Vintage Margo Soap porcelain enamel advertising sign. By The Calcutta Chemical Co. Featuring the famous slogan. The Genuine Neem Soap. This rectangular 18 x 12 inch enamel board displays the classic Margo soap box illustration along with bold lettering and the Calcutta Chemical branding. Despite areas of enamel loss and surface rust, the vibrant red, green, and blue sections are still visible, giving this piece a true. Details. Product: Vintage porcelain enamel advertising sign. Brand: Margo Soap Calcutta Chemical Co. Beliaghata-Calcutta. Slogan: “The Genuine Neem Soap”. Size: Approx. 18 x 12 inches. Material: Porcelain enamel on metal sheet. Era: Mid-20th century advertising. Colors: White background with red, green, blue text & illustration. Collector Appeal: Perfect for advertising collectors, petroliana enthusiasts, bathroom décor, vintage chemist shop or apothecary displays.