They haven't really tried a wide variety of acids, this isn't a process you experiment with, so it's hard to know if it'd be less finicky with better acids. Acids are quite expensive, maybe a quarter of overall costs.

They haven't really tried a wide variety of acids, failing at that stage ruins your materials and it's something of stabbing wildly in the dark to find anything that works better than the recommended procedure, so it's hard to know if it'd be less finicky with better acids. Acids are quite expensive, maybe a quarter of overall costs.