Recipes without substances that are considered harmful to aquatic life such as:

• Copper / Copper alloys 
  
• Zinc / Zinc alloys 
  
• Recipes without carcinogenic substances like antimony trisulfide (Sb2O3) 
  
• Free of critical curing and processing aids 
  
• Free of fluorides or halogenides 
  
• Free of lead, asbestos, chrome, crystalline silica