Printing on Translucent (‘vellum’) papers

Detail, Moti Malde with Drape and Kiran Malde, Sewanee, 2015. Platinum-palladium (1:1) on Reich CT Clear from original 8×10 negative [see full image]

Here are some notes on the use of ‘vellum’, or more properly, translucent papers for platinum/palladium printing. The two papers mentioned below have been used very successfully with my preferred process of print-out platinum-palladium, but they have some peculiar traits which require special consideration. The note may also be relevant to other hand-sensitized photographic printing processes.

Both the papers mentioned here are ‘naturally’ translucent through physical action, as opposed to the more common practice of manufacturing a transparent paper by chemical means as used in the manufacture of most vellums. (Ultimately, there is a fine line between chemical and physical action, and I hope scientists will forgive this clumsy distinction.) This technique requires a lot of cellular defibrillation at the beating/refining stage of paper making, and results in a highly cross-linked and dense sheet.  The papers have been sized for the reprographic / printing industry (no more details are available at this point), and lean towards the acidic end of the ‘acid-free’, pH 6.5 to 7.0, designation. Note that the resulting platinum/palladium prints are archivally sound and pH neutral after being processed through the recommended clearing baths.

The most readily available paper in the USA currently is the CT Clear offered by the family-owned Reich (pronounced ‘reesh’) Paper Company in New York. The paper has been made to Reich’s specifications since the early 1990s, by a paper mill in the United Kingdom. It may be purchased directly from the company. Described on the company web site as a paper that is made from “superfine, pristine cellulose” furnish, CT Clear is available in a variety of weights, the most workable being the thickest 48# or 5.7 point. It is pure enough to have been approved for wrapping food by the FDA (and is an excellent ‘parchment’ paper for baking). Reich CT Clear #48 is my most preferred paper: it has good wet strength, and renders prints with an almost fibre-free surface, strong maximum blacks (around 1.4), and warm to neutral tones. Thinner variants of this paper also work with the process, but require much more careful handling when wet.

Wyndstone vellum paper Wyndstone Vellum 5 point, item #165243 is believed to be manufactured in Germany, and distributed in the USA as a rebrand under the Wyndstone name through graphic and paper supply companies such as Hyatts.com. Furnish is wood cellulose,  The US distributor insists that the paper is lignin free, even though its furnish is wood cellulose using a mixture of hard and soft woods, including some eucalyptus. Thinner variants of this paper also work with the process, but require much more careful handling when wet.

Cutting
Full sheet = 25 x 38 inches (other sizes may be available)
May be cut to:
12.5 x 19 (4 pieces per full sheet)
10.75 x 12.75 (6 pieces per full sheet)
9.5 x 12.5 (8 pieces per full sheet)

Coating
While it may be hardly apparent when looking at the dry, uncoated paper, there is a wire and a felt side that will show up with slightly different characteristics once the print is dry. It is difficult to determine which side is which with the naked eye. When cutting down the full sheet, stack all paper with the same side up. Thus, once you make a first print from the stack, it will be possible to identify surfaces by the way the stack lies. Another, more subtle indicator comes from the curl of the paper: the felt surface is the convex side. I recommend coating the wire surface or convex side.

To coat a 8×10 inch area, 1.3 mL of solution is ideal, allowing for 4 to 6 passes with a glass coating rod. More sensitizer may be necessary if coating with a brush. The paper is less absorbent than other papers. The addition of 0.02 (about 1 drop) of Tween 20 (6% dilution) to this amount of sensitizer assists in absorbency and helps to render a more homogenous range of lighter tonal values. Once damp, the paper tends to curl dramatically. A simple method of preventing unmanageable curling, from this point on through to drying, is to attach two clothes pegs to the lower end of the paper. The pegs themselves are attached to a ‘cross-piece’ of 3/16″ dowel or plexiglass tube. This structure tends to hold the paper relatively flat during drying. A similar arrangement can be used for the top end of the paper too.

Drying
Drying times may be as those normally used for other papers. However, special care is needed since translucent papers tend to cockle.

Exposure
Assessing image formation during exposure, due to the paper’s translucency, is best done by having a piece of white paper or thin card handy as you prepare to inspect. Slipping it between the coated paper and the negative will make assessment easier. I have also found that it helps to place the contact printing frame face down on a white surface – as I swing the back open and lift the negative, the image projecting through the translucent paper gives me enough information to make rough estimates of exposure. At full print-out, highlight values (zones VII – VIII) are still difficult to see, They will only become apparent once the paper is dry and sitting on an opaque white surface.

Note that UV will pass through the paper during exposure, and will reflect off the surface underneath and arrive back onto the sensitized surface. This affects exposure. It certainly has a greater effect on print-out processes than development-up processes. In other words, if exposures for print-out processes are made on a white (reflective) support, the ‘self-masking’ effect will be greater than with a black (relatively less reflective) support. Pay attention to this behavior as you determine the best arrangement.

Processing
The thicker papers are very robust and have good wet strength. However, they tend to kink easily, therefore should be handled with about the same care as with papers lighter than about 160gsm.

Process as normal, finishing with a 20-30m wash in a very gentle flow of water.

Final Drying

Dimensional Stability – When immersed in liquid, translucent papers expand, mostly in the cross-grain direction, by as much as 20%. Once dry, there is shrinkage but not to the original dimensions: the paper ends up about 4% longer than the original sheet dimensions in the cross-grain direction, and frustratingly, shrinks in the grain direction by 1 to 2%. This has to do with the intrinsic nature of cellulose fibers and the way these papers are made (extensive ‘beating’ and no fillers or internal sizing agents) – it may be a worthy tradeoff for purity. More notes on this matter are forthcoming.

Generally, after processing and the final wash, consider drying under a weighted board, between sheets of blotting paper that are changed frequently until the prints are dry. Note that the blotting paper should always be very clean and used only for this purpose. If needed, prints may be further flattened in a dry mounting press at around 60-65C for a few minutes. If a press is not available, press under weighted boards for a day or so.

A more specific method, based on a print having been immersed in liquids for a total time of between 1 to 2 hours could be:
i. After the final wash, drain the print on a near-vertical, clean sheet of glass or plexiglass for 5-10 minutes (be consistent)
ii. Place the print between two sheets of dry blotting paper which are between boards under about 0.5Kg/cm2 of evenly distributed weight. Change the blotters every 30 minutes, repeating this step for a total of 4 times. The print will feel almost dry at the end of this cycle.
iii. Either press the print between dry blotters under a weighted board for 24 hours, or between museum boards in a dry-mounting press at 60-65C for 10 minutes.

Reich CT Clear

Wyndstone Vellum

See also my list of Resources for Platinum/Palladium Printing