Fiber and Mordants Guide
Essential technical information for achieving consistent, colorfast results with natural dyes.
Understanding Fiber Types
Different fibers interact with natural dyes in unique ways. Understanding these differences is crucial for achieving the colors and results you want.
| Fiber Type | Dye Affinity | Best Mordants | Color Intensity | Notes |
|---|---|---|---|---|
| Wool | Excellent | Alum, Iron | High | Absorbs dyes readily, produces vibrant colors |
| Silk | Excellent | Alum, Cream of Tartar | High | Shows subtle color variations beautifully |
| Cotton | Good | Alum + Tannin | Medium-High | Requires tannin pretreatment for best results |
| Linen | Moderate | Alum + Tannin | Medium | Similar to cotton but may require longer dye times |
Mordants and Their Effects
Mordants are substances that help fix dyes to fibers, making colors more permanent and often altering the final shade. Each mordant has specific properties and safety considerations.
| Mordant | Chemical Formula | Typical Ratio | Color Effect | Safety Notes |
|---|---|---|---|---|
| Alum (Potassium Aluminum Sulfate) | KAl(SO₄)₂·12H₂O | 15-20% WOF | Brightens, enhances color | Generally safe, use gloves |
| Iron (Ferrous Sulfate) | FeSO₄·7H₂O | 2-4% WOF | Darkens, grays, shifts to olive/brown | Can weaken fibers, use sparingly |
| Tin (Stannous Chloride) | SnCl₂ | 2-3% WOF | Brightens, intensifies | Toxic, use with extreme caution |
| Copper (Copper Sulfate) | CuSO₄·5H₂O | 2-3% WOF | Shifts to green/teal tones | Toxic, proper disposal required |
| Cream of Tartar | KHC₄H₄O₆ | 5-6% WOF | Softens colors, improves leveling | Safe, often used with alum |
Mordanting Process
The mordanting process prepares your fiber to accept and hold natural dyes. The method varies slightly depending on the fiber type and mordant used.
Step 1: Scouring
Clean your fiber thoroughly to remove oils, dirt, and sizing. For wool, use a gentle soap. For plant fibers, a hot wash with soda ash works well.
Step 2: Mordant Bath
Dissolve the mordant in warm water. The ratio is based on Weight of Fiber (WOF). Heat the bath and add your fiber, maintaining temperature for the required time.
Step 3: Rinsing
After mordanting, rinse the fiber thoroughly in cool water. The fiber is now ready for dyeing. Some dyers prefer to dry mordanted fiber before dyeing.
Safety & Disposal Guide
- Always work in a well-ventilated area when using mordants, especially metal-based ones.
- Wear gloves and protective clothing when handling mordants and dyes.
- Never use mordant solutions for food preparation or storage.
- Dispose of mordant solutions properly according to local regulations. Many can be neutralized before disposal.
- Keep mordants out of reach of children and pets. Store in clearly labeled, secure containers.
- Some mordants (tin, copper) are toxic and require special handling. Research safety data sheets before use.
- For plant-based mordants like tannin, disposal is generally safer, but still follow environmental guidelines.
Tannin Pretreatment for Plant Fibers
Cotton and linen require tannin pretreatment before mordanting with alum. This creates a bridge that helps the mordant bind to the fiber.
| Tannin Source | Ratio (WOF) | Method | Result |
|---|---|---|---|
| Oak Galls | 10-15% | Simmer 1 hour | Strong tannin, good for dark colors |
| Sumac Leaves | 20-30% | Simmer 45 minutes | Moderate tannin, readily available |
| Black Tea | 15-20% | Steep 30 minutes | Convenient, adds slight color |