| 1 | Wool — pale and medium shades | Leveling acid dyes | About 4–6 | Gradual heating, commonly to around 95–100°C | Good migration and levelness; wet fastness varies by dye and shade. |
| 2 | Wool — medium to deep shades | Milling acid dyes | About 4–5 | Near-boil dyeing, with controlled heating and cooling | Often selected when better wet fastness is needed than conventional leveling dyes provide. |
| 3 | Wool — high wet-fastness requirements | Supermilling acid dyes | About 4–5 | Near-boil dyeing; follow the dye’s recommended hold time | Assess shade build-up, levelness, and fastness on the actual wool construction. |
| 4 | Silk — bright shades and level dyeing | Leveling acid dyes | About 4–5 | Typically 80–95°C; use a gradual temperature rise | Avoid unnecessarily harsh, prolonged boiling that may affect the silk’s handle and appearance. |
| 5 | Silk — improved fastness requirements | Selected metal-complex acid dyes | Usually about 4–6, subject to product guidance | Typically 90–98°C with controlled circulation | Check the specific dye’s suitability for silk, shade range, and required fastness tests. |
| 6 | Nylon — pale and medium shades | Leveling acid dyes | About 5–6 | Gradual heating, commonly to around 95–100°C | A controlled pH and dye addition help reduce rapid, uneven uptake. |
| 7 | Nylon — deep shades or faster exhaustion | Selected acid dyes at lower pH | About 3–4, where the dye and nylon grade permit | Near-boil dyeing with careful pH adjustment and dosing | Lower pH can increase exhaustion and may make levelness control more demanding. |
| 8 | Nylon — fastness-focused shades | Selected 1:2 metal-complex acid dyes | Commonly about 4–6, depending on the product | Typically near-boil dyeing; use the supplier’s technical instructions | Verify shade reproducibility and relevant wash, perspiration, and light fastness. |
| 9 | Wool / nylon blends — matched shades | Compatible acid dye combinations | Often about 4–5; confirm for the blend and dye set | Near-boil dyeing with a controlled heating profile | Test component-wise staining and shade balance because wool and nylon may exhaust differently. |
| 10 | Laboratory screening — wool, silk, or nylon | Candidate acid dye range and auxiliaries | Screen within pH 2–6 only as appropriate for the fiber and product | Record liquor ratio, heating rate, peak temperature, and hold time | Compare shade, levelness, exhaustion, and fastness using the intended substrate and process. |