Step away from the instant gratification of digital clicks and delve into a photographic world where texture, pigment, and patience reign supreme. Gum bichromate printing isn’t just a method; it’s an artistic journey back to the roots of photography, offering unparalleled control and a distinctly painterly aesthetic. This historical process, dating back to the mid-19th century, allows creators to imbue their images with a handcrafted quality, transforming photographs into unique, tactile artworks that resonate with the touch of the artist’s hand.
Understanding the Magic: What is Gum Bichromate?
At its core, gum bichromate is a contact printing process based on the light-sensitive properties of dichromates when mixed with a colloid, in this case, gum arabic. Think of it as creating your own photographic emulsion, tailored precisely to your vision. The essential ingredients are surprisingly simple, yet their interaction forms the basis of this versatile technique:
- Gum Arabic: A natural gum harvested from acacia trees. It acts as the binder, holding the pigment and forming the image during processing.
- Pigment: Typically watercolor paints or pure powdered pigments. This is where the color comes in! The choice of pigment directly influences the hue, saturation, and permanence of the final print.
- Sensitizer: Usually ammonium dichromate or potassium dichromate. This chemical makes the gum arabic sensitive to ultraviolet (UV) light.
When these three components are mixed together with water, they form a light-sensitive coating. This mixture is brushed onto a suitable paper support. When exposed to UV light through a negative, the areas hit by light harden the gum arabic proportionally. The more light that passes through the negative (the highlights of the image), the harder the pigmented gum becomes. Areas receiving less or no light (the shadows) remain relatively soft and water-soluble.
The Gum Printing Process: A Step-by-Step Exploration
Creating a gum print is a methodical, multi-stage process that demands care and rewards precision. While variations exist, the fundamental steps provide a roadmap for transforming a negative into a pigmented artwork.
H3: Preparing the Foundation: Paper and Sizing
Not just any paper will do. Gum printing requires a robust, dimensionally stable paper, typically a heavyweight watercolor or printmaking paper that can withstand multiple exposures and soakings in water without disintegrating or excessive shrinking/stretching. Before applying the light-sensitive emulsion, the paper must be ‘sized’. Sizing involves applying a hardening agent, like gelatin, starch, or a synthetic sizing agent, to the paper surface and allowing it to dry completely. This crucial step prevents the pigments from staining the paper fibers directly and provides a better surface for the gum emulsion to adhere to, allowing for clearer highlights and richer shadows, especially when working with multiple layers.
H3: Mixing and Coating the Emulsion
This is where art meets chemistry. The gum arabic solution, pigment, and dichromate sensitizer are carefully measured and mixed. The ratio of these components influences contrast, exposure time, and the final appearance. Too much pigment can make the emulsion difficult to clear in the wash; too little results in weak colors. The mixed emulsion is then brushed onto the sized paper as evenly as possible, usually under dim, non-UV lighting conditions. A wide, soft brush (like a hake brush) is often used. Achieving a smooth, even coat without streaks takes practice and is vital for a clean print. The coated paper is then left to dry thoroughly in complete darkness.
Safety First! Ammonium and potassium dichromate are toxic and potential carcinogens. Always handle these chemicals with appropriate precautions, including wearing nitrile gloves, eye protection, and a dust mask when handling powders. Work in a well-ventilated area and dispose of waste chemicals responsibly according to local regulations. Avoid ingestion and skin contact.
H3: The Moment of Truth: Exposure
Once dry, the sensitized paper is ready for exposure. A negative (the same size as the desired final print) is placed emulsion-side down directly onto the coated paper. This sandwich is typically secured in a contact printing frame. Exposure is made using a UV light source – traditionally sunlight, but now more commonly UV lamps or exposure units which offer greater consistency. Exposure times vary significantly based on the density of the negative, the specific emulsion mix, the strength of the UV source, and the desired effect. Determining the correct exposure often involves test strips and careful record-keeping.
