Process for producing thin transparent gold coatings

Process of forming a blue colored deposit of gold on a substrate, said deposit having a transmittance of at least about 40 percent of the incident visible light and less than about 30 percent of the incident infrared energy, said process comprising:

• selecting a substantially transparent substrate;
• cleaning a surface of said substrate to produce a clean surface, said surface being cleaned sufficiently to prevent water from beading on said clean surface;
• tribolically applying a solid phase sensitizing agent to said clean surface to produce a sensitized surface;
• preparing a reducing solution of a reducing agent;
• preparing a gold ion solution containing from about 0.1 to 1.0 weight percent gold ion;
• mixing said gold ion solution with a stoichiometric excess of said reducing solution to form a reactant mixture and substantially simultaneously with said mixing, applying said reactant mixture to said clean surface;
• allowing said reactant mixture to react whereby a blue colored gold deposit is formed on said clean surface;
• discontinuing allowing said reactant mixture to react before said blue colored gold deposit reaches a thickness of about 300 Angstroms.