You can use the prep spray that att transfers sells.. and it will work.. but You will not get the vivid colors that you do on poly or poly mixes..
It gives you more of a look like confortable jeans lol..
I have all the equipment and liquids needed for lights and darks from Att transfers but it is hard to get the clear directions as to how the procedure goes. Do you use any of this stuff. JoDee
Sublimation dye is translucent, it will show what ever color the substrate is, like putting magic marker on seran wrap. It is best if you use a white substrate to get the best colors. If you are trying to sub on dark shirts, you will HAVE to use a transfer paper designed for dark colors. Which makes using the sub-inks unnecessary, since you can print dark color transfers with standard printers.
You CAN NOT sub on 100% cotton with out adding some sort of plastic or poly treatment. Not now, not ever. The dye will get absolutely no purchase on natural fibers (wool, cotton, hemp... etc.) You HAVE to use Poly or artificial fibers, though using poly blends (like 50/50 cotton poly) will give almost acceptable results.
You can print on a light transfer paper (thus adding a "poly coat"). Again, this makes using sub ink unnecessary, since you can print these on standard printers. This will also add hand, or stiffness to the shirt, though not near what using a dark transfer will. I have also heard rumor that there is a clear coat spray paint that will "add" the poly necessary to natural fibers, but I have never tried it. But I am sure that is going to add a whole slew of complications such as being sure it is properly coated and I can't imagine that the hand to be slight.
All in all, though the poly shirts designed for sublimation is the ONLY WAY to get ZERO HAND. They might seem to be too expensive at first, they are not. I thought I would try to save money by using transfers when I first started, but people can by transfers at one of those other stores and often consider them to be a cheap product. I market my sub shirts to be "Burned right into the fibric, never to crack or peel. It is even safe for the dryer!" that makes your product truly unique.
I buy the shirts for about $5 each, even if you figure high the ink and sub paper are going to be less than $2. I sell adult sub shirts with one 8x10 pic for $25 (s-xl) and $30 (2x-3x). That pays for my design and pressing time too. And people are happy to pay it! They think it is magic! You only need to keep 2 or 3 of each size on hand, and special order more in for bigger projects.
If you would like to try the sub-shirts, try getting them from Derek at Conde Dist. 800-826-6332 ext. 215. Tell him that Amber sent you, and that I said that he (Derek) would take good care of you. He is fast, friendly, and funny. He will also ship you samples of new product each time you order, if you ask. There are several differant brands of sub shirts, and I think that I finally settled on Vapor as the best for color catch and size consistancy. They also have other fibric substrates that will help you grow your business, like mouse pads, baby blankets, purses, wallets, and placemats. You can find them at dyetrans.com if youwant to check them out. They have always done right by me!
I have tried pre-coating and different transfer media for dye-sublimation on cotton - it doesn't look good enough to sell (in my opinion). You can feel the image, if you pull at the sides it will crack, and it looks worse after every wash.
If you are planning to use cotton t-shirts you probably should consider using another decorating method.
I do 50 poly / 50 cotton shirts when i dye sub.. and use the spray from att. You can either spray it on the shirts. or use a fine foam roller and roll it on the transfer before pressing..
The colors will not have the pop that dyesub on 100% poly does.. but depending on what the shirts are for it does have its uses.
There is no peeling or heavy feel with this spray.. (its the soft coat i belive its called) and Have sold alot of these shirts.. and many are return customers..
I have done 100% cotton a couple of times too..
Here is a tank i did that was 100% cotton.. Its had been washed a few times ( i think like 5 times) when i took this picture. .. An example of how it looks is.. it has the look of faded jeans instead of new jeans.. But i have customers that like that look.. so it works then..
Need Help dye subbing cotton tees 
Here is a t-shirt that is on 50/50 after about 10 washes.. If you look close you can see what i mean about the fade..
