I believe that the swabs are 70% Isopropyl OH. That is the concentration that is
most harmful to bacteria. The 91% probably works better for cooling and
as an after shave- if you are a nonsmoker and do not need perfume.
I predict that the cost per volume will weigh heavily against the swabs.
If removing the top layer of the planks does not work out, you could always
drop back and punt: Stop by Wood Craft - get a packet or two of thin veneer
with an appropriate grain and cover the soiled planking with a new layer.
If you choose Maple,Birch,or Beech, it can be dyed or stained and sealed before it is
attached. Just protect the glue surface side with masking tape or painters tape during
the stain and seal steps, not necessary if you dye. The veneer - you should be able to
cut with scissors and a metal straight edge and #11 blade.