Thursday, July 9, 2009

Gum and negatives with a twist of Français

Peter Blackburn shows how variables in gum printing can alter the desired outcome of your negatives.

Before you get too excited, this article does not describe a bizarre new apéritif to be served before your favorite pot au feu. Neither will it be a treatise complete with screen shots outlining the latest PhotoShop curve for gum printing. Rather, this petit essay is designed to serve as a simple reminder or an item for consideration as to the practical, somewhat nebulous nature of contact negatives in gum work. Kindly allow me to make the following three statements for our brief examination:

* First, while contact negatives provide crucial information useful for rendering desired tonality, negatives are not necessarily the last word in creating that tonality.
* Second, while contact negatives provide essential information for image composition (structure) and definition, negatives do not necessarily provide the last word on structure and definition.
* Third, while contact negatives (those used in three and four color printing) provide information which when combined create a color rendering, negatives can not necessarily claim the last word for color output.

Here are a few preliminary notes before we begin. In all of the examples provided for this article, I have not added any additional size to my papers. If your practice is to add supplemental size, such as gelatine, the principles described below might be reflected differently in your work. Although French-made pigments and papers were selected for comparison, country of origin is incidental to the purpose of this article. The same set of negatives (all examples below are from paper negatives) were engaged for each series of examples. Finally, I avail myself to most of the products mentioned in this essay for specific purposes in my work. Feel free to try them for yourself if they can be acquired where you live.

Now — in celebration of the famous French gummist, Robert Demachy, let's take a look at those three points mentioned above as if we were discussing the matter while lounging in the amphitheatre of the Palais Garnier over a hot cup of café noisette.

Danse de deux papiers

A cold press, AKD-sized, Montval brand paper (left) and a hot press, traditional-sized Arches brand paper are compared in the above examples. The same set of pigments which do not stain my AKD papers were applied in both images. Note how paper texture and paper sizing can affect tonality, definition, even color balance. Although adding additional size, such as gelatine for example, to the Arches paper would minimize staining and provide a smoother tonality, staining and grain can be useful effects for certain pieces. As a rule, I do not add additional size to my papers. On the occasions when I do, I use AKD (alkyl ketene dimer).

Danse de deux rapports de gomme

My normal 1:1 ratio of gum to potassium dichromate is applied in an entirely gouache tricolor gum print on the left. To the right, I've increased the gum ratio to 1.5:1 and made a slight pigment adjustment. Both were printed on my usual Fabriano paper. Observe the subtle difference in tonality, structure, and definition. Making proportion adjustments in your gum/dichromate mixtures can change mood and expression. In the case above, we have shifted from a defined image (left) to a more distressed, moody concept just by changing gum proportions.

Danse de trois ensambles de colorants—corps de ballet

Above we see a different trio of French pigments dance their way through their own interpretive performance. One image above is all Sennelier, one is all Linel, and another print contains The French School pigments — I'll let you guess which print reflects which brand. The point here is that your choice of pigments and how they are combined, your chosen concentration, and a myriad of other factors (exposure, sizing, paper quality) can produce an image which significantly deviates from the intended color scheme applied at the PhotoShop stage. Through testing and tweaking, it is possible to create gum photographs which come fairly close to matching the original or intended colors. However, if you desire the more precise accuracy of say, the Pantone system, well, good luck with that.

Different pigments, whether watercolor, gouache, dry powder, or other forms, can all vary your color output in balance, saturation, and even finish. For example, gouache prints tend to dry with a flat finish while watercolor works can display a bit of a sparkle. Gouache images, on the other hand, are usually more color saturated than watercolor prints. Fillers, binders, pigment purity, and pigment concentration in tube paints can also play a role in hue and stain.

Adjustments - Curves OR Dodge and Burn Tools?
It's a Matter of Liberté

Whether printing negatives on high quality transparency material, translucent paper, or other media, there seems to be a great emphasis in gum printing circles of exploiting the curve feature in Photoshop. While I agree it is an appropriate tool which can easily help you to achieve a certain image quality, one that I would describe in many cases as homogenous, applying curves is only one among several approaches to excellent work.

And while it's true — gum curves which flatten images seem to do a great job of revealing shadow detail thereby helping to extend the tonal range of a print — it is done, in my view, at the expense of highlights, most notably specular or pinpoint highlights. I do not employ the flat negative viewpoint reflected in many (not all) gum curves for my work, preferring a bit more dynamic and contrast in the overall look. Expressed another way, I usually desire more visible cream (bright highlights) and curd (chunks of choice blacks).

Being both a graphic designer and photographer now for many years, I often seek bold, frame-filling, even frame-bleeding images which exhibit some dense blacks and bright whites along with a range of desired tones — and that's the key phrase, desired tones. Making sure that those tones carry through to the printed sheet is an objective which can be achieved through applying careful photographic skills and through a detailed interaction with the image in PhotoShop. It's there that I deliberately select which parts to dodge, burn, or make contrast adjustments to fit my interpretation for any given piece. With that stated, I am confident there are additional creative approaches to producing negatives and matrices for gum printing which are just as rewarding, just as masterly. Surely one size, or in this case, one method might not fit all. As someone who is very pragmatic in my printing approach, I especially encourage the beginning gum printer to explore and pursue all intriguing avenues to discover the appropriate negative preparation which meets your own printing objectives.

With these two images (see the article on, I've simply switched gum arabic with casein as the binder/vehicle. The look is similar to gum but the process is far easier and much faster depending upon how the casein is produced and handled. The same negatives created for gum can be used for casein.
C'est la vie

In conclusion, if you're like me and have been printing for any length of time, you probably cherish a certain paper or two, stock a favorite set of pigments, and rely upon a basic gum ratio, keeping all of those factors in mind when you photograph and create your negatives whether in Photoshop or in the darkroom. In time, you begin to develop a unique style, while eventually moving on to explore other gum expressions. How merveilleuxis it to know that with just one set of negatives, you can create a variety of moods, a selection of styles, and a range of interpretations just by the switch of a paper, a pigment, or a proportion?

Happy gum printing — may all of your work express that certain je ne sais quoi! Merci beaucoup.

Note: Casein pigment printing and gum bichromate printing in my work is almost identical in method. Casein and gum are simply switched with each other. My form of casein work should not be confused with other forms where casein is combined with salt printing, Van Dyke, and others.

See the complete article, with all the great examples of images on:

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