Gold Toner (GP-1)

Gold Toner (GP-1) is Kodak's gold-thiocyanate toner formula — provides archival permanence enhancement comparable to selenium toning, plus a distinctive cool-blue color shift on most B&W silver-gelatin papers. Gold toning was Kodak's original archival recommendation in the early 20th century, predating the rise of selenium toning; GP-1 remains in occasional use today for the specific cool-blue aesthetic and as an archival alternative when selenium isn't available.

Key features

• Gold chloride + sodium thiocyanate + sodium chloride + sodium acetate chemistry
• Cool-blue color shift — distinctive on chlorobromide and bromide papers
• Archival enhancement comparable to selenium (both are silver → noble-metal-conversion mechanisms)
• Significantly more expensive than KRST due to gold chloride cost
• Single-bath process (no separate bleach step)

Workflow

1. Print → develop → stop → fix → wash thoroughly (HCA recommended)
2. Toning bath: 5-15 min in GP-1 working solution at 20°C; watch for cool-blue shift in highlights first
3. Final wash: 30+ min running water for archival residual-thiosulfate levels

Practical notes

• Choose GP-1 over KRST when you want the cool-blue aesthetic with archival benefit
• Choose KRST when archival benefit is the priority and you want minimum visual shift
• Gold chloride costs $200+ per gram — GP-1 is the most expensive toner in routine use
• Working bath capacity ~20-30 8x10 prints per liter
• Stock keeps 6+ months sealed
• Compatible with most papers — but test on a sacrificial print first as some papers respond more dramatically than others
• PPE: nitrile gloves; gold chloride is moderately toxic

Related recipes

• [[recipe-krst|Kodak Rapid Selenium Toner]] — alternative archival toner with subtle warm shift
• [[recipe-sepia-toner|Sepia Toner]] — dramatic warm alternative; less archival benefit
• [[recipe-blue-toner-iron|Blue Toner (Iron)]] — non-archival blue alternative for color only