On 28 Apr, 08:55, Tim Lamb wrote:

I horrified the Architect by mentioning grit blasting. He strongly
advocates using a wire brush!

Neither are much good - they both have a cutting rate that depends on
material hardness, but doesn't care much about surface depth. They'll
both accentuate any texture or rot that's present.

I'd actually suggest (bizarre though it sounds) a belt sander with a
wide platen. This will tend to flatten variations, not highlight it.
Of course the risk with these is that they're horribly sensitive to
operator error and they'll dig in like crazy if you tilt forwards away
from the platen and onto the roller. They're a lot better if you use
them with a "sanding frame" attached around them, which stops this
tipping.

Makita used to do a gadget that was a 6" wide flap brush, with
swappable brushes from sandpaper shreds to wire. These were good for
cleaing beams, so long as you didn't press too hard and the beams were
reasonably consistent. Using the tips of the bristles gave a flat
finish, pushing hard gave the hardness-dependent behaviour of a small
brush. Cost hundreds though, I used to hire mine. Think Axminster used
to stock them.