Dissecting Silkscreen Separations

CMYK colour separations

Accuracy of registration

Accuracy of colour

Consistency of print quality

The idea of layers of colour and experimenting with texture and opacity was interesting so I began using process colours and layering them to reproduce a digital photographic original. The process colours were split four ways, reminiscent of a schizophrenic personality and combined to recreate a four colour process print. Cyan, Yellow, Magenta and Black; Folex or Acetate positives of these four colours (silkscreen printed in this order) were made and then exposed as separations on a silkscreen, registered and printed, one at a time, to recreate a full colour, photographic quality print.

I have been experimenting with halftone dot structures, patterns and extreme colour. On my computer screen, the brightness of each finished piece of artwork was immense and I wanted to try to replicate this vibrancy of colour using the silkscreen process. I thought that the silkscreen method would enable me to reproduce my images on a variety of surfaces, allowing for experimentation with both 2 and 3 dimensions, particularly as it is my intention to work with a variety of fabric samples.

I exported and then printed my CMYK separations from both InDesign (JPEG files) and from Photoshop (PSD files) to compare the quality of the positives from different software programmes. Unfortunately, my first print efforts were unexpected. I forgot to take into account the ‘moiré’ pattern (which was more pronounced when printing positives from Photoshop), where the linear textural composition of the areas of contrast affected the transposition of layered colour considerably. Also, when printing out the series of acetate positives the printer cropped the registration marks from the artwork, causing me to print the Cyan positive as Magenta which altered the colour of the image so it was unrecognisable compared to the original. Therefore, I had my positives reprinted from the original JPEG files by lovely Ben in 2D print. The end result was an experimental education albeit it dull. Printing process colours in order is essential as is printing the correct colour with the correct positive. What a moo!

 

 

The ‘Moiré effect is a visual perception that occurs when viewing a set of lines or dots that is superimposed on another set of lines or dots, where the sets differ in relative size, angle, or spacing. The moiré effect can be seen when looking through ordinary window screens at another screen or background. It can also be generated by a photographic or electronic reproduction, either deliberately or accidentally.

Moiré effect can produce interesting and beautiful geometric patterns. However, the phenomenon degrades the quality and resolution of graphic images. Problems occur when a screened image, such as is found in a newspaper, is directly photographed and then the photograph is reprinted in screened format. It can also occur when the image from a computer display is reproduced by photographic means and then rendered in a screened or dot-matrix format. The fine matrix of dots in the original image almost invariably conflicts with the matrix of dots in the reproduction. This generates a characteristic criss-cross pattern on the reproduced image.”

http://whatis.techtarget.com/definition/moire-effect

Accuracy of registration is the key to my success here and in order to replicate each print with precision I had to use a ‘flip-sheet’. Therefore in the future if I choose to produce more silkscreen prints in this way, in order to be successful I need to check for ‘Moire’, accurately register my print and just bloody concentrate.

The final screenprints were interesting but lacked the colour intensity of the

‘on-screen’ originals and I was disappointed. The designs worked better on fabric when printed digitally. Hand rendered textile prints using a combination of a silkscreen printed keyline and acrylic paint directly onto fabric and textured paper has given me a more intense colour and a much more accurate and satisfying end result.  The figurative patterns were rather chaotic but the more chaotic and complex, the more I liked it.