H3: Revealing the Image: Development
Development is deceptively simple: the exposed print is gently submerged in a tray of room-temperature water. The magic happens as the unexposed, unhardened gum arabic and pigment slowly dissolve and wash away, revealing the image. The areas that received the most UV light remain hardened and hold onto the paper. Development can range from a passive soak, allowing the water to do the work, to more active manipulation using gentle currents of water, soft brushes, or sponges to selectively remove pigment or emphasize textures. Water temperature also plays a role; warmer water speeds up development and can soften even partially hardened gum, offering another layer of control.
H3: Building Depth: Multiple Printings
A single gum bichromate layer often appears delicate, lacking the density of a traditional photograph. The true power and unique beauty of the process often lie in multiple printings. The print is dried, re-sized if necessary, re-coated (often with a slightly different color mix or density), carefully registered with the negative again, re-exposed, and re-developed. This layering process allows the artist to build rich, deep shadows, introduce complex color combinations (by using different pigments for each layer), and achieve a luminosity and depth unattainable with a single pass. Each subsequent layer adds to the previous one, creating a complex, interwoven tapestry of pigment on paper.
The Enduring Appeal: Why Choose Gum Bichromate?
In an age of digital perfection, why embrace such a labor-intensive, analogue process? The attraction lies in its unique characteristics and the creative freedom it offers.
A Painterly Aesthetic: Gum prints inherently possess a soft, slightly diffused look. The pigment sits physically on the paper’s surface, often retaining the texture of the brushstrokes used for coating. This creates an image that feels less like a direct reproduction and more like a watercolor, pastel, or drawing – a truly painterly photograph.
Unmatched Creative Control: From mixing custom pigment colors to manipulating the development process with brushes or water streams, the artist’s hand is present at every stage. Gum printing is an interpretative process, allowing for significant deviation from the original negative to match the artist’s intent. Color palettes can range from monochromatic to full, vibrant spectrums built through careful layering.
Inherent Uniqueness: Due to the subtle variations in coating, exposure, development manipulation, and registration between layers, no two gum prints are ever exactly identical, even when made from the same negative. Each print is essentially a monoprint, a unique object d’art.
Archival Stability: When executed with high-quality, lightfast pigments on archival paper and processed correctly, gum bichromate prints boast excellent longevity, rivaling other historical processes and potentially outlasting many contemporary digital print methods.
Tactile Connection: The entire process is profoundly hands-on. Feeling the paper, mixing the emulsion, brushing it on, watching the image emerge in the water bath – it fosters a deep connection between the artist, the materials, and the final image that is often lost in purely digital workflows.
A Rich History, A Vibrant Present
Gum bichromate emerged in the 1850s, building on earlier discoveries about the light sensitivity of dichromates. It truly flourished during the Pictorialist movement of the late 19th and early 20th centuries. Photographers like Robert Demachy, Constant Puyo, and Alfred Stieglitz embraced gum printing (and related processes like bromoil) to assert photography’s status as a fine art, emphasizing artistic interpretation over mere documentation. They valued the painterly qualities and the manual control that allowed them to create expressive, atmospheric images.
While falling out of mainstream favor with the rise of modernism and gelatin silver printing, gum bichromate never truly disappeared. Today, it enjoys a resurgence among fine art photographers and printmakers seeking alternative, hands-on techniques. Contemporary artists continue to push the boundaries of the medium, combining it with digital negatives, exploring new pigment combinations, and integrating it with other art forms.
Exploring gum bichromate printing is undoubtedly a commitment. It requires patience, experimentation, and a willingness to embrace imperfection. There’s a definite learning curve, and initial results may be frustrating. Yet, for those drawn to its unique aesthetic, its historical resonance, and the deep satisfaction of crafting an image with one’s own hands, the rewards are immense. It offers a path away from the pixel-perfect and towards the personally expressive, transforming photography into a truly painterly pursuit.
