The first and second things I ever dyed turned out the best, I believe.
First was a pair bright blue swim shorts. They were 100% nylon so I used dye specifically for synthetic fabric.
These swim shorts used to be about the color of that blue kayak before I dyed them.
The instructions call for heat.
Basically you cook the water, dye, and fabric in a pot you intend to never use for food again. I bought a large aluminum pot at the thrift store just for this purpose. I used black dye and at first the shorts looked pretty black. After dying you have to wash the fabric, sometimes several times, to get out any dye that is going to leach out. The shorts ended up a very nice navy blue. Even the plastic button took the dye. I'm not going to lie, this dying process is smelly and can be messy, but it was totally worth it. I've been using those swim shorts a couple of years now and they've held up beautifully.
The second thing I dyed was a sweater.
Our family dressed up as the Scooby Doo gang for Halloween a couple of years ago. I was Velma. I hit the thrift store to look for a big turtleneck sweater. Finding one that was orange was never going to happen, but I did find a white cotton one.
Using regular, orange fabric dye, I dyed the sweater in the washing machine. It was so easy! The color was perfect.
The next two projects are tied so far for um, second place I guess. Our new house has an HE washing machine and only fills up enough to cover whatever is inside-just barely. I don't think dying fabric in this washing machine would work well, so I haven't tried it.
The thing I wanted to dye was also very, very large (it takes two separate loads to wash). So I gave dying in the bathtub a try. I bought a slipcover for an L-shaped Ikea Ektorp couch from the as-is department.
It was brand new in the package and only $10, but it was pink.
I figured I'd try dying it before we committed to actually buying the couch. I used regular brown dye and had to dye the cushion covers separate from the frame cover- it was A LOT of fabric!
It's not really recommended to dye stuff in your bathtub because it can stain.
We had a tub already in kind of bad shape (it needs to be re-glazed or something) so I wasn't too worried. The first "batch" didn't even stain the tub.
The second did a little bit (may have had something to do with not having time to clean up as thoroughly afterward that time). The dye job worked well enough. The cover is brown, there are a few splotchy areas (it's hard to move that much fabric around freely and that leads to a bit of a tie-dye effect). The fabric close to the welts still looks a little pink if you look really closely. But overall it looks fine. The biggest problem I had was that I followed the directions on the fabric tags and used hot water when I washed it afterwards. It caused the cotton fabric to shrink a little bit. I did not put it in the dryer.
We did end up buying the couch to put the slipcover on and are pretty happy with it.
Here's a pic of the couch on Christmas morning.
My latest project was dying my pink diaper holder/changing pad black.
It is nylon, so I had to use the pot method and special dye again. The fabric is somewhat rigid and the pot was a little small for it to move around completely freely.
I did my best though to move it frequently.
I think I might have "over cooked" it a bit. The fabric got a bit crunchy wrinkled. It was very dark after dying and has gotten a bit more gray with repeated washings (dye kept coming off on my hands from it so I had to rewash a couple times) and it's a little splotchy too but not bad.
I realized later that there were little black spots all around the stove after this project. I guess some dye got carried in the steam. A magic eraser took them all off though.
My worst dye project was a dye fail. Before we moved, I tried to dye our polyester bed skirt.
It was way too big for the pot, but I tried to just do the visible edges. It didn't work. It looked tie dyed and the green fabric+brown dye turned a very ugly color. That one ended up in the trash and I bought a new bed skirt which I was prepared to do anyway.
Those have been my experiences with fabric dye. It can be risky, but it can also be awesome. In the future, I may try dying some of my stained maternity shirts to see if they can be saved. I've also seen people dye old jeans darker and people who have to wear black clothes for work dye them to keep them from looking faded. I've bought dye at Michaels and Joanns. Joanns is where I've found the nylon/polyester dye and they usually have a larger selection of dye there as well.