Nature printing

Nicolai Klimaszewski explains Auer’s nature print process with variations. The process can render a detailed continuous tone print of an object without using a camera.

Auers nature prints fernThe “Auer Nature Print” may be of interest to photographers for a couple of reasons. First, it can render a detailed continuous tone photographic likeness of an object without the use of a camera. Second, it is likely that Walter Woodbury utilized a key concept inherent in this process as the basis for creating the popular Woodburytype. This method of imaging also provides creative possibilities within the realm of alternative photographic processes.

As with many early processes, there are differing opinions as to origins. This article forwards the popular view that Alois Auer of Vienna invented the process in 1852, and that Henry Bradbury patented his version of the process in England in 1853. Within ten years the technique was made obsolete by improvements in the photomechanical printing industry, and essentially “Nature Printing” disappeared from use.

Alois Auer named his process “Naturselbstdruckes”, which translates into “Nature-printing”, and then logically the end product of this process would be referred to as a “Nature Print”. However, the popular contemporary use of both of these terms refer to a very different process wherein images are produced by inking items such as fish or leaves with a roller, then printing them onto paper through a process of light controlled rubbing, much like one would print a woodcut. The original 1850’s process of “Nature Printing” used an entirely different technique, producing a unique kind of image that possessed a photographic quality and a remarkable delicateness of tone. For the sake of clarity this article will use the term “Auer Nature Print” to refer to both the process and the product of the original 1850’s technique.

The original 1850’s “Auer nature print” process

1Relatively flat objects were favored; lace, leaves, seaweed, and ferns were cited as popular subjects.

2The subject was placed on a thick sheet of steel, and a thin sheet of lead was placed on top of it. A second thick sheet of steel was added above the lead sheet.

3A hydraulic press was used to exert great pressure on this 4-layer sandwich, deforming the lead to follow the forms of the subject. (This defies reason, that a cabbage leaf could imbed itself into the lead rather than being squeezed flat, but this is how it works). Some accounts state that the lead sheet was passed between rollers, but it is likely that rollers were used only with softer lead substitutes such as resin or gum.

4The lead sheet was removed from the press and turned over. The subject was peeled from the lead sheet to reveal a detailed cavity that contained a precise surface.

5The lead sheet was lightly oiled, and a warm mixture of pigmented gelatin was poured on the surface so as to slightly overfill the cavity.

6A sheet of stiff sized paper was placed face-down on the mold with light pressure so as to squeeze out all excess gelatin, and left in place until the gelatin cooled.

7The paper was carefully removed from the lead, taking the gelatin with it. Upon removal, the gelatin contained the same amount of relief as the original subject had. The gelatin was left to dry until all water evaporated, and the surface became flat.

8The edge of the paper was trimmed to the plate size to remove the excess gelatin that was squeezed out during step 6. Some prints from the 1850’s era utilized a primary impression via engraving to insert text, adding the image in a second printing.

Auer nature prints leafContemporary adaptions of the “Auer nature print” process

The problematic piece of equipment that is required to make “Auer Nature Prints” (as well as Woodburytype prints) is the hydraulic press. Presses that can exert the proper pressure are massive, heavy, and expensive. The two variants below utilize plaster molds instead of lead molds, eliminating the need for the hydraulic press. In fact, molds can be cast from a wide variety of materials ranging from rubber to epoxy.

Variant 1: Artsy and maybe messy

This low-tech approach doesn’t require any specialized equipment.

1Use a rigid and nonabsorbent substrate such as ¼ inch tempered masonite, or ¼ inch glass as the “working surface”.

2Arrange subjects that are relatively flat, then figure out a way to adhere them temporarily. PVA is a glue that works for a wide variety of surfaces, but other adhesives may be more appropriate for your particular subjects. Keep about a one-inch border around the perimeter of your “working surface” free of any subjects, as this is where the mold frame must fit snugly against the rigid substrate.

3Your finished composition must be sealed so that plaster will release from it. Absorbent surfaces, or surfaces with texture like hair, will be problematic (messy). Multiple coats of spray primer-sealer often suffice.

4Apply a wood frame along the edge of your “working surface” that will eventually contain the poured plaster. A height of two inches is plenty. Clamp this frame to your rigid substrate with spring clamps.

5The entire inside surface of both the arrangement of subjects and inside edges of the wood frame must be treated so as not to adhere to plaster. A dozen spray coats of “Pam” cooking spray, lightly brushed between applications works well. Silicone release agent or pottery soap can also be used.

6Mix a standard pottery plaster, de-air, and carefully pour into the wood framed area to a height of between one and two inches. Let it set and harden for a day.

7Strip off the wood frame, the substrate, and subjects that are imbedded in the plaster. Likely there will be “undercuts”. These areas must be removed from the plaster mold with a small knife or else they will tear the gelatin later.

8Seal the plaster mold with multiple coats of thinned varnish or shellac. Apply a release agent such as “Pam” or silicone and brush out lightly.

9Prepare a gelatin mixture. Mix standard unflavored Knox Gelatin according to the directions on the box but reduce the amount of water used to between 10-25 percent of the amount recommended. You will have to experiment to determine the correct amount of pigment to add to the gelatin. The objective is to achieve translucency so that the very thin areas appear as a very light color, but darken in the deeper areas of the mold. If the mixture is too opaque, the results will be disappointing.

