First, I'll show you a pic of the damage, then I'll give you a short background to how this happened, then last I'll ask for advice.
As you can see there are tiny specs in the Tru-Oil finish (one single application) on my black walnut board.
Here's what happened.
I'm making a shelf with these black walnut boards and I did a very good job with the sanding, started with 60 grit (very rough sawn from my friend's saw mill) then 80, 120, and finally 220.
Then, I had to abandon the project for about a week and they sat in my garage (where I also worked on getting a riding lawnmower started). Then sanded them with 320 grit before wiping on a single layer of Tru-Oil. They looked really really great the next day.
My next step was to apply spar-urethane over them to protect from UV and water, but unfortunitally I became pre-occupied with something else and they sat on the garage for some more time, during which it rained extremely hard and some leaks in my roof formed and dripped water onto the floor next to where the boards where laying. Then yesterday I discovered the damage.
So.. it was either caused by water splashing onto the boards and ruining the Tru-Oil (they say it's water resistant but not water proof). Or something like WD40 got onto the boards in-between finish sanding and applying the Tru-Oil and that caused it to react this way. Or... ?
Do you think this is water damage? The effect of WD40 or similar on the wood before the finish was applied? Something else? I think it's water damage but I just want to cover all bases, and I'm surprised that Tru-Oil would do this.
And what should I do? Sand it smooth and start over, or apply a new coat of oil on top? I know that there's a noticeable difference in darkness and sheen from 1 coat to 2 coats of Tru-oil. And if I sand it off and start over, what grit should I start with?