What is the effect of temperature on fiber reactive dyes?
The speed with which the reaction occurs depends strongly upon the temperature
around it. For example, if you mix your Procion MX dye into boiling hot water, much of it will
react before it can contact your fabric, resulting in colors much paler than
you were aiming for; mixing up your dyes in room temperature water is important. In the dye reaction, after you put the dye and soda ash on the fabric, if you leave your dyeing to react at 90°F (35°C), you can rinse everything out after a couple of hours, but if it's 59°F (15°C), even two or three days may not be long enough.
Procion MX type dyes
When dyeing with Procion MX type dye, try to keep the temperature of your dyeing reaction at at least 70°F (20°C); if central heating is impractical, you may find an electric blanket
(over a waterproof sheet) to be the answer.
For Procion MX dyes, the hydrolysis rate - that is, the rate at which
the dye reacts with water, making it unavailable for reacting with
fiber - increases approximately three-fold for every ten degree Celsius rise in temperature - that's the same as a 18°F change. [Reference: Ivanov's Reactive Dyes in Biology, p 13.] So, for storage,
refrigerating the dyes
at 39°F (4° C) instead of keeping them at room
temperature, 75°F (24°C) extends the usability of
the solution to about nine times as long.
Other fiber reactive dyes
When using other fiber reactive dyes, such as Cibacron F (Sabracron F) or Drimarene K fiber reactive dye, you will need to keep the reaction temperature higher, as these other dyes are less reactive and require more heat. Try for a minimum of 80°F (27°C) with these other dyes, or higher. Optimum reaction temperatures for many different lines of fiber reactive dyes are listed with their descriptions near the bottom of the About Fiber Reactive
Ways to increase your reaction temperature
The most common reason for pale colors, when dyeing with fiber reactive dye, is low temperature. If your studio is 70°F (20°C), you must leave your damp, freshly dyed items to react at least overnight; some dyers prefer a full 48 hours, at this temperature. If, even then, you find your colors to be reacting poorly, increase your reaction temperature.
My cousin Tammy was dyeing in an air-conditioned school; she found that taking the dyed items, individually wrapped in plastic bags, outside into the summer heat solved the problem nicely.
A number of artists have found that covering the dyeing on their worktable with plastic, and placing an electric blanket on top of that, works nicely to keep the temperature up.
Placing containers of items that are being dyed into a gas oven that is not turned on (warmed by the pilot light), can work well. Placing them on top of a water heater or refrigerator may also provide the needed warmth.
Others find it simpler to place a space heater in a small room, such as a bathroom, which is less expensive to heat than the entire studio.
A Finnish correspondent found her family sauna to be an ideal location to place her containers of materials being dyed.
Another method of applying heat is to microwave the items being dyed. Obviously, you must not include anything with metal in it, such as snaps, and you must not allow the material to dry, or it will burn. I like to cover the container with plastic wrap and microwave for one or two minutes at a time, watching closely, and pausing the microwave whenever the plastic wrap is billowing upward. Microwaving is so quick that it may be necessary to allow your dyeing to rest for an hour or two at room temperature before heating it, to allow the dye plenty of time to soak into the fiber. Fiber that is exposed only briefly to dyeing will be dyed only on the outermost layers, which will show wear badly; this is called "ring dyeing". Moisture is essential, as any fabric which has dried out will burn in the microwave.
Moisture is essential!
Once the dye has completely dried on the fabric, the reaction between dye and fiber will cease. At least a little moisture must be present. Do not allow your dye reactions to dry out before they have spent sufficient time at reaction temperature! Urea mixed with the dye will aid considerably in moisture retention.