In BOURBON, STRAIGHT I make the following statement:
Well, it turns out, I was wrong, and I mention it because it is kind of interesting. Straight Corn Whiskey must, indeed, be "not less than 80 percent corn," but Old Charter cannot be called corn whiskey because it, as a bourbon, is aged in new, charred oak barrels. A close reading of the regulations reveals that straight corn whiskey may be aged in "used or uncharred new oak barrels" but it cannot be "subjected in any manner to treatment with charred wood."Old Charter bourbon, which is more than 80 percent corn, can call itself either straight bourbon or straight corn.
I am assuming, and I believe this intent is obvious, that aging in a used barrel that was charred prior to its first use is not considered "treatment with charred wood."