Recommendations for Fabric Dye?

What dyes work best actually depends on the fiber.

It would help to know what fibers you are planning on using. Wool, silk, angora, alpaca, are called protein fibers and can be dyed with any dye. My favorite is natural dyes, but food coloring works well with vinegar. Can find lots of info on web. Never boil. These dyes exhaust (take up the color in the water) well. Food coloring, also found in kool-aid used a lot lately by women who don't want to have heavy metal dyes around children. I think these dyes are kind of a bridge dye between harmful and not so harmful.

I honestly don't know if you can use food dyes on cellulose because I deal mainly in wool, silk and angora. But I would assume they work some because kool aid stains so badly. I use food coloring paste if I use this kind at all, and there are nice colors and easy to do. The paste dyes are very intense and little is needed at all to get an intense dye. I used a cheap brand cherry kool aid to overdye an old wool scarf an intense red. Took 6 packs (10 cents each on sale)
and 1 cup vinegar in a gallon of water. Scarf probably weighed 6-8 ounces. These dyes "strike", suck into fiber at about 180 degrees, so just below simmer. Always soak fiber for about 1/2 hour in hot water,before adding to hot water.Wool should be transferred from same temp to same temp or will shrink

Rit, or all purpose dyes works on cellulose as well: that would be cotton, linen, hemp, rayon, and I believe even nylon which is a synthetic. Rayon is a synthetic made from cellulose. The all purpose, also called union dyes, leave leftover dye color usually because the dyes are a combination meant to dye both kinds of fiber and the fibers will 'take up' their own type and leave the rest of the dye.

There are other dyes called acid dyes which lots of women use, which are quite light fast and very intense, but I've never used them. Procion I believe is one brand. There are lots of books in the textile section of the library on dyeing, both natural and synthetic.

I love natural dyeing, but it takes some effort to collect the supplies. Alum is the most common mordant and if you are in a larger town you can find alum crystals (used for making crisp pickled vegetables) in your local large oriental foods market quite inexpensively. Can be found on ebay as well.

I recommend to anyone interested read through
aurorasilk.com. Cheryl has great tutorials and info on natural dyes and a color chart of 120 colors of what is possible with natural dyes. I also recommend
lenealve.blogspot.com, a woman's knitting/dyeing
blog from Finland, and I think it's riihivilla.com
also from Finland (google it first) for a lovely site on natural dyeing..both sites in English.

Ashford (google) makes spinning wheels and sells dyes and you can read up on that too.

Synthetic dyes contain heavy metals. These are a danger to our environment and caution is required as far as leftovers, and you can't use your cookware.You have to use separate pots etc. Even for natural dyes, which also use metals as mordants: alum, copper, tin, iron. So those things have to be kept up. Best do do dying when children aren't at home, until you are sure of your management. However mordant solutions can be stored and used until completely exhausted and then one is mostly discarding water which can be poured around trees. Unfortunately for synthetics most goes into our water supply so that should be exhausted (dye something with left over until water is as clear as possible, meaning the dyes are in the cloth or fiber and not going into water system or ground).

It's a wonderful adventure, dyeing, and one can also enjoy gathering dye stuffs if you get into natural dyeing, but it is not always predictable. It's so cool though.

One can start gathering many pieces of dyeing equipment at garage and estate sales. Enamel or stainless steel pots. Not aluminum. A scale is good because weight of dried fiber to weight of dye is good for getting consistent colors. Masks as for painting are good because dye is powdery, unless one gets liquid dye (Rit). Many people who really get into dyeing on a larger scale make up percent solutions and keep in jars or bottles (store away from children) and thereafter use liquid measurements. So several sets of measuring spoons and cups is good.

For fun, one can use some things around the house as well. Tumeric makes a lovely bright yellow on just about anything. Can be bought in packets in an Indian or Oriental market for under a dollar. One tablespoon in cup of hot water and then filtered through a coffee filter, put in a pot, with other water added would dye 4 ounces a nice light yellow. Heat but don't boil. Rinse well, wash separately thereafter.

It will fade some, but can be redyed easily.

For all color workers, whether with dye or inks, etc.
If you keep a supply around of bright yellow, strong cerulean type blue, and a magenta, you can mix almost any color under the rainbow.