August 21, 2013

Sun Sensitive Paper Along With Other Methods

By Cara Torres


There are are various printing techniques where sunlight is a critical factor. These processes are called sun printing, which makes use of sun sensitive paper in all of the endeavors. Another common thing they all have in common would be their use of sunlight as a fixative or developing agent.

There are several techniques that can be used for these processes. One such technique is called cyanotype. It is also known as blueprinting and it happens to be the oldest non silver photographic process in existence. This technique involves the exposure of materials that have been treated with solutions of potassium ferricynide and ferric ammonium citrate to the sun, which is a UV source.

Positive and negative images can be achieved by the blocking of UV light from the material that has been sensitized. After being thoroughly rinsed using water, the paper will still retain the image. Once it dries, the parts that were exposed may turn a shade of blue as the rest of the parts will stay more or less the same.

There is another method that utilizes Inkodye, which is considered to be a specialized vat dye type. It posses a particular quality in light sensitivity, which means it can be utilized in the process. What makes this particular element unique is that the colors are developed with sunlight when it comes to Inkodyes, unlike the oxygen developed colors of other vat dyes.

These are dyes that are suspended in leuco form and will appear colorless until the moment comes when they are exposed to the UV . The usage therefore resembles the cyanotype, although they have notable differences in them as well. Primarily, these are used on textiles and will exist in full ranges of colors.

The exposure time will vary between three to fifteen minutes. It would depend on what the desired color is or the level of intensity displayed by the light. After being exposed, the sensitized material must be washed with soap and water so that the dye is removed from the unexposed areas.

Other methods as it pertains to sun printing involve the potassium dichromate utilizing photographic processes. These processes are known to allow negative plates to be created when lithographic printing is used. The gelatine films are to be used by spreading it all over rigid and flat surfaces.

Potassium dichromate in a dilute solution is being used to coat the surface before being dried in conditions with low brightness. The treated gelatine layer is to be secured in tight contact with a translucent positive as it is exposed to sunlight over a period of half an hour. At this point, both the light and the potassium dichromate will tan the gelatine being exposed to the light.

Removing and washing out the untanned gelatine with the use of warm water can allow development for the plate. Once it is dry, on the plate will be the revealed relief print. The surface has the capacity to be inked and then printed should there be a need to produce a mass amount. Sun sensitive paper can be considered just one tool within these various techniques that will require tons of effort.




About the Author:



No comments:

Post a Comment

Popular Posts