QUALITY CONTROL IN GABLE CUBOIDAL LIQUID PACKAGING

By Tom Kerchiss, RK Print Coat Instruments

Beverage containers are available in a variety of packaging formats including gable top, brick and shaped cartons, pouches and plastic. The ubiquitous plastic bottle is made from coated low-density polyethylene (LDPE), polyethylene terephthalate (PET) and high-density polyethylene (HDPE).  Aluminum foil/metallized film may also be used in composite laminated pouch structures.  Glass also continues to be the material of choice for alcoholic beverages.

Gable top waxed cartons, according to many pundits, was invented in 1934 by the American Paper Bottle Company for the sole purpose of packaging pasteurized milk. The wax coating, employed to protect the carton from moisture was replaced with a heat sealable poly coating.

Gable top, so named because the fold at the top of the carton resembles the gable of a house is experiencing enjoying a surge in popularity. Apart from milk and juice products the carton container in its various guises is proving suitable for a variety of product innovations including, soups, iced coffee/tea beverages, dairy related items such as custard, flavored milks, cream and non-dairy alternatives such as - soy, rice and almond milk.

The gable, brick and shaped carton are said to be the fastest growing segments of liquid packaging, but that’s not to say that there’s not been a few speed bumps on the way. The fruit and vegetable juice segment has been a good market for gable top cartons, particularly in family sized containers, which proved particularly popular in American households at breakfast time. However, in the 1980’s it seemed that this product sector would see its market share eroded by the increasingly popular plastic bottle, which for reasons of economy and changing consumer buying patterns had already captured a major proportion of the lucrative supermarket milk supply from both carton and glass.

A number of factors prevented the blip in the market for beverage carton containers becoming something more serious. To begin with manufacturers tackled the problem associated with the opening and re-closure of cartons designed for containing beverages. Providing convenience and functionality opening/closure systems developed ranged from twist opening cap systems, clip and cut opening systems and straw hole openings. These innovations in themselves addressed an area of frustration associated with using cartons; opening/re-closure systems helped reduce the incidence of spillage and helped keep products fresher.

Another factor in cartons favor is the creative canvas that the (often) cuboidal shape of a carton provides. The large surface area allows brand owners to get their message across and attract consumers with eye-catching designs and creative graphics. 

Many brand owners and marketers are of the opinion that with gable and other liquid carton configurations shelf impact is greater and that consumers view carton board more positively than plastic bottles. Gable top cartons are recyclable; empty cartons can be flattened or crushed incentivizing household waste initiatives. Plastic bottles cannot be crushed making the bagging up of waste for refuse collection more bulky.

An additional benefit of carton liquid packaging is that the opaque structure protects the contents from the harmful effects of light, particular the UV portion of the spectrum. Product shelf life is also considered to be better than with many bottled products.
In terms of production nearly all printing is done on a web fed basis, much of which is either flexo or gravure printed and converted.  Process inconsistencies can arise as a result of colour matching and tension control issues. Inadequate or inappropriate tension measurement and control can impact on print registration: that is the accuracy with which one colour of a printed image aligns with another. Registration accuracy is also a requirement where several webs are being laminated together and need to be aligned or where several visual patterns that are not produced at the same processing point are married together.

Colour variations are particularly noticeable, given that all four sides of the cuboidal carton contain prominent brand logos and other colourful content. A colour that is at variance can indirectly and perhaps at the sub-conscious level harm the brand suggesting that the product contained within is sub-standard. 

Meeting agreed colour requirements time after time and run after run remains a challenge for the printer – for in the sophisticated world of brand packaging its more than just about colour its also about the subtleties associated with tone and depth.   So many processing variables can influence colour outcome including paper/board/laminate brightness, surface quality, and neutrality (deviance from colour cast) all of which can affect the way in which the colour of inks will appear printed on different surfaces. Even a switch to a different paper brand may have a dramatic effect on colour reproduction.

Colour communication devices, sometimes known as sample preparation systems enable users of many descriptions to meet colour targets accurately and quickly and with minimal waste.  One such device is the K Printing Proofer, a bench top device suitable for packaging print companies that utilize flexo and gravure presses alongside each other.  The K Printing Proofer not only is able to proof flexo, gravure and gravure-offset inks it can
also produce wet or dry laminating samples for evaluation.

Another multi-print process/coat device is the K303 Multicoater. This bench top unit is available with interchangeable gravure, flexo and meter bar coating heads. As a standard gravure proofer it is often used in laboratories for quality control on all ink/substrate combinations for colour comparison and also for determining factors such as printability and adhesion.

The addition of a meter bar coating head expands K303 operating possibilities still further. The film applicator supplied with the unit can be used for all types of paper coatings, liquid printing inks, paints, varnishes, adhesives and other surface coatings. Bars are available for wet coatings from 4-500 microns. The accuracy and repeatability of the system make it ideal for the production of samples for quality control and research and development. The samples are suitable for computer colour matching, visual colour matching, adhesion and gloss, etc.

The FlexiProof pre-press flexo colour communication device is now available in three variants, the original award winning FlexiProof 100, the FlexiProof UV and the FlexiProof LED UV This flagship family of devices utilizes miniaturized but exact version of flexo press critical components making it highly versatile and suitable for use for product trialing (pilot runs) in place of a production press. It can be utilized by all members of the supply chain including substrate suppliers, ink/coating manufacturers, etc., valuable when processes or problems need to be highlighted, resolved and documented. In addition to proofing, colour matching, etc., the unit can be used to determine elements associated with printability such as durability, gloss, rub resistance, flexibility, and so on.

RK Print Coat Instruments Ltd
Litlington, Royston, Hertfordshire SG8 0QZ 
www.rkprint.com sales@rkprint.com

Source: RK Print Coat Instruments Ltd