Urea In Tie Dyeing
Every tie dyer has their own opinion about urea. Some tie dyers never use it and others, like myself, use it regularly. If you are wondering, urea is only used in liquid dyeing. I don’t use it when I ice dye or for hot water irrigation.
Let’s start by finding out what urea is. Just like the name suggests - it is a chemical that can be found in urine, but the kind that we use for tie dye is made from natural gas. (Whew - that’s a relief!) You may also recognize urea as a fertilizer.
I purchase mine from Dharma Trading Company: https://www.dharmatrading.com/chemicals/urea.htm
So, why do we use urea for tie dye? There are a couple of reasons for using urea. The first is because it is a humectant. That is a fancy way of saying that it will help preserve moisture. Once liquid dye is applied to a shirt, the shirt needs to stay moist until it has had plenty of time to process. If the shirt dries out - the dye will quit reacting with the fabric and the color won’t be as bright and vibrant as possible. Therefore, you want to keep the fabric damp to keep the dye reacting.
If you live in an area that gets really hot, urea might be helpful because of the humectant properties. I like to process my shirts outside during the summer, and even though I place them in plastic containers that are covered - it is nice to know that the urea will help keep them from drying out too.
The second reason for using urea, is that it helps to dissolve and get the powdered dye into solution. I’m sure if you’ve been dyeing for awhile you’ve noticed that some colors can be tough to get to dissolve (like yellow that just seems to want to float around on top of the water). Urea will help with that. It will also help when you are trying to mix darker dye colors (the really concentrated ones) that require a lot of dye powder. Getting the dye well dissolved helps to eliminate some of the speckling that can occur on tie dye shirts.
According to Dharma Trading Company’s urea instructions - you should use 1 Tablespoon of urea per 1 cup of warm water. If you follow the link above for the urea - there are instructions on how to properly use it in the description.
If the dye that I am mixing is not difficult to get into solution, or if it is not super concentrated (where it requires 8 teaspoons of dye per 1 cup of water), I usually add the dry urea into my mixing container before adding the dye powder and water. Then I mix the dye, urea and water together at the same time. If it is a difficult color to mix or a concentrated dye, I will follow the suggested instructions from the Dharma website that I referred to above.
I like to store my urea in a container that has a tight fitting lid. This will keep any moisture from getting in the container. I purchased the plastic container shown in the photo above from the Dollar Store.