| Experience using aquatint screens (Mike Clements & Denise Fordyce) |
| The value of Trugrain films as screens (Julia Clements) |
| Film-backed photopolymer plate (Mike Clements & Inge Wright) |
| Edinburgh Printmakers (Alfons Bytautas, senior etching technician) |
| Brasso, Newsprint & Elbow Grease (Gordon Yapp) |
| Graining Glass (Group experience, 17 May 2004) |
| Wait until the Sun Shines! (Group experience) |
| Double Exposure intaglio Prints (Mike Clements) |
| Don't skimp on test Strips (Mike Clements) |
| Cutting Solar Plate (Denise Fordyce) |
| Lessons I learnt the hard way! (Mike Clements) |
Experience using aquatint screens: We have tried two different kinds of aquatint screen:
- From the USA. These seem to have a dense dot pattern and need to be exposed for about as long as the film transparency.
- From Edinburgh Printmakers. These seem to have a less dense dot structure and Alfons, the senior technician there, recommends that the screen exposure should be twice as long as exposure for the original film transparency. Our experience supports this.
So, please adjust your screen exposure times to reflect whichever kind of screen you have.
Our preferred order is film transparency first followed by aquatint screen. Don’t forget that you simply expose the film transparency first, then immediately replace it with the screen and expose again. Only after the double exposure should you wash out, dry and post-harden the plate in sunlight or light box.
The value of Trugrain films as screens: Those who were able to attend Alfons' workshop will recall that he extolled the virtues of Trugrain film for negatives for intaglio plates, which he said produced better results than any other drawing film because of its distinct grain. This is particularly the case for single exposure intaglio plates. He has discovered that it is unnecessary to draw or print every image on Trugrain (which is more expensive than say drafting film or tracing paper) provided a clear sheet of Trugrain is added on top of the image film in the contact frame before exposure. The Trugrain can then be used time and time again.
This is just to confirm that my recent experience very much supports this. Adding a piece of Trugrain gave the fine lines in my golden section single exposure plate "Phi" enough tooth for the intaglio ink to hold relatively easily, In contrast, I’d had great difficulty getting the intaglio ink to hold in the grooves of the original single exposure plate made from a drawing on drafting film.
Trugrain isn’t available all that widely, so Mike says please feel free to ask if you can buy a piece from the Trust’s supplies (at cost price).
Film-backed Photopolymer Plate - Alfons Bytautas, the Senior Print Technician from Edinburgh Printmakers was able to shed further light on Inge Wright's experience with film-backed photopolymer plate. Although Alfons has never used the film-backed plate, he suggested that the excellent results Inge had achieved with single exposure intaglio plates were due more to Inge having (perhaps inadvertently) used "halftone" negatives with a grain structure similar to aquatint. Printed images scanned from published sources and our own scanned pictures can both be printed with Halftone or with "dithering" to give this grain structure. Think of this as similar to drawing with semi-opaque media like charcaol, litho crayon or pencil, all of which also create a granular line.
Alfons said Inge's excellent results using film-backed plate for single intaglio exposures are less likely to have anything to do with giving the back of the plate a short initial exposure (½-1min). What this will do is to start hardening the photopolymer from the bottom and thus (helpfully) limit the depth of intaglio grooves generated when the film is flipped over and given the main exposure with a single exposure intaglio image film transparency. Shallower grooves are more likely to hold intaglio ink easily when printing the plate. Steel-backed plate cannot, of course, be pre-exposed in this way from the back, so the film-backed plate does have this advantage.
Film-backed plate also has an important drawback: the film curls badly after exposure and has to to be fixed to a rigid backing. Mount card works well as a backing but may not be durable for a large number of impressions. Very thin metal plate, e.g. aluminium, would probably be even better. Inge has found that double-sided carpet tape (which is very thin and strongly adhesive) is an effective way to fix the plastic film to a backing.
So, film-backed plate has major practical disadvantages and one perhaps less important advantage. It also costs slightly more that steel-backed plate.
Edinburgh Printmakers
have been working with photopolymer for the past 10 years and have developed
hi-tech methods far beyond those to which we at the Sidney Nolan Trust (SNT) can
currently aspire. Users of this site may be interested to see the
information kindly sent us by the senior etching technician at Edinburgh
Printmakers, Alfons Bytautas. This information fall into three categories:
1. Information on solar platemaking
Edinburgh Printmakers (EPM) use the same kind of water-washable, steel-backed
photopolymer plate as SNT users. Whereas we have tried, two brands (BASF
Nyloprint & Toray), EPM prefer the Toyobo brand. Their information is
a more detailed version of Alfons Bytauatas' recent article in Printmaking
Today. Click here to view.
2. Information on using cheaper, un-backed
photopolymer sheet laminated on to traditional copper/zinc etching plates.
Using this film, EPM combine photopolymer with etching techniques or the plates
can be printed "non-etch" as a sort of home-made polymer plate.
The advantages are cost-effectiveness. The film is cheaper, so EPM can
work in an experimental way on a bigger scale without worrying too much about
the cost. When used "non-etch", the film can be stripped off off
the plate and new film re-applied to the copper/zinc plates. Unlike
solarplate, there is some chemistry involved in developing the plate but this is
simply a 1% alkaline solution made from household washing soda (which they say
is safe and cheap too). Click here to view.
3. General information on the safe printmaking methods
used at EPM. This is very much in line with the priorities adopted
at the SNT. Click here to view.
