Variations and more

Variations

The blueprint can be turned into a gray print by colouring it. It is best to do this after it has been fixed. Colouring is possible in a solution of tannic acid (web shop) of 1 gram per liter, but it is also possible with strong, cold, black tea. Rinse the blueprint in this solution for about ten minutes until the colouring has taken place.

Instead of Potassium ferricyanide red (T), Potassium ferrocyanide yellow (T) can be used, this gives a much darker colour with other contrasts.

There are several other options for further editing, we haven’t tried everything yet. Be aware that not everything works, don’t experiment with the most successful pieces, but make a lot of proofs.

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Especially if you want to learn more about printing from a transparency and editing it, a course or workshop is a good idea, for example at:

Defobie, in various places in the country. The Defobie website contains beautiful examples of what is possible with blueprints.

Polychrome, in Middelburg, also offers various other photochemical processes, such as carbon printing and salt printing.

Blueprint – making photosensitive paper

Blueprint or cyanotype is an old photographic technique that was mainly used for making copies of large technical drawings and plans. When you talk about a blueprint in everyday life, you usually mean a plan for something. With the advent of the photocopier and other inexpensive reproduction techniques, the blueprint disappeared. Fortunately, there are always people who are interested in these ancient techniques, purely out of curiosity or because of their artistic possibilities.

You can make blueprints on paper, textiles, basically anything that you can wet with water. The substances to be used are not very dangerous. The procedures of sensitization and development are simple: for example, the exposure time is neither very short nor very long and you do not need expensive equipment. The disadvantage may be that it always produces a blue/white or (after coloring) gray/white print.

Blueprint – making photosensitive paper – takes two steps:

• making the solutions
• make it photosensitive

Making the solutions

You make the photosensitive layer by first making two solutions and then mixing them in equal parts. From the moment you mix the solutions, the solution is photosensitive. You then apply this photosensitive solution to the substrate. The most suitable is paper that can absorb a lot of water and will not tear, for example watercolour paper, or textiles, preferably cotton or linen.

The two solutions have the following composition:

Solution I

• 10 g Potassium ferricyanide red[32019]
• 100 ml fresh tap water

The Potassium ferricyanide red (T) dissolves quite easily in the water without heating.

Solution II

• 30 g Ammonium iron (III) citrate [32058]
• 100 ml fresh tap water

Ammonium iron (III) citrate dissolves a little less easily, but good stirring is usually sufficient.

Ordinary fresh tap water can be used as water, or, if possible, demineralized water from the supermarket or drug store. The salts to be dissolved can be ordered from De Hekserij. The above recipes are not very precise, it is no problem if a little more or less is solved, feel free to experiment with this. When making textiles photosensitive, a higher concentration is recommended.

Prepare the solutions in a beaker or measuring cup and transfer to bottles for storage. Store both solutions separately in dark glass or PET bottles. No jars with metal lids: iron, tin and steel can have a negative effect on the solutions. Solution II can start to mold, that’s not a disaster, but remove the mold before use.

The solutions are in general green-yellow in colour. The mixture of both can also be dark green or blue. This is due to the formation of Prussian Blue in the solution. This can lead to differences in the end result.

Making it photosensitive

The sensitization should be done in a place with low ultraviolet light, indoors in a not too sunny area is usually fine. Blinds or curtains are closed and every kitchen, every classroom and certainly every darkroom is suitable.

Mix an equal volume of both solutions, for example 10 ml of both. Apply this new solution to the paper or fabric to be photosensitive. You can do this with a sponge, cloth, brush, whatever you want. However, do not use brushes or other items with metal parts, these can adversely affect the process. Then allow the photosensitive material to dry. This should preferably be done in a dark room, for example in the attic, or in a closet. When it is dry it can be used. It can be used wet, but it is more likely to run through and the sensitivity is less. The sensitized paper is yellow-green to blue in colour.

Blueprint – using photosensitive paper

The photosensitive material can now be used for printing. There are several options for this. You can make a photogram: for example, you place leaves, flowers or other things that partially allow light to pass through on the paper and illuminate it. Because thin leaves let through less light than thick ones, a photographic image is created.

Another way is to print from a negative. You can adjust a photo in an editing program to black and white, then invert the colors (so what was white becomes black and vice versa) and print this with a good photo printer on foil or possibly on paper. Good contrast is important! Place the negative thus made on the photosensitive paper and expose it.

The traditional way of reproducing drawings can also be used. Place the drawing on the photosensitive paper and expose. Of course, this works best if the paper is as translucent as possible, for example tracing paper, and if the drawing itself blocks out as much light as possible, for example by using Indian ink. Experience shows that it is also possible with drawing paper and pencil, but the contrast is less and the exposure time is longer.

Light sources

Lighting is easiest with sunlight. Lighted outside, glass windows block a lot of ultraviolet radiation. The exposure time depends on the conditions, in bright sun light, around 1 pm on June 21 the exposure time is short, maybe just a minute. In winter and when it is cloudy, this can be much longer. It also makes a difference whether you use paper or foil as a negative.

Other sources of ultraviolet light are also suitable. An ultraviolet light box with a timer is ideal, but a facial tanner can also do the job. Exposure times should be tried, you can also play with this and underexpose or overexpose.

Once the photosensitive paper has been sufficiently exposed, the image must be fixed. This can be done very simply by rinsing the paper with plenty of water. Preferably do this in a somewhat dark room, for example the kitchen or bathroom with the curtains closed. When the paper no longer gives off a green color, it is fixed and can dry.

The created image may discolour over time, so do not hang it in the bright sun.