Urea is used in tie dyeing, or other direct application dyeing. It is generally not used in solid color dyeing. Moisture is an important component of the chemical reaction process with these dyes. Urea helps draw moisture to the chemical reaction, helping the dye penetrate the fabric. Urea also helps large amounts of dye dissolve in small amounts of water. We estimate that 10 pounds will prepare enough solution for about 160-180 shirts.