Can’t be any worse than defoliants. Well, I have thought about that. I can blame Agent Orange if there’s a problem. I think breathing in the spray is one thing; emanations from the resulting hardened surface are another. Not sure what to say on this. Since the coating would add some mass for the whole length of the reed, I’m not too worried about that. But the reeds can always be tuned. I’m not going to experiment on one of my good melodicas, however.