OrcoChrome™ mordant dyes offer the best washfastness and coverage properties on Spandex^®.  However,   the process requires sodium bichromate which leaves chrome in the dyebath.  It is highly recommended that the local municipalities are contacted before using this procedure to confirm that the resulting chrome content in the effluent will be within acceptable limitations.  In any procedure involving Spandex^® the temperature should not exceed 200°F(93°C) as it may degrade the integrity of the fiber.

Because there is a small selection of mordant dyes that are applicable to Spandex^®, this procedure is generally limited to blacks.  The recommended product for this is OrcoChrome™ Black T 160%.

1. Prepare goods as necessary.
2. In a bath at 120°F(49°C) add:
   • 0.5 % owg     Anionic Wetting Agent
   • 2.0 % owg     Acetic Acid
3. Circulate for 15 minutes.
4. Add required amount of OrcoChrome™ mordant dyes properly prepared
5. Slowly raise the temperature to 190-195°F(88-91°C), and add 2-4 % Formic Acid depending on the amount of exhaustion obtained, and run for one hour.
6. Drop bath and refill.
7. With temperature at 120°F(49°C) add:
   • 1-3 % owg     Sodium Bichromate
   • 4-6 % owg     Formic Acid(depending on depth of shade)
8. Slowly raise temperature to 195°F(91°C) and run for one hour.
9. Overflow rinse until clear and drop bath.
10. Goods may have to be after-scoured for heavy shades to remove any unfixed dye.

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