After a bit of reserach on other builders' sites, I think that I have not been undertaking the degreasing properly.
I have been using Scotchbrite to roughen the Alclad surface, then spraying on Deoxydine from a simple garden spray bottle, then washing it off.
I have not been working it into the surface particularly well, though, and I'm pretty sure this must be the problem.
So now, after having sprayed on the Deoxydine, I've been using a Scotchbrite pad to really work the fluid into every part of each component, then washing off with even more fresh water than I'd been previously using.
The finish certainly looks better after spraying, so let's see when it dries.
