Tin mordant, also known as stannous chloride, is a chemical compound with the formula SnCl2. It is a white crystalline solid that is commonly used as a reducing agent and as a mordant in dyeing and printing textiles.
 
As a mordant, tin mordant is used to improve the colorfastness and brightness of dyes on fabrics. It can be used with a variety of natural dyes, including madder, weld, and cochineal, to create vibrant and long-lasting colors. Tin is particularly effective for deep, true reds with cochineal. 
Tin mordant is particularly useful for dyeing silk, wool, and other protein-based fibers.
 
To use tin mordant as a mordant:
Dissolve the crystals in hot water (off the boil)to create a solution. The concentration of the solution will depend on the type of fabric and dye being used.
As a general guideline, a WOF of 1-2% for tin mordant is commonly recommended for protein fibers such as silk or wool. This means that for every 100 grams of fabric, 1-2 grams of tin mordant should be used. 
When mordanting wool, I recommend adding 6% of Cream of Tartar to the mordant solution as an acidic buffer.
Next, immerse the fabric in the hot solution for a period of time, typically between 30 minutes to an hour. After the fabric has been mordanted, it should be rinsed thoroughly to remove any excess tin mordant.
 
To minimize the risks associated with tin, it is important to handle it with care and to follow proper safety procedures. This may include wearing protective clothing and respiratory equipment, working in a well-ventilated area, and avoiding ingestion or prolonged skin contact.
CAS No 10025-69-1