Is there a difference in hook strength between stainless and plated after 30 days? Do you have access to a microscope? I will always separate used flies into a quarantined container, wash them throughly in tap water, and let them dry prior to returning to fly box. Never place a fly that's been in the salt back to the fly box. It will contaminate every other fly and eventually cause some degree of corrosion that although might not be visible could compromise hook. And of course wash out real, waders and anything else in contact with the salt which I'm sure everyone does.