Condensed Milk and Photo-
Sensitized Silkscreens


By Devora Neumark *
                                                                 
The following technique was developed and perfected over some years with input and advice from many individuals.  I learned this process from the knowledgeable personnel at the Atelier de L'ile, Val David (Quebec), who had picked it up from professors at Concordia University, Montreal (Quebec).  It is offered as a safe, effective alternative to the conventional process of photo-etching using highly toxic solvents.  The procedure combines the use of photo-silkscreen emulsions and techniques with the "sugarlift" technique of classic etching.  This article is written for the artist who already has knowledge of both silkscreen and etching processes.
 
List of Required Materials
An apron or smock; gloves for acid; chemical splash goggles; a test image (8" x 10" maximum) on acetate or high contrast Kodalith (not dot screen); 2 cleaned zinc or copper plates; a silkscreen; liquid silkscreen photoemulsion (e.g. Ulano-TZ); squeegees; spray adhesive; an exposure light source; Borden Brand condensed milk; black China ink (optional); 2 pieces of cardboard the thickness of the plates, as long as the silkscreen, and 2 inches wide; liquid soft ground or Ultraflex; a soft, clean brush; a pan or sink for lifting the ground off the plate; a source of very hot water; a feather; Ulano photo-sensitive emulsion remover; and other printing supplies (ink, tarlatans, etching press, test and edition papers, etc.).
 
Procedure
While it is always somewhat difficult to master a complicated technical process without firsthand viewing, I will try to clarify the steps and offer tips that will lead to satisfactory results.  Some experimentation will probably be in order for the reader to become fully proficient in this technique.  Of course, you have to take all necessary safety precautions when using acids and spray adhesives.

    1.    In a darkroom, apply the photo-sensitive emulsion onto a clean, dry silkscreen (using a squeegee to achieve a thin even coating) at least one hour prior to working.  It often is more convenient to prepare the screen the night before.

    2.    Select the image and prepare the high contrast continuous tone Kodalith or photocopy acetate.  When selecting the image, it is important to keep in mind that while fine detail is possible to achieve, take care to avoid under-bites.  Reversing the image is also a factor to keep in mind when adhering the Kodalith or acetate to the screen.

    3.    In the darkroom, attach the Kodalith or photocopy acetate to the screen with spray adhesive, making sure the proper side faces the screen to allow for reversing the image once it is exposed, screened onto the plate, and finally printed.

    4.    Expose the screen under the fluorescent lights in a vacuum table, or use spotlights, sunlight, or ambient room light.  Test strips should be done to determine the proper time exposure.  The properly exposed image will be visible equally in the light and dark areas of the image.

    5.    Once the proper exposure is decided upon and achieved, gently (without pressure) wash the screen with warm water to remove the emulsion.  This step is complete when you can clearly see through the screen in the unfixed areas.

    6.    Place the screen on your work surface and place the etching plate precisely under the screened, exposed area of the image.  Place a cardboard slat on either side of the plate to protect the screen from the sharp edges of the metal plate.  It is vital to remember this step, otherwise you run the risk of seriously tearing or ripping your screen.  Mix a small amount of the black China Ink with the Borden Brand condensed milk for visibility, and apply with the squeegee as you would any silkscreen ink. 

You can refrigerate the condensed milk, but it must be applied at room temperature to obtain the proper consistency. Carefully and slowly lift the screen to check for proper coverage. (At this point, the plate might stick slightly to the screen; gently tap it at the corner to release the suction.)  If the coverage is not even and if the placement of the plate has not shifted, repeat the pass with the squeegee until the milk is evenly distributed.  If the plate shifts, or the milk layer becomes too dense, simply wash the plate off with warm water, dry thoroughly, and repeat this "inking" process.    
Assuming the exposure of the image was properly evaluated, you should get a near perfect resolution of your original image on the plate with the condensed milk.  DO NOT CLEAN YOUR SILKSCREEN YET.  Since you might want to repeat this transfer process, it is advisable to leave the photo screen as is until the acid biting stage is completed.

    7.    Allow the plate to dry for 2-3 hours, or until slightly tacky to the touch.  Do not allow the condensed milk to dry longer than this tacky stage, or it will not lift out in the next step.

    8.    Apply a thin coating of liquid soft ground or Ultraflex using a soft paint brush, and let dry.  Place the plate in a bath of hot water for copper plates or in boiling water for zinc plates to lift the condensed milk.

    9.    Place the plate in an acid bath of approximately 7:1 to bite, keeping a close eye on possible underbiting, and stirring the acid with the feather to prevent bubbles from collecting on the plate.

    10.    Proceed to work the plate (and print the image) as you would any other sugar lift plate, keeping in mind that if you choose to apply an aquatint, you must use aerosol spray paints since the heat needed to melt a rosin aquatint will also melt the soft ground.  You may work and rework the plate as many times as needed to obtain the desired results using hard ground, selective biting, aquatints, burnishing, etc.  When you are satisfied with the printed results, remove the photo-emulsion from the screen.

Once the technique is fully understood and practiced, larger images can be printed this way.  Limitations in size only depend on the etching press bed size, since multiple acetates can be used and combined.


 
* Devora Neumark is an artist and art hazards consultant in Montreal, Quebec, Canada.

Art Hazard News, Volume 16, No. 3, 1993



This article was originally printed for Art Hazard News, © copyright Center for Safety in the Arts 1993. It appears on nontoxicprint courtesy of the Health in the Arts Program, University of Illinois at Chicago, who have curated a collection of these articles from their archive which are still relevant to artists today.