Many experiments have been carried out with different natural fibers and blended natural fibers (eg 50/50 cotton t-shirts) and mostly using true sublimation printing on fabrics it is best to use polyester fabrics.
Some report success with 50/50 cotton t-shirts, but most prefer to use readily available digital printers that have the correct ink to adhere to the cotton or screen printing ink that also matches formulated cotton or 50/50 t-shirts. Nowadays Dye-sublimation shirts are very popular and most people prefer to wear these shirts.
Why are fabrics other than polyester not suitable?
Because the pores of the substrate must hold the dye when the pores are closed, cloth or other substrates will not hold the dye. So if you need to sublimate a 100% cotton t-shirt, cotton doesn't have the chemicals needed to close the pores around the ink so it sticks to the material or substrate. Keep in mind that sublimation will also not work on dark substrates, and white or slightly off-white materials always work best.
What works for other networks?
There are types of heat transfer seals that work well with cotton or natural fibers that chemically bind the ink to the cotton. This process couldn't identify due to limitations gives overprinted fabrics a soft feel with excellent color, vibrant color, and washability. similar to an actual sublimation printing on polyester fabrics.
Compared to screen inks, which can also be used on cotton t-shirts, these heat transfer dyes don't stick to fibers like screen inks and are especially useful when full-color photos or images are desired.