My neighbor gave me a magnolia tree he had to cut down. I dutifully cut bowl blanks, cutting out the pith section, and treated the end grain with wax emulsion. My first two bowls were beautiful white wood, which I boiled. 3 days later while drip-drying they became covered in mold spots. Black, brown, yellow, orange and grey. What a mess! Next one I tried vinegar (on somebody's suggestion). The mold loved it. I tried hurrying the preliminary drying by microwaving. I tried Boric Acid dissolved in water and painted on. I tried a solution of the mold inhibitor that you add to paint. The mold ate it up and asked for more.
Finally I got a pound of Sodium Propionate, in a light fluffy powder form. Two freshly turned bowls were treated, one by painting with a solution of 1 tablespoonful in a pint of water. The second by painting with plain water as a control. I did go to school.
The untreated one promptly grunged up as expected, the treated one did not get the spot mold, but after a week was covered with a fine bluish fur. I re-painted this one with a solution of 2 tablespoonfuls in a pint of water and the fuzz went away. A few days later there was pinpoint spots of black. Maybe I am on the right track. The rainy humid weather this year makes drying slow so that should be factored in. After two weeks they still feel wet.
Will keep you posted on the results of a stronger solution. Sodium Propionate is essentially non-toxic in small amounts unless you get it in your eye. They put it in your bread and cinnamon rolls for goodness sake!
This tree has given me plenty of blanks for practice and to perfect my dyeing technique. Hopefully I can learn to lick the evil mold. Will post pictures of the first two bowls after finishing in ABPW. BTW you can't turn the mold off, it rapidly penetrates into the wood.