Hi,
Can you tell me the minimum thickness the sandable layer needs to be on an oak tongue and groove floor in order to safely refinish it? My floors date back to 1908 and are ready to be refinished (I've recently pulled up the carpeting that appears to be from the 60's.). It looks as if the floors have been sanded before, so I'd like to know what the standard rule of thumb is before I power up the floor sander. Thanks.

Anything much less than 1/8" above the tongue would be risky unless the floors are in great shape and just need a light sanding.