Here is what US Screen Print has to say
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Most bicycle racing jerseys and pants are made of a very stretchy material called Spandex (also called Lycra). Also, Spandex is used for bathing suits, workout garments and more.
The problem with Spandex is that it stretches far beyond the elasticity of a normal plastisol. With that in mind, you should use a special Spandex plastisol, or add Spandex ink additives to your normal plastisol.
Also, many ink companies make special Athletic plastisol that is much more durable and will stretch farther than most standard plastisols (figure 2).
Since Spandex is 100% polyester, it can also be decorated using sublimation transfers. These transfers can be made using special ink cartridges and an inkjet printer. This will give a print that feels just like the garment (figure 3). Sublimation inks are very transparent so they don't work on dark Spandex. In order to "print" a light colored image on Spandex using sublimation, you have to actually print on white Spandex and print the surrounding "garment" color and entire image at the same time from the same transfer using sublimation ink. | |  | |  | |
Here is the link to the entire article.
U.S. Screen Print & Inkjet Technology
Rutland Ink makes
NX Spand-E-Sol
Wilflex
SSV-FF PLASTISOLS Union Ink's PATH series specifies use on spandex