Submition by Ragnar

Submitted by Ragnar

From RICHARD GIORNI PORCELAIN SITE.

The Italian porcelain manufacturer is seeking a buyer. 

This description of decal technique is interesting.

·       Decalcomania

When it comes to porcelain decoration, the application of decalcomanie (transfers) is one of the most commonly-used techniques. Using a pattern from the factory archives, or a picture or logo designed by a private customer,the product development workshop can produce a slide containing a black background of the colour. A polyester support is then prepared, onto which the slide is glued, until it covers all the available space. The next stage is preparation of the screen printing supports, the metal frames between which a dense polyester mesh or “silk” is stretched. This is covered by a fine layer of photo-sensitive gel. Each support is lain onto a mesh, and placed under a UV lamp, which hardens the gel only in those areas affected by the light. On the areas covered by the slide, the gel is removed with water, cleaning the weave of the fabric thus enabling colour transfer. Printing requires a special type of paper, on which a thin layer of dextrin (a natural water-soluble adhesive) has been applied. A screen printing machine is used, with a sliding rigid rubber spatula that spreads a dense blend of paint and oil onto the mesh. This mixture can penetrate the clear areas of the weave and deposit on the paper. Once the print process is complete, all the colour papers are carefully checked. Small holes can appear in the silk, due to wear and tear or dust, so that the colour passes through during printing. This creates small imperfections on each sheet of printed paper. These blemishes are removed or scratched off using a scraper or felt tip, while papers with larger irregularities are marked with a pencil before being discarded. Before the transfers (decals) are applied, the printed sheets are covered with a layer of collodium, a film of resin dissolved in special solvents. When the thinners have evaporated, the collodium forms a plastic film, through which the decorations can be smoothed out with no risk of tearing or pulling. This process is also suitable for ribbed, hollow or convex shapes. Before application, each design must be removed from the screen printing paper. The operator will immerse them for a few seconds in a tub of demineralised water, so that the dextrin dissolves, releasing the collodium surrounding the colour, which slides easily onto the paper. The worker will then take the decal and lay it onto the porcelain, taking great care: any water or air bubbles which could cause tearing or creasing during the firing process must be eliminated by pressing gently with the fingers and a soft rubber spatula.