In the dyeing of wool/rayon blends using reactive dyes, the rayon must be dyed first.  If not, the majority of the dye tends to exhaust on the wool at the elevated boiling temperature, and leaves little dye for the dyeing of rayon.  What happens is the rayon never fully reaches the depth of shade of the wool.  The procedure following is used for a deep blue black on 80% wool / 20% rayon blend.

1. When rayon is present in a fiber or fabric blend, it is important not to exceed a pH of 9 during any processing procedure as it may lead to saponification of the rayon fiber.
2. Prepare goods as necessary.
3. First dye the rayon, setting the bath at 110°F(43°C) containing:
   • 13 oz/gal(100g/L)          Common or Glauber’s Salt
   • 1.0 % owg                     Orconol CHSA Conc™
4. Circulate for 10 minutes and add X % owg Orco Reactive Wool Black WM Conc™ properly prepared.
5. Slowly raise temperature to 140°F(60°C).
6. After 15 minutes, add soda ash to a pH of 9.
7. Run for an additional 45 minutes.
8. Reduce temperature to 120°F(49°C) and adjust pH to 3.8 using formic acid for the dyeing of the wool component.
9. Raise temperature to the boil and dye for 60 minutes.
10. Cool to 140°F(60°C) and rinse.
11. Soap at the boil using 0.25 % owg Orcopon KP™ for 10 minutes.
12. Hot rinse then cold rinse.

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