THE FILM

The prints on this page were all created using a 150, halftone,gray, negative, contact screen with an elliptical dot pattern or a 150 equivalent mezzotint contact screen and Ortho film. Exposures were made on a large format process camera producing a negative image. Since my intent was an intaglio print I then made a positive contact image by placing the negative halftone face down over a fresh piece of film on the camera's vacuum back board and used the flashing light to make the exposure.

If you are not familiar with this process, exposures can be divided into three parts - remember you are shooting a negative. The MAIN exposure, shot through the camera lens is generally calibrated to produce a tiny white dot on a black field at the light end of gray scale (off white or about 1.0 on a gray scale) and a small black dot on a transparent field at the dark gray end of the scale (1.50 or 60). This exposure will produce a latent dot pattern all the way up to 2.00 on the scale but it will not be visible or usable if not developed further. To do that the camera vacuum back is opened, leaving the contact screen in place, and exposed with a flashing light - The FLASH exposure. The Flash exposure will bring up tiny black dots in the shadow end of the gray scale and is very important to creating dark gray and black tones in an intaglio print. The third exposure is called a BUMP exposure. It is rarely needed but will create a slight fog at the light end of the value scale and produces a clear transparent area in the image which when later etched into the plate will print white. It is sometime useful for increasing the contrast in an image. Negative halftone screens have a built in fog or BUMP making it unnecessary to use this step in most cases the procedure for making a BUMP exposure is as follows: Place the film on the camera vacuum back emulsion side up. Close the camera and make a very short exposure. Open the camera back and lay in the halftone contact screen before making your MAIN exposure. The MAIN, FLASH or BUMP exposures can be made in any order. Today, of course, many printmakers are using computers making this process obsolete but if you do not have access to expensive image setters to refine the dot pattern this process will produce a finer quality halftone than can be achieved with the average inkjet or laser printer.

The film is developed in a two part A & B Ortho film developer, Stop bath and Fixer (rapid or regular) and washed.

LIGHT SENSITIVE EMULSIONS AND APPLICATION PROCEDURE

Early prints in this series were made using presensitized plates or KPR. Both required strong toxic developers and were abandoned after we discovered Super Vyna-Top, a water based emulsion that is without fumes. Ammonium Dichromate is used in the emulsion for light hardening (a toxic agent) so it important to wear rubber gloves when executing this procedure. The formula for mixing the emulsion is 20 parts Vyna-Top to 1 part ammonium dichromate. After mixing filter the emulsion it through a filter provided by the company to remove an particles and set aside.

Next clean the plate. This emulsion works best on zinc plates. Scrub, and I mean SCRUB, the plate three time with pumice or a good powered cleanser, a rag and water, rinsing with warm water after each scrubbing. Keep the plate covered with warm water - do not let it dry as oxidation which begins immediately will tend to reject the emulsion.

The emulsion may be applied by poring or by spinning it on in a whirler. Since you may not have a whirler I will only mention the simplest means - pouring. Wearing rubber gloves, pore some of the emulsion into the water on the plate using it to gradually push the water off the plate. Add a bit more and work it around allowing it to run off the corners to make an even coating. Place the coated plate under a infrared heat lamp (approximately 12") in a dark place to dry. The emulsion does not become light sensitive until it is dry.

EXPOSURE

Exposure time will vary with the light source used. The light source may anything from a sophisticated xenon lamp and vacuum frame to a 500 watt photoflood lamp hung over a drawing board covered with a sheet of plate glass to the sun. You will have to run some tests to determine the correct exposure time but whatever you do make sure the halftone film is emulsion to emulsion with the sensitized plate and intimately contacted. Since the sensitizing agent is ammonium dichromate you will see an image when you remove the plate from it light source

DEVELOPING THE PLATE

To develop the plate simple run tepid water over it for about two minutes. The image will become more visible.

FIXING THE IMAGE

Dip the plate in a hardening solution for 20 to 30 seconds. Rinse with cool water until all the yellow coloring (dichromate) disappears. Wear rubber gloves. Place the plate on a hotplate preheated to 450 degrees for about 10 minutes or until the emulsion becomes a dark chocolate color. The plate is now ready to etch.

ETCHING THE PLATE

Etch the zinc plate in a weak nitric acid solution (16 parts water to 1 part acid). A four to five minute etch should give you the full range of tones, although your blacks may appear a little thin. The plate may need careful stopping out and further etching or other manipulation to achieve rich blacks.

PROOFING

I would recommend proofing the plate with the emulsion on it. If further etching is need it is then easy to do.

REMOVING THE EMULSION

If you plan to add aquatints or softground textures it necessary to remove the emulsion. There is only one way to do that successfully and it involved toxic fumes and should only be done under a good fume hood and wearing a fume mask and rubber gloves. Place the plate on a hotplate preheated to 450 degrees and spray liberally with Easy Off Oven Cleaner. It helps to cover the plate with a metal tray if you have one. Allow to stand for a minute. respray. You will notice that the emulsion has turned to a dull black. remove the plate from the hotplate, take to a sink and spray with cold water. Most of the emulsion will flack off. use a powdered cleanser and a rag to remove anything remaining and to polish the plate.