I use the copper green stuff all the time. I use it to treat lumber that is going to be with in 10" of the ground. Deck supports, joists, posts, etc. I get it at home depot. They have a brown, clear, and a green version. There are various amounts of copper in them to give them kind of a good, better, best type of protection. I have used all three at different times. I have about 5 cans of the stuff in my big box van with all of my other tools. I will grab a can and look at it to see if it is the same stuff you are discribing. I would love to coat my hives with the clear stuff, never thought of that. I have been building supers, and mediums all winter and have yet to decide which way I want to coat them. I like the natural look so I was just going to leave them alone, but who knows. I have access to tons of material and building them is no big deal. So I wasn't to worried how long they would last. I will check on the toxicity and see what we come up with. My home depot has a couple of good guys that will be able to tell me. Our home depot up here (Park City UT,) is so green its not even funny. So many tree and rock huggers up here that I am amazed home depot even sell lumber up here. And now with the Sundance film festival in full swing, sprouting that we are all going to die if we don't return to riding bikes and stuff, I am sure its just a matter of time.
Sorry, did I get a little off point there???
I will check on that stuff.