10Cast the warm gelatin into the plaster mold after release agent has been applied. Overfill the mold slightly so that the gelatin sits above the surface a bit.

For a creative painterly experience, you can use clear unpigmented gelatin, then add a variety of watercolors right in the mold. Alternately, several prepared gelatins of different colors can be placed into the mold prior to printing. This method of applying color is called “a la poupee”. To allow a longer working time for the assembly of the colors in the mold, the mold may be preheated to between 150 and 200 degrees f, and a heat lamp may be used above the surface.

11Place a sheet of stiff sized paper face-down on the mold. Bend the paper slightly and use a rolling motion to push any air bubbles to the edges. Place a flat object, like glass, on top and allow the mixture to cool. After a couple of days, remove the glass on top of the paper. Do not attempt to remove the printed paper from the mold yet. Turn the mold and paper over so that the paper sits on a clean absorbent surface, such as layers of common blotter paper. If you have the patience to wait a week or more, you will get the best results when you remove the paper from the plaster mold.

12Turn the mold over and carefully pry the paper from the mold. If pieces of gelatin tear or are left in the mold, they can be adhered back onto the print with fresh clear gelatin applied by a small brush. Trim the messy edge. It may take several more weeks of drying before the print can withstand normal handling.

Auer nature prints fernVariant 2: More technical

A more pristine and more photographic image can be produced by utilizing a vacuum pump in the process. An inexpensive pump that can pull 15 or more inches of negative pressure will suffice, and low volume is acceptable. The use of the pump will eliminate “undercuts” in the plaster mold, will hold the subjects very flat against the rigid substrate without adhesive, and will eliminate the necessity of applying sealing and releasing agents on the subject.

1The rigid “working surface” will require a group of very fine holes to be placed near the outer edges. For example if this “working surface” is 16 x 20 inches, the holes would be centered along the edge of a drawn 12 x 16 inch rectangle, leaving a clear margin of 2 inches on all outside edges. These holes will be connected to a vacuum pump via a flexible hose. The most efficient way to produce such a “working surface” is to use two layers of 16 x 20 material, so that the first surface contains the holes through the face, and channels on the reverse side that run from each hole to the center. The second surface is drilled in the center and a fitting for a flexible hose is installed. The two surfaces will be glued together to hide the channels and prevent vacuum from leaking.

2The vacuum pump should have a bleed valve attached to it on the intake side, then a pressure gauge, then a flexible hose that connects to the “working surface”.

3Arrange the subjects on the face of the “working surface”, being careful to maintain a one-inch clear perimeter.

4Lightly dust the subjects with talc or Baby Powder. Place a very thin sheet of silicone or latex over the subjects. This sheet should be slightly larger than the rigid “working surface”.

5Clamp a wood frame on top that will trap and seal the edges of the sheet. The wood should be about two inches tall, varnished, and treated with silicone release agent. The silicone sheet or latex sheet does not require any release agent.

6Turn on the vacuum pump to pull the elastic sheet down tight on the subject. Confirm that no wrinkles are developing and that the vacuum is not so high as to pull the elastic sheet under the subject (creating undercuts). On very flat subjects this is never a problem, but as subjects increase in height the vacuum pressure may have to be reduced by use of the bleed valve.

7Mix a standard pottery plaster, de-air, and carefully pour into the mold.

8Maintain the vacuum until the plaster has set and resists marking with a fingernail, then turn off the vacuum, but allow the plaster mold to sit undisturbed overnight.

9Disassemble the wood frame, the elastic sheet will release easily leaving a very clean plaster casting. Dry the plaster then seal with multiple coats of thinned varnish or shellac. Apply two coats of spray silicone release agent, lightly brushing after each application.

10Prepare a gelatin mixture. Mix standard unflavored Knox Gelatin according to the directions on the box but reduce the amount of water used to between 10-25 percent of the amount recommended. You will have to experiment to determine the correct amount of pigment to add to the gelatin. The object is to achieve translucency so that the very thin areas appear as a very light color, but darken in the deeper areas of the mold. If the mixture is too opaque, the results will be disappointing.

11Cast the warm gelatin into the plaster mold after release agent has been applied. Overfill the mold so that the gelatin sits above the surface a bit.

For multiple colors in a single printing, you can use clear gelatin, then add a variety of watercolors right in the mold for a creative effect, or use several prepared gelatins of different colors. This method of applying color is called “a la poupee”. The mold may be warmed to allow a longer working time for the assembly of the colors, and a heat lamp may be used above the surface.

12Place a sheet of stiff sized paper face-down on the mold. Bend the paper slightly and use a rolling motion to push any air bubbles to the edges. Place a flat object, like glass, on top and allow the mixture to cool. After a couple of days, remove the glass on top of the paper. Do not attempt to remove the paper from the mold yet. Turn the mold and paper over so that the paper sits on a clean absorbent surface, such as layers of blotter paper. If you have the patience to wait a week or more, you will get the best results when you remove the paper from the plaster mold.

13Turn the mold over and carefully pry the paper from the mold. If pieces of gelatin tear or are left in the mold, they can be adhered back onto the print with fresh clear gelatin applied by a small brush. Trim the messy edge. It may take several more weeks of drying before the print can withstand normal handling.

That’s the basic procedure. My article on Woodbury Process, which is closely related, may provide additional insight into understanding the workflow, and may offer some creative imaging applications in materials other than paper, such as clay and glass.



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