RIT is usually wasteful, as it contains both a cotton dye and a polyester dye. It's only useful if the item is a blended fabric. Otherwise, whichever dye your fabric doesn't take will go down the drain, and some of it also will remain on the fabric and transfer onto other items (like people's butts when they sit on the couch). If it's an all-cotton cover, use Jacquard iDye. It's a lot cheaper and it's the more appropriate dye for this purpose. Fiber-reactive dyes will look even more professional, though they're a bit more expensive and you need to use soda ash and synthropol with them. IDye is a better deal for something heavy like a slipcover, which will require a lot of dye. The iDye can be used in a toploader or frontloader washing machine, and I've never had it stain the washer or anything.
