Gunther & Berns Sheboygan
This is the only known Wisconsin stoneware bottle impressed with the potters mark. It is stamped "GUNTHER & BERNS SHEBOYGAN, WIS." in an oval, and the stamp is inverted. I have seen several like this, and wondered if they were made this way intentionally. However, the upright stamps are much more common, relatively speaking. It is still fairly rare.
In 1863 it was noted that Gunther and Berns stoneware factory produced "bottles for the Gutsch Brewing Company". No stoneware bottles have been found with the Gutsch name on them so it is possible that these bottles were used by Gutsch.