Opposite my Hemingray insulator display are some of my favorite signs, including a portion of my burgeoning Stonehouse sign collection (mostly on the right wall in the photo). I developed a fascination with the company's "Danger in an oval" signs and distinct typeface at an early age, around the same time I started collecting insulators. It wasn't until later that I obtained one of their early catalogs and saw their wide selection of power/factory/mining safety signs. The company is still around, now located in Arvada, Colorado: https://www.stonehousesigns.com
If you happen to find any I don't have, drop me a note! I'm especially interested in their early products, including porcelain/enamel coated signs.