I believe the way it was described to me was first it is pressure washed with HIGH pressure which removes the bark and then dried and then stained and varnished.
There may be some type of material that you could blast with that won't pit too much in the soft areas but I don't know of it. Just my limited knowledge of the subject here.
You could try cob blasting it, it's ground up corn cobs. I used to refinish log homes and we would cob blast off old stains and paints but it leaves the wood pretty rough! We would blast it, sand it, stain it.