Precious metal preparation
Precious metal preparations are paints containing precious metals that represent substances assigned to paints or varnishes. The type of precious metal preparation is differentiated according to its optical properties. Shiny surfaces are achieved with bright precious metal preparations, semi-matt to matt surfaces with silk-matt or polishing preparations. The most elaborate and noble of all decorations are achieved with powder gold and powder white gold decorations.
The decoration with precious metal preparations most commonly used in industry is that with bright precious metal preparations. The products are characterized by the fact that they do not develop their coloring pigments until they are fired onto silicate substrates . These result from chemical reactions of the organometallic compounds contained in the corresponding alloys . Silver-containing preparations can be used to achieve light yellow shades, and platinum and palladium-containing products to achieve white gold shades.
Bright precious metal preparations are composed of the following components:
- Gold , silver , palladium and platinum (organically bound)
- Binder system (natural and synthetic resins )
- solvent
- Adhesion promoter (organometallic compounds and complexes of metals , e.g. silicon , rhodium , vanadium )
- Auxiliaries ( thixotropic agents , dyes, surface and leveling additives )
As already mentioned, the actual color only develops during the burn-in. The baking temperature depends on the substrate and is between 480 ° C and 1180 ° C. Various methods are established for applying the products. In addition to various screen printing processes , spray processes, pad printing , stamp printing and hand painting are used.