Blown Glass: The Ancient Art of Shaping Molten Glass
Blown glass -- formed by inflating molten glass on the end of a blowpipe -- is one of humanity's oldest and most versatile decorative arts, dating to approximately 50 BC in the Syro-Palestinian region. For collectors, "blown glass" encompasses an enormous range of objects from ancient Roman unguentaria to 18th-century American bottles, Victorian art glass, and contemporary studio glass. The category is united by the technique: a skilled glassblower's breath and tools shaping liquid glass into forms of extraordinary beauty and variety.
Major Categories
- Free-blown (off-hand): Glass shaped entirely by the blower's skill using gravity, breath, and hand tools; no mold; each piece unique
- Mold-blown: Glass blown into a patterned mold to create consistent shapes and surface designs; common from Roman times through 19th-century production
- Pattern-molded: Glass dipped into a mold for initial patterning, then expanded by further blowing; creates swirled ribs, diamonds, and other surface patterns
- Pillar-molded: Heavy ribs formed in a mold and expanded; characteristic of Pittsburgh and Midwestern American glass 1830s-1860s
- South Jersey tradition: Free-blown glass with applied decoration (lily pads, threading, prints) in the tradition of Caspar Wistar's 18th-century New Jersey glassworks
- Studio glass movement: Artist-blown glass from the 1960s onward, pioneered by Harvey Littleton and Dominick Labino; Dale Chihuly, Lino Tagliapietra, and others
Identification and Dating
- Pontil marks: A rough scar on the base where the pontil rod was attached; indicates hand-blown production; polished pontils appear on finer wares after about 1850
- Tool marks: Jacks marks (ridges from shaping tools), shear marks on rims, and applied handle attachments all indicate handwork
- Bubbles and striations: Irregularities in the glass (seeds, bubbles, cord lines) suggest early or handmade production; modern glass is more uniform
- Color chemistry: Specific colors indicate period and region -- aqua (natural iron impurities), cobalt blue, manganese purple, and uranium green each have date ranges
- Wall thickness: Hand-blown glass varies in thickness; machine-made glass is uniform
Auction Price Ranges
| Category | Typical Range | Exceptional Examples |
|---|---|---|
| South Jersey lily pad pieces | $1,000 - $10,000 | $30,000+ for rare forms/colors |
| Stiegel-type pattern-molded | $500 - $5,000 | $15,000+ for documented examples |
| Ohio/Pittsburgh pillar-molded | $500 - $3,000 | $10,000+ for rare colors |
| 18th-century American bottles | $200 - $2,000 | $20,000+ for early figured flasks |
| Victorian art glass (hand-blown) | $100 - $1,500 | $5,000+ for unusual techniques |
| Chihuly studio glass | $2,000 - $30,000 | $100,000+ for major installations |
| Murano blown glass (vintage) | $100 - $3,000 | $15,000+ for important designers |
Condition Factors
- Chips and cracks: Any damage to blown glass significantly reduces value; unlike pottery, glass cannot be sympathetically restored
- Sickness: Cloudy, iridescent deterioration from chemical instability (particularly in early soda glass); sometimes attractive, sometimes value-reducing
- Pontil condition: Rough pontils should show age-appropriate wear; freshly ground pontils on supposedly old pieces raise authenticity questions
- Applied decoration: Handles, lily pads, threading, and other applied elements should be firmly attached; loose or reattached decoration reduces value
- Color vibrancy: Strong, saturated colors in early American glass command significant premiums over aqua and clear examples
Collecting Tips
- Early American glass is the prestige field: South Jersey tradition pieces, Stiegel-type pattern-molded glass, and early Midwestern production command the highest prices and most scholarly attention
- Color is king: In early American blown glass, cobalt blue, amethyst, deep green, and amber pieces are worth multiples of aqua or clear equivalents
- Provenance from major collections: Pieces from collections like McKearin, Garvan, or Winterthur carry significant premiums
- Learn to read pontil marks: The type and condition of the pontil is one of the most important dating and authentication tools
- Studio glass is a separate market: Contemporary studio glass follows art-world dynamics -- artist reputation, exhibition history, and gallery representation drive value
- Handle with extreme care: Blown glass is inherently fragile; support pieces from below, never by handles or rims