One of my favourite materials for collaging is torn collagraphs. Collagraphs are prints made from a plate that has various shallow textures attached to it.
Inked, damp paper is rolled through the press and becomes embossed by the plate. Below is a simple print made from the above plate, using just one colour. Because the plant material is not fully dried out the plate will not last long before it starts to crumble. Other plates last many years. Unless it needs to be transparent I usually use hardboard for the plate. After firmly gluing everything into place the whole surface must be coated with shellac varnish to completely seal it.
As well as dried plants, to make the plates fabrics, corrugated cardboard, card, bubble wrap and any other shallow-textured materials can be used, including sand, grit, incised plaster, carborundum, acrylic mediums and sandpapers, providing it will not cut into the press blankets.
The collagraph above was made from a plate with a variety of laces, gauze, hessian, string and other fibres, as well as plastic netting and incised plaster, and has then been machined into. This one was then hand-coloured with acrylic after being put through the press 'blind', i.e. without printing inks.
The one below is from the same plate, but using printing inks to create very different effects.
By wiping some of the inks onto the surface, (relief printing) and pressing some deep into the grooves (intaglio printing) is possible to get one colour against another, as in the top half.) I usually use two main colours and a thin wipe of a third, in this case yellow.
