I just unloaded a "strinking" test from this morning's bisque. I sent pice which had been single dipped in an iron rich glaze and fired to ^6 back through a ^07.5/^06 bisque. Incredibly different results. I wish I'd taken a before picture for comparison. Before it was an ugly brown with spots of tomato soup red where the glaze was a bit thicker; high gloss finish.
It sounds like I have very similar results to Babs. Now it's a very consistent orangey-red with a slightly less glossy finish. I'm excited to now try a piece that had a nicer red glaze coat after the first firing and see how that compares. I'm on the hunt for a foodsafe true red.