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Sun printing on cyanotype fabric by blue print technic

The beautiful swirls of patterns and designs on that pretty fabric that found from the fabric store – are nothing but various methods of printing. Textile printing is the sequence of applying color on fabric in particular patterns and designs. It requires much effort to achieve precision and perfection and durable fast colors on the surface of fabrics. Some specialists believe that one-day innovative printing will replace the dyeing process. Sun printing is one of them. It is the easiest but elegant way of permanent printing.

Sun printing

In this type of printing, the fabric is coated with a chemical, liquid photo emulsion that is sensitive to light and then any photograph can be printed on it.

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Figure 1: In sun printing, the fabric is coated with a chemical, liquid photo emulsion that is sensitive to light and then any photograph can be printed on it. Courtesy: Collected

Sun printing is one such technique which is used very frequently. This was a method invented by Sir John Herschel and with this, an impression can be made of most objects on any pretreated fabric. White/light-colored prints are made on blue background. Other than the blue and white combination, it is also found Green with Light Green prints, Green with Orange prints, Blue with Pink prints, Blue with Turquoise prints with the same functionality.

Astronomer John Herschel’s invention of the cyanotype fabric

Sir John Herschel knew that White light is composed of the color spectrum. The trick was to separate the White light and pinpoint specific colors by using the prism. First, separate all but the pure prismatic tint of re-frangibility and then re-analyzing this by media. He experimented with hundreds of variations of chemical formulas, using engravings as source imagery to create negatives on paper. In 1842, Herschel invented the cyanotype.

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Figure 2: Cyanotype fabric. Courtesy: Collected

What is cyanotype process?

The cyanotype process uses light-sensitive iron salts produced by brushing solutions of ferric ammonium citrate and potassium ferricyanide, also known as Prussian blue, which is dried in the dark. Cyanotypes require only water for fixing the image. The cyanotype is the originator of the architect blue-print.

What is a cyanotype fabric?

Cyanotype fabric is a pretreated fabric that allows making white prints on a blue background. It is made of cotton or silk noil and it is treated with some powerful chemicals. Until the Cyano-fabric fabric is exposed to light, it will be pale green but once it is exposed to the sun and it is washed, it turns to a blue color, leaving the print in white.  The fabric is also called blue print Fabric.

Preparation of the fabric as cyanotype fabric

The main advantage of preparing the fabric is that the choice of fiber and weave from delicate, dreamy silk chiffon, or crisp, cool linen through a smooth, tightly woven cotton to a rich, sumptuous velvet any fiber can be chosen. The only natural fiber or fabric that had trouble with is wool.

First need to prepare light-sensitive solution

The two chemicals used are:

  • Ferric Ammonium Citrate, a green powder. It absorbs moisture from the air so it’s kept in an airtight container. It is also a very light powder so it’s best not to have a window open while measuring this out as it can fly everywhere.
  • Potassium Ferricyanide, which is in the form of bright red crystals

The basic recipe is as follows:

  • 15g or 1/2 oz Potassium Ferricyanide plus 30g or 1oz Ferric Ammonium Citrate to 250ml or 8fl oz warm water. Use either metric or imperial measurements.
  • Weigh out the appropriate amount of each chemical, with a dust mask and gloves in place. Then replace the lids on the containers and put them away.

The recipe is mixed and then the fabric is immersed in the solution, soaked for a few minutes, then squeeze out the excess solution.

It is suggested that the treated fabric can be dried in a domestic tumble dryer at the lowest setting. It will take about 20 minutes for a couple of meters of medium weight cotton or heavy silk and 10 minutes for very lightweight silk.

The treated fabric needs to be hung on a plastic clothes line to dry, must in a dark place.

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Figures 3: Leaves, feather, printed designs printed on Cyano-treated fabric. Courtesy: Collected

Storing of cyanotype fabric

It is always sealed in a UV protected bag and it is not exposed to any light till the last minute after everything is ready for printing.

What can you print on the fabric?

Vivid permanent prints of different objects like feathers, flowers, printed drawings and texts, large photographic negatives, wooden molds, everyday objects which will lie flat on the fabric, lace and other open-weave fabrics, computer printed designs anything can be recreated on this specially formulated fabric.

Photos can be printed as a negative on this fabric – if a photo is to be transferred into the fabric with this printing process it is very easy to do; just print it in a clear transparency or acrylic sheet. Use it the same as any other object and a photo negative effect on Cyano-fabric will be found.

Sun printing process

  1. The object is kept close to the Cyanotype fabric and exposed to sunlight, resulting in the beautiful image imprinting on it as a negative printing. The print will be white while the background changes to blue. Different exposures result in different shades in the print.
  2. A very sunny day is chosen for sun printing. If the fabric is wrinkled, press on the wrong side of the fabric with a dry iron.
  3. The fabric flat is kept on a flat surface; better to tape it onto cardboard or something stiff/flat like a styrofoam sheet.
  4. Keep acetate sheet/molds or real object like a leaf to be printed on the fabric.
  5. Keep a piece of plain glass or clear acrylic which will not block sunlight at all- total transparency is needed here on top of the object to make it flat and increase tight fit to the fabric. The glass should make the printing object as close as possible to the fabric. The exposure to the sun is kept for some 10 minutes and more if the sun is not warm enough.
  6. The object is taken out carefully from the fabric then rinsed in clear cold water, before using. A little bit of Hydrogen Peroxide is used in the first rinse to deepen the blue color of the fabric.

Important tips and precautions in using the blueprint fabric

  • The fabric should not be exposed to any light before the printing process. If cutting is needed for this fabric, it will be better to do it in a room with little to no sunlight /any light.
  • One thing that has to be careful when dealing with the Cyanotype fabric is that hands and any object touching the fabric should be dry.
  • Gloves should be used when handling the fabric before it is washed as it may contain allergic chemicals. Preferably should use a mask; if anyone is allergic kind, these precautions are necessary.
  • Do all the preparations before printing inside the house
  • The fabric is coated with the chemicals only on one side and it should be checked before printing.
  • Hand washes the finished fabric for retaining vivid colors.
  • Overexposure and underexposure to the sunlight are both not good for this printing.

With overexposure, the print will not be visible, the whole thing will be dark blue. If underexposed, the print will be a light green shade; not the white you wanted it to be.

Final product

Conclusion

Sun printing has a great practice in Slovakian and European tradition of textile decoration. Blueprint has become a common element of folk textiles and dresses with an exceptional richness of local forms and the tastes of rural inhabitants. So, it can be used for an aesthetic purpose. It produces vibrant designs with vivid colors with permanent printing which can attract buyers to buy it.

If anyone has any feedback or input regarding the published news, please contact: info@textiletoday.com.bd

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