The history of window glassmaking in Ireland gains significant traction around the late 17th century. While earlier instances of glass objects exist, the establishment of dedicated glasshouses circa 1680 marked the nascent stages of a local window glass industry. The primary output of these early ventures was broad glass.. This method involved blowing a cylindrical form thorugh a pipe, slitting it lengthwise, and then flattening it. The inherent limitations of this technique resulted in panes characterized by noticeable distortions and an uneven surface, a far cry from the clarity we achieve today. Nevertheless, broad glass represented a crucial step forward in providing more substantial and protective glazing for Irish dwellings. Prior to this, people just used animal skins to protect against the weather. Having glass that brought light into homes was a new phenomenon and reserved for the rich.

Crown windows glass and the Georgian era

The Georgian era (1714-1830) witnessed a shift towards architectural refinement, directly influencing the demand for higher-quality window glass. This was a time of relative peach and stability in Ireland as a kingdom under the British monarchy. Glassmakers in Britain made a new type of glass called crown glass. It was known as crown glass as the first maker is purported to have stamped the glass witha corwn indicating that the tax had been paid.

The process involved blowing a spherical bubble of molten glass and then rapidly spinning it. Centrifugal force transformed the sphere into a disc, thicker at the center (the “bullseye”) and gradually thinning towards the periphery, about 4 feet in diameter. These circular discs were then cut into smaller panes and meticulously assembled into windows. Crown glass offered improved clarity compared to broad glass, although the characteristic bullseye where the pontil rod was attached, and subtle variations in thickness remain identifiable features in surviving Georgian windows. Georgian windows typically are multi-paned grids following the classical rules of proportion. Oftentimes all the panes in a window did not come from the same crown, which makes them even more interesting to look at.

Cylinder window glass and the Victorian era

The Victorian era (1837-1901) brought about further technological advancements in glass manufacturing. This conincided with the industrila revolution as Britain became the first global superpower. The evolution of the cylinder glass process enabled the production of larger and significantly flatter panes with reduced visual distortion. By blowing larger cylinders and employing more controlled flattening techniques on iron tables, manufacturers could achieve greater uniformity in sheet size and quality. This advancement directly facilitated the grand architectural designs of the Victorian period, with its larger window openings, bay windows, and more expansive glazed areas. The ability to produce larger, clearer panes was instrumental in meeting the aesthetic and functional demands of Victorian architecture in Ireland.

Homes featured large single-paned sashes, reflecting a desire for unobstructed views and brighter interiors. This era represented a peak in the quality and size of domestically produced cylinder glass for windows.

However, the early 20th century marked a turning point for the Irish window glass manufacturing sector. The burgeoning global glass industry, particularly the development and widespread adoption of the revolutionary float glass process from the mid-20th century onwards, presented an insurmountable competitive challenge.

The float glass method, developed by Sir Arthur Pilkington in the UK, produced exceptionally flat, clear, and cost-effective glass on an unprecedented scale, rendered traditional cylinder and crown glass production economically unviable for large-scale window manufacturing. Float glass is the modern standard of glass that we have today.

However, the legacy of early Irish glass-making provides a fascinating historical backdrop and informs our understanding of traditional window styles. It gives us an understanding why historic glass is so valuable and should be maintained wherever possible. Our built heritage in Ireland is protected since the year 2000 under the Planning and Development Act Part IV. Local authorities have lists of pretected structures and areas of conservation. Any alterations to windows in these buildings will require planning permission, unless the windows or glass is not original.

Understanding this historical tapestry allows us to appreciate the evolution of window technology and informs our commitment to providing historically accurate yet technologically advanced timber window solutions for period properties across Ireland. By acknowledging the ingenuity of past Irish glassmakers while embracing the advancements of modern manufacturing, we ensure our windows not only respect the architectural heritage of the Georgian, Victorian, and Edwardian eras but also meet the stringent performance standards of the 21st century.