Why must the block be sealed or finished on all surfaces within 48 hours of removing shrink? What can be used that won't change color?

Unfinished wood will draw in moisture, the moisture will cause the grain of the wood to expand, this can cause the laminated wood to warp or twist. This is part of the reason why we oil our butcher blocks once a week.

You can use a clear stain on this item. There isn't any information on why you must seal it within 48 hours.