Union Jubilee Clutch.

[Yorkie]

Yup - never, ever, use ordinary steel screws in oak - only use Brass, Phosphor Bronze or Stainless Steel (but only good quality SS).

The tannin in oak is acidic and reacts with ordinary steel forming black streaks...

A similar problem occurs with Red Cedar - I always use PB fixings there... (as do all high quality greenhouses).

Wood-turners often put steel wool into vinegar to make an 'ebonising' solution to stain wood-turned oak items black. Depending on how much tannin is in the oak, this is very effective and looks quite attractive when treated with paste-wax.

Quite a lot of iroko seems to be used for external applications, including things such doors, door jambs, window frames and lock gates, so I assume that's quite durable in such situations but I haven't researched it. I'm sometimes given offcuts of a size that's well suited to woodturning, but few woodturners will touch the stuff due to the toxicity of the dust. That said, it's straight-grained and knot free and turns well.