Thanks Dan. I took a look at that this afternoon, but a lot of the stuff I found seemed to suggest that it might be a little aggressive against Douglas Fir. If I can find someone with the kit, I'll try and get a sample blasted to see what it actually does.

Sand blasting tends to strip down the soft fibres exposing the grain. This works nicely on oak, but I think there might be just a little too much soft fibre on the Douglas.