It is possible to get "clean" copper..... wait on, what do you mean "red in copper".... To get that copper look they need that tint of red (not red as in red wash - my avatar). This is why I avoid mixing my copper to anything having the slightest red genes.
Without red, coppers will look sort of steel - silverish, which IMO is a different line of coppers - In the past I achieved them from re-breeding the non red ones, incl. the metallic light green. But red will always show on a few of them.
The copper gene we have (in my area) today is very different to those we had in 2005. Today they often throw some platinums, black copper, as well as the usual green. I think this is because they are often used as a mix to create new dragon lines.
This past 2 years of breeding is very confusing because it defies most things I thought I knew about coppers...... maybe I actually never knew anything about them...LOL