I purchased a number of beautiful vertical grain hemlock doors, and it seems that they had been pre-exposed to the elements. This was only discovered after conditioning and staining one of the doors. As they were delivered on a rainy day, I can only assume that these are water spots in the forms of streaks and droplets. I have not finished with any poly or other sealant. What I have tried so far is to completely re-sand, recondition, and re-stain the slab to no avail.

I would greatly appreciate advice for fixing this problem on the existing, stained door, as well as information for preventing this from happening on the remaining doors I have yet to stain.

Advice appreciated.