lightpotions

Prior to coating and exposing I shrink the paper in 120°+ water for 30 minutes.

In using Ware’s cyanotype formula [Cyanotype II] my current method is to dilute the stock sensitizer with equal parts distilled water (to reduce the density and intensity of prussian blue) before adding a drop of 40% citric acid for every 2 mil. of total sensitizer solution. I had previously been adding a drop of 40% citric acid per every 1 mil. of sensitizer (this is what the instructions from Photographer’s Formulary  & Ware’s website recommended when I first ordered the kit; since that time I have been mixing from bulk chemicals). My understanding is that the addition of citric acid reduces contrast in the cyanotype print and helps the sensitizer ‘accept’ a wider range of papers; Ware’s cyanotype is more finicky regarding paper choice. I had started using Tween 20 with Bergger Cot-320 as I experienced an uneven, blotchy appearance — a result of incomplete absorption into the hard surface of the paper perhaps? I have since eliminated the surfactant because of the difficulty removing the unexposed sensitizer from the paper during the wash — if not removed pockets of residual sensitizer will ‘print out’ when exposed to UV light resulting in density spots (on the subject of spots, Ware’s cyanotype also causes a sort of graininess to the print when it becomes old or is contaminated). Now I am more thorough with brush coating and am rewarded with even coating and appearance.

After brush coating my paper thoroughly horizontally, vertically, and then horizontally again (being patient and slow — there are no awards for fast, sloppy coating), I allow it to air-dry for around an hour, or so with a room fan blowing gently on the coated paper. I then expose the paper using a Pictorico OHP negative and a vacuum press — usually, for around 70-80 seconds (My goal in a cyanotype print is to produce a slightly underprinted, low contrast base in order to layer with subsequent gum passes to achieve an aggregate print that exhibits a full tonal range with adequate contrast — I consider the color provided by the gum process to be essential to my goals).

I then develop the print immediately in 70° water. After a minute, I change the water and rinse for another minute. If the yellow-green sensitizer is no longer visible I then remove the print from the water and, after changing the water again, I add a splash of hydrogen peroxide and swish it around well before adding the print back to the water for 30 seconds. I change the water again after this and continue washing for around 20 minutes (Ware writes, “20 minute wash” on his website).

After the print is completely dry I tape it across all edges to masonite and apply Gamblin PVA size thoroughly with a stiff bristle brush. I have learned that the PVA as it dries attempts to contract [shrink] the paper which,  of course causes problems with registration of gum negatives; taping across all edges to rigid masonite mostly solves this problem. The size prevents gum pigments from staining the naked paper surface.

Now I am ready for my first pass of gum bichromate…