with surfboards they use ink and stickers but it doesn't matter because they coat them with a clear resin after its done to seal it all in. salt won't effect it. with clothing i would say it depends on what your doing. it it's lycra then you need to add to your ink to make it stretch. you also might wanna look at vinyl. i have never done surf stuff but i used to build surfboards a long time ago and that was how we used to do it (i would assume the process is not much different now). look at some stuff and see if you can tell what process they did. also call the ink manufacturer and ask them.