Brasso, Newsprint & Elbow Grease (Plate Tone & Hightlights) - Some brands of solar plate have a strongly matt surface and print with quite heavy plate tone. This is often attractive. It is, however, easy to remove excess plate tone by polishing the plate surface (once it has been post-exposed) using Brasso and newsprint. Even smoother plate surfaces can be produced by using fine (1000 grain) carborundum powder with the Brasso.
This technique can be used to produce high-lights in an image. It is important to mask any areas you do not want to lighten, e.g. with an off-cut of OHP film or even newsprint. You will also need to remove all traces of Brasso and carborundum after polishing and before printing.
Graining Glass - grained glass will accept most kinds of drawing implement, including crayon, pencil, felt tip pens, india ink and lithographic tusche. Clear glass is too shiny to take many of these media. The group has tried three alternative ways to grain, all giving slightly different effects:
- Sandblasting: this needs a special box usually available in art colleges and other workshops. Take advice from specialists about the fineness of the abrasive required for the quality of grain you require.
- Graining: this is well described and illustrated in Dan Weldon & Pauline Muir's book on solar plate "Printmaking in the Sun" pp 68-69. One member of our group got a fine graining with much less effort than he'd expected, using fine carborundum powder from "Intaglio Printmaker" in London. Remember that the second (top) piece of glass needs to be thicker plate glass with smooth, rounded edges to avoid cutting fingers. All glass needs either smoothed edges or masking tape protection. Most drawing materials gave excellent results when the grained plate was exposed on to BASF Nyloprint WS 94 plate (the grained glass doubles as both transparency and cover in a contact frame).
- Glass Etch spray: this is a spray can sold in craft shops and intended to give a decorative etched effect to glass. it's a surface treatment that can easily be removed. Two members of our group tried this and found it was easy to apply, dried quickly and gave an even surface after about four coats. One group member found that hard drawing materials - and over-enthusiastic use of a rubber tended to chip or remove the spray. Soft drawing materials such as a 6B graphite stick gave good results. Smudging the grahite was effective in leaving tonal areas on the upper surface. Exposure was relatively short . Detail reproduced well. Our conclusion is that spray etch leaves too fragile a surface for energetic hard-line drawing but has its place for softer images.
Most of the group taking part in the Sidney Nolan Trust's project have had similar experiences trying to expose solar plate on cloudy days, or days when the sun comes and goes unpredictably. Such exposures have often been unsuccessful and result in wasted plate. Our collective experience suggests that it is better to have patience and wait for a reliably sunny mid-day before exposing test strips and plates.
One member of our group, Gordon Yapp, argues that UV light is likely to be proportional to overall light intensity, which can be estimated using a camera light meter. The difference between overall light intensity on a bright sunny day and a cloudy one can often be two or more aperture stops on a camera. Each stop doubles (or halves) the light admitted to the camera lens. So logically, solar plate exposure on a dull day should be four times as long (assuming two aperture stops) or even eight or sixteen times as long (if three or four aperture stops).
Double Exposure Intaglio Prints
I’ve experimented with this and it really is straightforward. Click here to see an example. Double exposure is an intaglio solar plate technique comparable to aquatinting in traditional etching. It is suitable for:
- Continuous tone images, e.g. photographs
- Images with areas of tonal contrast, e.g. washes
- Images that have marks wider or bigger than single exposure intaglio techniques will render without "open bite"
For you experiments, the Trust has two aquatint screen sizes that you can use at The Rodd:
- 115 x 180mm
- 200 x 280mm
If you intend to experiment with these aquatint screens, follow the following image size guidelines in preparing your transparency and plate .
Image Size: choose a final (trimmed) size no greater than one of the aquatint screen sizes, i.e
- 115 x 180mm or
- 200 x280m
Image Transparency Size: make this marginally bigger, e.g.
- 120 x 185mm or
- 205 x285mm
Solar Plate Size: use an untrimmed sheet
- 150 x 220mm (half sheet) or
- 220 x 300 (full sheet)
Don't skimp on test Strips (by Mike Clements, 4 April 2004)
- When you're new to solar plate, always make a test strip. A strip 2-3cm wide is fine. First guess the exposure time based on whether it's winter or summer, the time of day and whether it's cloudy or sunny. For example, in spring, at mid-day and in sunny conditions, try 4 mins for an intaglio plate, several times longer for a relief plate.
- Avoid scratching your image film by adding a spare piece of film just larger than the test strip and/or by putting the film on the test strip emulsion side up.
- Position the image film so that a uniform, clearly patterned section of it covers the test strip.
- Then expose the test strip in 5 or 6 bands from (in this example) 2 to 6
mins. Use thick, opaque mount card to mask the bands.
- If the first test strip doesn't yield useful results, make another with different timings.
- If the light conditions change between test strip and plate exposure, it's safer to make another test strip than to guess and risk spoiling a full plate.
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Cutting Solar Plate (by Denise Fordyce, 3 April
2004) I was delighted to find solar plate easier to cut than expected. The equipment I used was: I worked on my kitchen table, kneeling on a high stool - the tabletop came to
about mid-thigh. Being short, I find this more comfortable than bending over
from standing. I found the protective film lifted from the test strips I was cutting, so I
used small pieces of masking tape to keep it in place. (webmaster's note: see also point 3 in technical note "Lessons
I learnt the hard way") Lessons I learnt the hard way! (by Mike
Clements, 26 March 2004)
test strip.