Common Additives and Their Colors:
1. Cobalt Oxide - Color: Deep blue.
Health Concerns: Generally safe when used in finished glass, but cobalt dust is toxic if inhaled.
2. Chromium Oxide - Color: Green (ranging from light to deep emerald).
Health Concerns: Can be toxic; chromium compounds (especially hexavalent chromium) are carcinogenic if inhaled.
3. Copper Oxide - Color: Turquoise, green, or red (in a reducing environment).
Health Concerns: Generally safe in finished glass, but copper dust and fumes can be harmful if inhaled.
4. Iron Oxide - Color: Greens, browns, blues.
Health Concerns: Considered relatively safe; iron oxides are not highly toxic.
5. Manganese Dioxide - Color: Purple or amethyst.
Health Concerns: Potentially harmful if inhaled in dust form; can cause neurological effects (manganism).
6. Gold Chloride - Color: Ruby red or pink.
Health Concerns: Safe in glass; expensive but not toxic.
7. Sulfur, Carbon, and Iron Compounds - Color: Amber, brown, black.
Health Concerns: Generally safe in finished glass.
8. Selenium Compounds - Color: Pink, red, orange.
Health Concerns: Selenium compounds can be toxic in raw form but are safe when incorporated into glass.
9. Titanium Oxide - Color: Milky white or opalescent.
Health Concerns: Safe in finished glass.
10. Nickel Oxide - Color: Purples, browns, blues.
Health Concerns: Can be harmful if inhaled; considered a potential carcinogen.
11. Uranium Oxide - Color: Bright yellow, green; glows under UV light.
Health Concerns: Uranium glass is slightly radioactive; generally considered safe to handle but not for food use.
12. Silver Nitrate or Silver Compounds - Color: Yellow, orange, red.
Health Concerns: Safe in finished glass but raw silver compounds can be toxic.
13. Lead Oxide - Color: Enhances clarity and adds brilliance; used in crystal glass.
Health Concerns: Lead is highly toxic. Leaded glass can leach lead, especially when in contact with acidic substances or if not properly sealed. It's not recommended for food or drink containers.
