When did bottles stop having seams?
Milk Bottles – Many milk bottles made with press-and-blow machines from the very early 1900s into at least the 1940s resulted in vertical side mold seams that gradually fade out on the neck distinctly below the base of the finish. (Click here for a picture of a typical 1910s to 1940s milk bottle.)
How is the seam method used to date glass?
THE SEAM METHOD – OF DATING OF GLASS BOTTLES At one time almost all bottles were completely hand blown (in the open air) without the aid of molds of any kind. Such work required skilled craftsmen and a great deal of manufacturing time. Small wonder then that in many cases the bottle was more than half the cost of the product.
Where does the seam in a glass bottle come from?
Seam rises completely to the top of Bottle At the height of the industrial revolution, glass manufacturers quickly adapted mass production techniques — instead of molding or shaping the whole bottle by hand in the open air, as was originally done. It was found that by blowing the molten glass into prepackaged molds greatly simplified the process.
Where are the mold seams on pressed glass?
The mold seams are usually found on the sides of the piece where a mold would have fit together during production. Rough mold seams often indicate lesser quality glass, but that doesn’t mean those pieces are not collectible.
What makes antique glass different from modern glass?
Antique glass made from molds might contain grit, whereas modern glass does not. Some old glass also has an asymmetric shape from uneven cooling. Pressed or molded glass often has seams that show the edges of the mold. In early methods, glass molds were clamped together until some of the glass oozed out, leaving rough seams in the glass.
THE SEAM METHOD – OF DATING OF GLASS BOTTLES At one time almost all bottles were completely hand blown (in the open air) without the aid of molds of any kind. Such work required skilled craftsmen and a great deal of manufacturing time. Small wonder then that in many cases the bottle was more than half the cost of the product.
Why do glass bottles always have a seam?
No matter how snug or tight the fit between the two sections (and in some cases three) of the mold, there’s always a rough edge where they make contact–thus creating a seam. It should be remembered that glass manufactures were always interested in, and kept an eye out for, new ways to increase productivity.
How can you tell if Depression glass is authentic?
Read books and articles online, and talk to depression glassware experts to learn the details of the common patterns. Look at the piece under a bright light and from all angles to see all of the small details. This will also help you to determine if the glassware is authentic. American Sweetheart is a very popular depression glass pattern.
The mold seams are usually found on the sides of the piece where a mold would have fit together during production. Rough mold seams often indicate lesser quality glass, but that doesn’t mean those pieces are not collectible.
