stone grinding alone! Procedure 1. Remove the previous image chemically with stripper solution (steps1-3 above) 2. Grind with 150 grit (once or twice depending on the image-stain) 3. Finish with 220 grit. A final rinse with citric acid will ensure all chemical and gum-stain is removed. Health and safety: Skin irritant, Eye Irritant, Corrosive Johnsons Speed stripper is an alkali floor cleaner which is corrosive and should be used in a well ventilated area. Gloves and goggles should be worn at all times when working with stripper solution. Recycled Aluminium photo plates David Faithfull - Tornado:Flight Crash Investigation, Aluminium photo plate Lithograph, plates exposed to digital separations output onto acetate, plates printed by hand Introduction Originally manufactured for the printing industry, these lightweight aluminium plates are pre-coated with a light-sensitive emulsion. As an extension to the printmakers vocabulary, photo-plates offer a fast, easy way of preparing an image to print, the image is very durable and can be stored indefinitely for future printing. Conventional photo plates: a brief processing Summary The drawing is first made on acetate with opaque drawing materials. The acetate is then placed in contact with the plate, exposed to ultra-violet light and developed under safe-light conditions. During development the emulsion lifts away from the white areas, leaving a positive image of blue- emulsion. After gumming, the plate is printed as normal with the blue emulsion acting as an ‘ink-base’. Both positive and negative plates are used at Edinburgh Printmakers. Recycling plates Aluminium photo plates are normally used once and then discarded. However it is possible to remove the photographic image completely leaving a fresh surface which can be used for surface process lithography using permanent (non water soluble materials). This offers another range of mark making possibilities from conventional grained plate or stone lithography and is especially useful for preparing plates for background colours etc. It is an extra free life from the plate! Plate preparation - After printing clean ink off well after printing and sponge off any remaining solvent etc with water. - clean of all the image emulsion using the plate developer - Rinse off then sponge with citric acid, ‘ rinse, reapply rinse well and blot dry. The following materials can then be used to add marks to the plates: Marker pens- Pentel N50, Staedtler lumocolour - permanent S318, biro pens Acrylic paint - (not flow formula acrylics) Acrylic impasto mediums. Photocopy transfers with winter green straw hat and shellac mix for solid brushwork straw hat varnish and meths washes Gouache and gum lifts Spray paint and airbrushed acrylic. Process summary Once dry the plate is given a coat of Gum Arabic with a sponge and buffed down with scrim. Washes and photocopies should be etched with mid strength plate etch. The etch is dried for 30 minutes before printing. The plate is printed with the drawing materials still on the plate - this is a process known as surface printing. To print, the image is sponged and rolled up with ink. Washes are best sponged over with mid-plate etch just before printing to keep tones clean. To print flat brushwork and solid marker pen lines, prime the plate with ink diluted with white spirit prior to inking. For all other materials don’t prime before printing and keep the ink on the slab stiff and lean. Polyester plate lithography Keith Thompson, Tomographical survey #3, Polyester Lithograph and screenprint Creating Images on the Plates with a Laser-printer or Photocopier. In the printing industry, images are transferred to polyester plates by running the plate through a laser-printer or photocopier. This creates a durable toner-image on the plate which forms the ‘ink- base’. This is the fastest and easiest application of the plate and as it requires no further processing or chemicals treatment before printing, it is incredibly quick to prepare an image to print. Images will print darker than that on the plate so it is important to lighten the over all image to compensate for this factor. When using a digital output simply adjust the values of the image prior to putting the plate through the printer. With a copier adjust the light to dark settings. Drawing Materials for surface printing Straw hat for solid brushwork, straw hat varnish and meths washes. Straw hat, being a shellac based varnish dries rapidly producing a tough durable mark. If layers are overlapped after drying, a visible layering will be visible as the hard shellac rolls up as a relief-mark. Soft washes can be produced by wetting the plate with meths and adding straw-hat onto this. Brushing water or gum arabic into this wet solution will produce white marks or outlines, depending on how much the varnish has dried. white spirit will cause the varnish to repel, gouache will create crazing and globules. Health and Safety Straw hat is an unpleasant material which gives off strong fumes, it should be used in a well ventilated area. At Edinburgh Printmakers, when it is occasionally used as a drawing material for surface lithography, it is used in an area with a local vent hood. Acrylic paint - (not flow formula acrylics), Acrylic impasto mediums Acrylic paint can be used to create solid brushmarks, and if painted thickly some impasto effects can be achieved as the paint will roll up as a relief print. This effect can be heightened by adding acrylic mediums to the paint such as Liquitex acr ylic texture gel- modelling paste. With a hog hair brush this can produce unusually three- dimensional impasto brush effects. Gouache and gum lifts Gouache lifts- Paint the gouache onto the plate, diluting with more water to leave only edges or use neat to block out solid marks. Once dry: 1. Apply straw hat/ meths mixture. Any streakiness of the coating will show so this can be used to creative effect. ie add dribbles and spatters etc, dry and add a second layer of dry brushing, paint over certain areas more to block out the background as a solid. 2. Air dry the straw hat varnish for 3 minutes then lift the gouache by placing the plate in atray of cold water, sponging. 3. Apply mid strength plate etch, sponge over for two minutes, buff dry with scrim. 4. Allow the plate to dry t for 30 minutes. Prime with inkthinned with solvent, then sponge the plate and ink with a hard roller and stiff/ lean ink Spray paint and airbrushed acrylic Spray paint can be used to create tones and gradations, areas can be masked with gum arabic or gouache prior to spraying or masked between layers of spray to create tonal mar ks and shapes. Borders can be masked with gum or masking tape. When applying sprays take-care- SPRAY VERY SPARINGLY, check tone by peeling tape of margin to compare. Expect the spray to print darker than it appears. Sprays that have been used- Acrylic varnish (Klear) coloured with flow formula acrylic. Water can be used to paint into, lift off and create spatters during the drying of the spray. Halfords Satin black. - very fine spray, visible, easy to judge tone. Plasti kote- white Kitchen enamel spray. Lifts off from plate gradually unless well dried (and heated) prior to printing.- White colour is harder to judge when spraying, but easier to see the ink film when inking. Photocopy transfers Good quality, fresh, dark photocopies will produce fine transfers using winter green oil as a solvent. This can be done through the press for consistent large areas or burnished by hand. The winter green should be evaporated (under the ventilation hood preferably) before the toner is dried and hardened by heating this in the drying cabinet for 2 hours (or longer if possible). Once the toner is hardened, etch the plate with mid-plate etch and buff dry with scrim. Do not prime photocopies prior to printing- just sponge and roll up. Printing ‘Surface material’ lithographs When printing washes/ sprays etc - stiffen the ink well with Mag, keep the ink on the slab thin, use a hard roller and roll fast and light. Conversely to block in washes without leaving detail, use a loose ink, with thicker ink on the slab and a soft roller, roll slowly applying pressure.