This article introduces SIGNITE™ as an alternative to ultraviolet screen and digital direct to shape printing for hollow glass container decorating. SIGNITE hybridizes elements of screen, piezo direct-to-shape inkjet and flexographic printing and creates a unique no-look decorating aesthetic using variable data high definition inline printing assets.   

Decorating hollow glass containers dates back to around the same time as when glass making itself began. According to the Corning Museum of Glass, “the earliest demonstrative evidence of a glass vessel decorated with enameling can be found in ancient Egypt. A cartouche found on a glass vessel excavated from Thutmose III, an 18th Dynasty pharaoh, suggests that glass decorating started sometime during the 1400 century B.C.E. 

Since ancient Egypt, variants of the ceramic enameling process continue to be widely used to create permanent decorations on the surface of hollow glass objects used in the packaging of everyday consumer products. Classification of the enamel is based on how the enamel gets its color. The enamel used to decorate glass consist typically of colored glass (or a mixture of colorless glass and a coloring agent) that is pulverized and suspended in a liquid binder. The suspension is painted or printed on to the cooled glass. The pigmented suspension is then permanently fused on to the surface of the glass using intense heat. 

Over the two past decades, photopolymer based ultraviolet (UV) light cured inks have quickly displaced enamel-based inks in many glass decorating applications. Ultraviolet inks represent a viable, cost-effective alternative to ceramic enamel inks. Because they cure at near room temperature, UV inks provide significant energy savings. They also exhibit outstanding chemical resistance and color stability during processing. Because of their growing use in indirect food and skin contact applications, UV curable ink ingredients are selected based on compliance with leading governmental regulatory agencies (e.g., the U.S. Food and Drug Administration), relevant trade associations (e.g., the European Printing Ink Association) and published guidance on packaging ink ingredients from leading industry suppliers such as Nestle.  

Today, both UV screen and UV inkjet printing are commonly used in glass container decorating. Both technologies are referred to as direct printing methods because they apply ink directly on the glass's surface. Screen printing uses screen stations. For each color, a separate inline screen station is used to print decorations. Screen printing is an excellent method for printing on uneven, highly porous surfaces, but it has difficulty in achieving subtle color gradations. Because of set-up costs, screen printing is not very suitable for low volume, variable data printing applications. Conversely, inkjet printing is ideal for ultra-short run, variable data printing, but not well suited for printing on uneven surfaces to achieve high resolution and halftone colors.  

There are many variations on direct and indirect printing currently used within the glass decorating industry. Each has its place depending on the market segment and end-use application. Patented SIGNITE is an indirect print and transfer technology that uses combinations of flexography, piezo inkjet, and screen printing to create a unique no-look pressure-sensitive design. The process is based on UV chemistry, which provides outstanding chemical, scratch, and abrasion resistance. A division of ALTANA Group Wesel, Germany, ACTEGA formulates and produces specialty coatings, sealants, printing inks, and adhesives for the consumer product label and flexible packaging market.     

Like waterslide decal and thermal transfer decorating, SIGNITEis printed inline on a carrier film. The photopolymer clear topcoat (also referred to as the L3 layer) is applied first to the carrier film. The L3 layer functions as a protective overcoat and is then topped with multi-color full Pantone process color printing. The ultra-thin L3 topcoat replaces the need for a face stock and provides structure and a very homogeneous print receptive layer. High opacity white layers and special effects such as metallics and fluorescent pigments can be additively printed in conjunction with process colors. The technology allows for the embedding of holographic and haptic effects into the L3 layer’s outer facing surface.    

For glass surface conformance and adhesion, a UV curable pressure-sensitive adhesive (PSA) layer is applied in registration with the backside of the printed process color graphics. The PSA can be formulated for reversible glass adhesion based on market application needs or glass returnability requirements.  

Compared with conventional pressure-sensitive adhesive labels, the spot application method of SIGNITE decorating process significantly reduces the overall raw material requirements for creating a decoration. As product packaging sustainability is finally capturing the attention of consumers, brands, and global regulatory bodies, there is a move towards more environmentally suitable solutions for labels. In light of this trend, ACTEGA is also investigating the use of industrially compostable and high post-consumer recycle content options to complement the sustainability profile of its print and transfer decorating process.  

Printed media is managed as roll stock once printed by a licensed member of ACTEGA’s decorating network. Once delivered to the decoration house for glass container decorating jobs, printed media roll stock is placed on inline applicator hardware designed for transferring SIGNITE decorations on to glass containers. The process is completed at one of ACTEGA’s decorating house partners in Canada or the United States. 

The decorating process relies on close coordination amongst ACTEGA’s network of printers and glass container decorating houses. The technology can currently address cylindrical, straight walled containers (e.g., wine bottles) with a maximum diameter of six inches and a height of 14 inches and can handle up to thirty 750mL wine bottles per minute. Within the next year, ACTEGA hopes to have a rotary application system for commercialization, which will address non-cylindrical containers with high throughput capabilities. Since the beginning 2020, the SIGNITE hardware technology and media have been commercially used by Schwartz Brothers Printing, LLC in Saint Louis, MO.  According to co-owner John Schwartz, SIGNITE “provides an additional decorating option where our customers can create more complex designs and maintain the high-end look of direct print.” Beginning in August 2020 and despite COVID-19 delays, ACTEGA will also be placing and remotely installing SIGNITE hardware applicators with Zenan Glass, Canada’s largest glass container decorator amongst several other leading glass decorators and manufacturers in North America.     

With scaled demand of its glass decorating network, ACTEGA believes that by year-end 2020, pricing (on a per decoration basis) will be competitive with UV screen printing and short-run pressure-sensitive label decorating. Due to COVID-19 safety restrictions, ACTEGA’s East Providence, Rhode Island Disruptive Printing Technologies Demonstration Center is currently hosting virtual container decorating and application hardware demonstrations. All interested brand owners, design houses, glass container manufacturers, and decorating service providers should e-mail Anthony Carignano, ACTEGA’s Technical Director of Marketing at anthony.carignano@altana.com, to schedule a virtual demonstration event today. 

Name and Affiliation of Author

Anthony Carignano leads strategic marketing and B2B development activities for ACTEGA’s new printing technologies incubator in Rhode Island, USA. Carignano has written numerous articles and spoken globally on the value benefits and aspects of photopolymer chemistry for consumer product packaging and printing applications.