we use a poly white, usually wilflex performance white on nylon goods, but, we have all the nylon goods quickly wiped with a rag and alcohol in the image area ahead of time, releases any oils or coatings from the manufacturing process, and then usually mix in a little nyla bond with a certain amount of the ink, only what you think you will need because that stuff will turn the ink to stone in a few days. we've also done some nylon bags and just had to go without the nylabond, doing the alcohol wipe and the ink didn't come off, but I'd prefer using the bonding agent.