Actually wood molds were used pre-1800s-1850s. They were usually kept very wet or lined with clay to prevent burning. However, steam from this created a gap between the bottle and the mold, so there is no embossing on wooden molded bottles.Wood mold?! Are you kidding? Bottles molds were made of iron/steel.
What you are seeing is deterioration likely from rust. And the bottle is
a private mold. Not a slug plate bottle. I dug some of these back in the
1980's. This was the only farm dump that ever produced them. Along with
a number of other bottles that we usually didn't find in farm dumps.