Well actually, I don't think there is anything more porous than some chorals, and yet many salt water aquarium cleaners will use bleach to clean the chorals. If you leave it in the air for 4 days, it all evaporates.
We do clean the chorals with bleach and never had one fish die of it. So I am pretty sure your piece of wood will be clean of bleach (eau de javel) the thing you put in with your white clothes to clean and will decolor any other colors
what is an autoclave? Cause I can't put some of the big logs I use in the oven so this is why I use the water cleaning method.