I started back turning bowls after a long while

[Cuprousworks]

Isn't it possible that the color change is due to the oil? Flax seed is Linseed, the heat is a catalyst to accelerate polymerization. May there's also an interaction with the moisture being released?

I experimented with leaving BLO flooded boards in direct sunlight for an hour or so, which resulted in very dark finish in oak:

 

[Mike Davis]

Mike, since I don't leave it long enough to char or Torrefi (SP?) You may be closer to the truth.
Although, my first spoon was soaked in Wesson Oil. I would not do that now
for several reasons, but I think the hot oven cured the oil making it less susceptible to rancidity.

 

[Craptastic]

Very nice work and even better knowing you are mending well.

 

[golfdad]

Glad your back at the helm Mike

 

[whitecrane8]

Spectacular