Dark T-shirt sheets, and a few Light T-shirt ones. I generally like the Dark T-shirt ones better because I use a lot of dark fabric, and I like pressing it onto black cotton. But the Light T-shirt ones work well for certain images. It was also way easier to press with the iron and peel the backing paper off.
Tip: Make sure you use a de-fuzzing sticky roller or something to remove fluff from the fabric before ironing. Even the most microscopic bit of fuzz will be super visible on the white parts of the image after you iron it. Go crazy on the fabric and brush off the transfer with a dry paintbrush.
I thought I would include some pics of my horrible failures. You know, so you can feel better about yourself. I mixed up The Dark and Light T-shirt transfers when pressing them, and since they have different processes, this happened. That black and white teapot is part of the disaster sheet.
The full page tea set was going to be a zipper pouch, but I neglected to remember that after sewing a zipper pouch, you press it flat, and you cannot iron a transfer once its set on paper. So...I am going to make something else with the tea set. Appliques probably.
So once the transfer was on fabric, I backed it in black cotton and zig zag stitched around the outside. My early 2000's Singer did not like to do this at all. But my early 1970's Singer just breezes through.
I made a few, photographed them and listed a couple of them in my Etsy Shop. I am keeping the "1st Place in Disinterest" for my own jacket, because I try not to care about things that are stupid. Its a lifestyle.
So I guess the experiment was a partial success. The images look crisp and they are nice and flexible. I still think this counts as a "test batch" though as none of them are quite perfect.
Heat transfers are fussy, and its easy to mess up, and every time I make a project with them there are some failures. So if you try it, and royally screw up some images, just remember this post and then immediately go and eat a cookie.