How is it done? Each letter seems perfectly lined up and level. Is it all one big plate with the letters standing up out of it? Or each one placed in individually?
Yeah, I’m bored this evening.
image link?
Sometimes it’s a plate. Sometimes it’s individual letters carefully lined up while the concrete is still wet. I would do it just after it’s laid and bull floated. Then lay 'em in there, trowel the bajeezus out of it, and let it set.
The next day you ought to be able to brush it off easily. Concrete doesn’t stick all that well to clean metal. Yeah, it would help to throw some oil on the letters, but you really wouldn’t need to.
Tripler
Oil on your concrete forms however, are a darned good idea.
If they are raised letters on a plate, there’s a thin layer of cement all around the letters that isn’t bonded to anything underneath and this can flake away. Better to braze/solder the letters to a piece of coarse mesh - that way, the top layer of cement is physically joined to the rest of it through the holes in the mesh.
Actually, I think in some cases, the cement isn’t cement at all; it’s some sort of epoxy compound, perhaps with a sand or mineral filler to make it look like cement.