Friday, 1 March 2013

What is Sunprinting?

Greetings all, sorry it has been so long since I wrote something here.  Have been a little bsy of late.  For those with an interest in art photography, this is a little bit of research I have undertaken.

At a recent exhibition one of the entrants  exhibited some beautifully detailed art described as “Sun Prints.”  As I admired them I wondered to myself, “What exactly is an art sun print?” I decided to do some research on the matter and I have probably only touched on the basics about this process, and I may not have everything correct, but this is what I found out about differing types of sun printing.  

Inkodye - Sun Printing On Fabric Using Light Oxidized Fabric Vat Dyes:  In this process fabric is painted with one or more dyes, which are in a chemical colourless form, and which can be concentrated or diluted as required.  Opaque objects may then be placed on top of the dyed surface prior to placing it in the sun.   The area underneath each object remains hidden from the sun, and the  remainder of the dyed area develops the colours after about 15 minutes exposure to sunlight.  Instead of oxygen, UV light is used to cause the complex chemical reactions to occur which change the chemicals, making the fabric permanently coloured.  In those areas that were not exposed, no reactions occur so when the dye is washed away the fabric remains unchanged.  Changing the opacity of the objects placed on the fabric also results in subtle colour changes if a small amount of UV light is able to pass through them to react with the dye.   

Traditional Cyanotype - Blue Printing:    Sun printing can take a number of forms, but what they all have in common is that they use the sun’s  UV light as the agent to develop the print.  Images are formed and the degree of light or dark will depend upon how much UV light reaches the treated surface.   A very old form of sun printing is a method called “blue printing” or “cyanotype printing”, which can be used to create interesting works of art and was also used as an early form of photography and is used for making architectural blueprints.  Generally, the chosen surface is treated with a solution containing potassium ferricyanide and  ferric ammonium citrate, then items are placed upon it to form the desired images and it is exposed to the sun and left to dry. This causes a chemical reduction reaction to occur involving the transfer of iron electrons and (from the latin)   “a blue compound of iron”  ferricferrocyanide is formed, which is one of a number of Prussian Blue pigments.   The amount of light, the concentration of the solutions and the opacity of the items used will all control the colour tones that result.    Photographs are blue and white instead of black and white.  The colour can be either intensified or reduced or actually changed if other chemical reagents are added to the solution, some of which are rather interesting e.g. oolong tea, wine and cat urine (you just have to wonder how that last additive was discovered?!).  
Easy Printing From A Photographic Negative Using Sun Printing Paper:  If you don’t wish to mess around with nasty chemicals, this looks like a really fun way to make interesting sun prints using old photographic negatives and special light sensitive watercolour sun printing paper or solar photographic paper.  The special papers can be obtained from photographic suppliers and even I found examples of this paper at Freestyle.

According to the instructions you choose your negative(s), or pieces of negatives and place them on your sun printing paper in any design you want.  Most suppliers recommend using negatives which have good colour contrast with well defined light and dark areas.  Then you simply place a sheet of glass (not UV protective glass) on top and move it into the sun for 5-15 minutes if it is a bright day, or 30 minutes or more if it is overcast.  Once the paper has been exposed sufficiently simply rinse it under running water until the run off water turns clear.  Dry it flat.  

Lithographic Sun Printing:  A negative printing plate for lithographic printing is carefully prepared using gelatine and the oxidizing agent potassium dichromate.  In a dark room a coating of gelatine is applied to the printing plate and dried.  After this a diluted potassium dichromate solution is applied and dried.  The printing plate is then removed from the dark room and after 30 minutes exposure to  bright sunlight  the gelatine exposed to the light is tanned.  The untanned gelatine is then removed by washing it away, leaving a relief print behind.  This can then be inked and hand rolled and pressed to produce prints.

Setacolour:  From what I can find out, and I may be incorrect, the Setacolour type light sensitive fabric paints are a different process to those mentioned above.  With Setacolour, which is a paint not a dye, the paint already has the colour and it is set in the fabric by the heat from the Sun’s Infa Red radiation.  The heat dries the paint faster in the areas exposed to the sun.  Those areas covered by the objects placed on the fabric remain wet longer. Infra Red heat causes the paint to be drawn away from under the objects towards the faster drying areas, concentrating the colour in those areas. The fabric requires additional heat (ironing) to make it permanent.  

I can’t wait to try some of these techniques in future – I have just discovered a whole new source of creative activity that I never knew existed.  If anyone tries any of these please send us some photos.  

Photo source

Public Domain photo of a photogram of Algae, made by Anna Atkins as part of her 1843 book, Photographs of British Algae: Cyanotype Impressions, the first book composed entirely of photographic images. "Courtesy of The New York Public Library"


Photogram created by slices of lemon on colour photographic paper.  Photo courtesy of  Cormaggio This file is licensed under the Creative Commons Attribution-Share Alike1.0 Generic license.

Well that is it for now.  All my art and craft activities are on hold until after I have moved to Canberra.  Everything is packed away and I just have a few tubes of watercolour paint to play with for the moment.  

Cheers all, until next time and happy creating.