Andrea Canducci shows us how to make prints using a printing system from the electronics world.
This photoengraving on copper is a printing system that comes from the electronics world where is used to make homemade printed circuits.
The photoengraving is a method of photo impression on a copper base of a sign (or in this case a picture).
These plate are a sandwich of materials composed of a layer of copper on a plastic support coated with a special paint “photoresist” (protected by a film). These copper strips can be homemade or purchased in special shops of micro-electronics components.
To achieve the right exposure you need to use a source of UV light that it can be obtained simply by exposing our plate on a sunny day or using a special UV lamp. Exposure times vary with the light source and intensity (range from 10-20 minutes with a lamp and one day a week outside).
The acids that we will need for develop and fix the image are respectively caustic soda (NaOH) and ferric chloride (FeCl36H2O).
Be very careful with these acids because they are very corrosive and they could damaging yourself and the environment (so it is recommended the use of protection and an appropriate disposal).
1Making your “negative”
The chosen image will be printed on a transparency sheet with any ink-jet printer. Taking care to adjust the contrast of the image in a strong way. With this system there are no half-tones!
The amount of soda it will be needed for the development bath is really small, about 10cl of soda (on 40 volumes) for 3.5 liters of water. The ferric chloride instead is usually sold together with the indications of dilutions in water (about 250g per a liter of water).
The procedure is similar to the creation of contact printing but can be done even in the presence of a dim light. Takes off the protective film of the photosensible paint and apply our positive print under the UV lamp. Stops the whole with a glass.
Once that our plate is exposed. put it in soaking with caustic soda until the paint not exposed is washed away and your image will appear clear. Rinse with water and soak it in the ferric chloride, wait until the copper in excess will not be completely washed out from the plastic support. It is advisable to heat the ferric chloride to accelerate the timing of that process.
If the engrave obtained is a bit weak, you can repeat the process of developing and fixing.
6Rinse and polish
Rinse in water the photogravure and then clean it with a paint thinner to remove the remaining unexposed paint and give to the surface its natural aspect shiny copper-gold.