Bitstream

There have been three suggestions as far as I can see

sand blasting, disk grinder and chemicals

I really really wouldnt choose either of the first two if you have
nice old beams with a patina of age. Once the surface patina has gone
then it is gone forever. Chemical stripping will keep the patina
intact.

TNP: The situation in your house isnt comparable because your timbers
are new, so there was no patina to lose

Anna