The main problem with nylon jackets is that they have a soft flannel lining that is also sublimatable which causes all sorts of problems.  If you don't put paper between the nylon and the lining you will get your image printed all the way through, not only on the shell but on the lining too, which may not sound bad, but believe me, it is.  When you finish and hold the jacket up, the outer shell and the lining will not line up causing a shadow effect that looks pretty bad.

So, the first step is to be able to put something between the shell and the lining.  To do that I cut a 3" slit next to the side seam towards the bottom of the jacket (this will be repaired using seam tape).  I'm sure some people who are more talented with a needle and thread than I, could do a much nicer job by ripping out the seam 3" instead of cutting the lining.  Please feel free to do so at your own risk :-)

Pre-press, pre-press, pre-press...  I can't stress enough how important this is with many materials that shrink.  Always pre-press any material at least 5 seconds and if it is especially prone to shrinkage (like the satin poly materials) press for at least 10 seconds allow to cool a minute or so and press again for another 10 seconds just to be sure.

Using regular Sublijet inks I press nylon at 375 degrees Fahrenheit  for 35-45 seconds .  Other inks will most likely need longer (usually another 20-30 seconds) pressing times .  

In the image to the right you can see after the jacket was pressed but before the protective paper was  removed from inside the jacket. 

I then use iron on seam tape to repair the slit in the jacket.