Since there are many different techniques used to work with glass, it can be difficult to determine if the glass was hand blown or made by machine.
Here are a few characteristics you can look for:
Characteristics of Hand Blown Glass:
Pontil mark on the bottom of a hand blown glass vase
Pontil Mark or Punty Mark
- Often called a “punty mark”, a small ring shaped scar on the bottom of a glass bottle. A metal pipe with a thin layer of glass on the end, is used as a handle to hold the hot glass during the shaping process. This handle will often leave on a small amount of glass when separated from the hand blown glass. The pontil mark confirms that the glass is blown by hand. However, this mark can be polished away to hide the irregularity if desired. This means that not all hand blown glass will have a visible pontil mark.
Thinness
- The majority of glass vessels containing a thin wall, is hand blown. However, there are a few companies that will make the hand blown vessel for a wine glass, but then switch to a machine that can create the stem and foot for the bottom half of the glass. Hand blown glass can also be very thick, meaning that you can’t assume the glass was made by a machine if it’s not thin.
Characteristics of Machine Pressed & Machine Blown Glass:
Seam
- With machine blown glass, there will be a seam visible on one side or bottom of the glass object. This seam is a side effect resulting from a machine blowing or pressing the glass into a mold. Most molds are made of 2 or more sides that were carved into, then connected together to create a desired shape. There will always be a small seam from where the mold is attached together.
Thickness
- Machine made glass will typically be much thicker than hand blown glass. With machine blown glass, you will notice a variation in thickness throughout the piece. When a machine blows molten glass into a mold, the outside shape can easily be achieved, but the thickness of the glass will usually be inconsistent from top to bottom. Machine pressed glass will carry the exact desired thickness throughout the object, due to the consistent pressure on the inside and outside of the glass when forming into a mold.
Surface Texture
- Hand-blown glass may exhibit subtle imperfections or variations in texture due to the artisan's touch. Machine-blown glass, however, generally has a more uniform and smooth surface.
Unique Designs
- Hand made glass often features one-of-a-kind designs, colors, and patterns, reflecting the artist's creativity and individuality. Machine-blown glass typically lacks this uniqueness, as it is mass-produced following a specific template.
Price
- Hand-blown glass often commands a higher price due to the craftsmanship, time, and skill required to produce each piece. In contrast, machine-blown glass is more affordable due to the efficiency and scalability of the manufacturing process.
Artist's Signature
- Many hand-blown glass artists sign their work, either by engraving their name or adding a signature cane within the glass. Machine-blown glass lacks this personal touch, as it is produced on a large scale without individual attribution.
In summary, hand-blown and machine-blown glass can be distinguished based on factors such as surface texture, unique designs, price, and the presence of an artist's signature. Hand-blown glass typically exhibits subtle imperfections, one-of-a-kind patterns, a higher price, and an artist's signature, reflecting the craftsmanship and individuality involved in its creation. On the other hand, machine-blown glass has a more uniform appearance, lacks unique designs, is more affordable, and does not bear an artist's signature due to its mass-produced nature.
Dickinson Glass products are all hand blown and crafted by Michael Dickinson in Sebastopol, California.