Hi....I'm having considerable success with scorching at the moment and it seems to be very popular in the shop. Here's my method....
I use a plumber's blow torch, the type that screws to the top of a can of gas which is about the size of a large aerosol can. I burn until the surface just starts to show checking....that's the breaking up of the surface into a square pattern which is caused by the rapid shrinkage of the surface due to the heat.
Next I wire brush along the grain to remove all the charred material and the soot.
Next i use a toothbrush to wipe lime wax into the grain, this makes a massive difference and really emphasises the grain. I rub the wax off, vigorously, before it dries, then buff with a coarse wheel that I keep just for this work. Finally I put a coat of microcrystaline wax over it to seal the surface.
The secret seems to be to get a good, deep scorch.
Les