To neutralize oven cleaner used on wood (usually to draw oil out of the wood), use wood bleach.
Don't use regular laundry breach!!
Wood bleach is oxalic acid, a somewhat weak acid and used in a water soln to coat the wood.
You can buy it in granular form at home improvement store in the paint section. Usually comes in a plastic container . This is the stuff I've always used,,undoubtedly others:
http://www.savogran.com/Information/Wood_Bleach_PD.pdfI mix 3 or 4 tablespoons of the stuff to a quart jar of water. Then put the jar in the microwave for 30-40 seconds. Just enough to warm it up.
Then with the wood wet from flushing the oven cleaner off,,you brush the woodbleach onto the wood. I even dunk small pieces like forends right into the jar.
Do it in a wash basin,,wear old clothes, a shop apron, eye protection and gloves are recommended. You don't want it in your eyes,,it will sting your hands a bit,,it'll really sting any open cut on your hands!
Brush and slosh the stuff over the wood freely. The wood will return to natural color while you're working on it. Black marks and other oven cleaner discolorations will disappear. It'll lighten the wood somewhat (it is wood bleach after all!). When it's of suitable color to you. rinse with clean water.
Pat it dry with paper towels and hang it to dry. You can accelerate the drying with a light touch of a propane torch,,but edges are easily burned as you watch in amazement the moisture drying up.
Be very careful when handling the wet wood. It will be soft and dented easily. All returns to normal when dried.
The water bath doesn't soak in very deeply anyway and a day or so it'll be dry and ready to go.
It'll look like a brand new fresh piece of lumber.
Done it this way for many years.
Works good on any older stock to remove spots and discolorations. Oxalic acid is used by furniture restorationists to remove water marks and the like on finishes.
Some cartridge gun stockmakers routinely bleach the wood on new builds before stain and finishing. They say it gives them a better surface to start with and a more even color base.