Puretch processing guide written by Jennifer Page, Cape Fear Press. All rights reserved ©2001-2015.

TO BE TRANSLATED INTO GERMAN

This page shows the enlarged details of an exposed plate (in three different ways), laminated with Puretch.

 

FINEST. Greyscale Inkjet Sample

Above is a 1/4x1/4 inch plate sample exposed with an inkjet transparency printed at 1440 dpi on Posjet inkjet film with an Epson 740 printer. The original image was a 600 dpi light gray swatch, grayscale image. The photo at the right shows the etched plate the sample was taken from. The area of the plate (roofing copper) that was tested was polished with a metal polish then degreased with Ajax. These are the smallest dots the Epson740 outputs; 6 picoliter dots to be exact. A 6 picoliter dot is 23/1000 mm. in diameter. The dots are actually grouped in pairs to create the illusion of smooth tones. The main difference in this sample and the "Finer" sample is this is a grayscale image and it was not converted to a bitmap before printing. It was printed just like you would print a high resolution photo on glossy inkjet photo paper. You will need to reduce the output by adjusting the curves before printing to open up the dots and conserve ink. The grain of the etched dots in the plate are barely discernable and the dots on the transparency are only visible with a loupe.

FINER . Bitmap Inkjet Sample

Above is a 1/4x1/4 inch plate sample exposed with an inkjet transparency printed at 1440 dpi on Posjet film with an Epson740 printer. The original image is a light gray swatch, converted to a 1400 dpi bitmap. The photo at the right shows the etched plate the sample was taken from. The area of the plate that was tested was polished with a metal polish then degreased with Ajax. This photo proves that a plate doesn't need to be excessively abraded for adhesion. The inkjet samples demonstrate how you can output small size (8.5x11") quality positives without expensive equipment and processing.

FINE Imageset Bitmap Sample

This sample at the left was exposed with a 400 dpi bitmap output on an imageset positive. In the optimum industrial set-up, the makers of Puretch claim it will produce lines and spaces down to 1/1000". That's more than enough resolution for conventional photo etching. Puretch resist does what the toxic liquid resists did but better because the application thickness is always consistent. None of these results are possible with the thicker films available.