In order to cure the ink so that your images will be color-fast when washing, it is necessary to heat treat the image so that the image bonds with the garment.
Once you have printed your image, carefully transfer the image to your preferred heat curing machine. Be sure your print image is facing up.
If you are using a heat press, it is recommended to allow your print image to sit so it prevents the colors from mixing. Depending how much ink is used, you should allow the print image to sit for as low as fifteen seconds to as high as one minute. Once you have allowed your print image to sit and colors to settle, grab your Heat Press Paper and cover the entirety of your print image (Doesn't matter what side of the Heat Press Paper). Make sure the temperature of your heat press is around 330 degrees Fahrenheit and proceed to press down your print image for 90 seconds. Once the allotted time has passed, remove the Heat Press Paper and your image should be heat cured. Instructions are the same when applied to a White, Black, and Colored garment.
If you are using a textile oven or conveyor dryer, please test the temperature of the printed image when it exits the dryer to assure that it has reached 330 F or 165 C.
Also please do a wash test of your first attempts to be sure that the inks have cured properly, and wash ability has been attained.