Sorry if i offended you i am genuinely interested in your design/concept, i accept what you you said about the surface of the hide not being abrasive, i havent posted this in your thread because i dont want to appear to be trying to score points of you but if the sand comes off with rubbing ,how do you intend to keep it clean? a algae build up (like you get on rocks) could give it quite a nice finish but you do get a bacterial build up which occasionally requires a good scrub, if the sand comes off with contact your going to end up with bald patches, ruining the appearance. Do you think a second coat of silicon over the top of the sand to bond it in be beneficial? Took your point about framing things as questions lol