Wire Tempers from Soft to Hard:
Annealed (softest): Used for chain wires and for stitching the wire to the ribs.
1/2 Hard: I believe that Amies used this for laid wires.
3/4 Hard: I have been using this for laid wires with good results.
Full Hard: I have been (mistakenly) believing that this was harder than Spring Temper.
Spring Temper (the hardest wire I’ve used): I used this exclusively for years, purchasing it pre-straightened. For several years I’ve been straightening it for laid wires with good results. It may be stronger than necessary and harder to straighten than 1/2 or 3/4 Hard.
My Misunderstanding:
Until recently I have been thinking that Full Hard was harder than Spring Temper. I have successfully made laid wires from 1/2 Hard, 3/4 Hard and Spring Tempered CA510 Phosphor Bronze Wire. I’ve never used Full Hard. I’ll correct these posts soon but wanted to set the record straight. I don’t actually know which is best but I’ve settled on 3/4 hard as my preferred wire for laid wires.
Timothy Moore Bookbinding Tools 