I specialize in tanning competitors for bodybuilding competitions. You just need a natural oil that has water and silicon ingredients in it (dimethicone). This gives it slip. Don't use petroleum based oils like mineral oil because it will look blotchy. Also, the skin absorbs the oil after 45 minutes because competitors are dehydrated. So it needs to be applied within 45 minutes of them going on stage. You can either apply it with your hands (I prefer wearing gloves), or you can spray it with a gun (use a separate gun that what you use for your
solution ). Also, because of how Bodybuilders get ready for shows (rather than the other divisions like bikini and men's physique) they need the oil applied right before they get on stage or they get sort of watery. I'm not sure if it has to do with their reload or if it is from pumping up backstage and getting sweaty.