Glass Technology Services Ltd (GTS) is regularly asked the question, What is appropriate due diligence for our packaging? – and this question comes from those who one might least expect, across a variety of organisations in the supply-chain, including both those newly entering the market and long-standing retailers, packers, fillers, wholesalers and manufacturers of glass.

In this column, we present a candid, snap-shot, overview of our typical recommendations for both minimal compliance and good practice due diligence when placing products upon the marketplace or supplying for that purpose.

It focuses upon the glass product itself, so readers must also remember that a range of routine analysis is also required in regard to glass composition, emissions, raw materials and to support suitable process control, such as annealing schedules, coatings and furnace parameters.

Proper due diligence is a responsibility that must be taken seriously and conducted fully before any product is placed upon the market – and that market itself may determine what those assessments should ensure.

Some requirements are put into place through legislation, others are specified by international or national standards and some are simply down to individual retailer specifications or good practice within an end-market sector.

As a result of this, requirements can be complicated and so we often spend time with clients in order to understand their target marketplaces, their in-house and client specifications in order to properly determine an appropriate regime of testing for their ware.

In this article we highlight key chemical and physical testing requirements that we would recommend as a minimum for glass food and drinks packaging.

Legislative Compliance and Food Contact Materials (FCMs)

To ensure compliance with legislation for glass food contact materials, under the EU framework directive 1935/2004, we provide heavy metal content and leachate testing for glass packaging and the test methods used are covered under our UKAS IEC/ISO 17025 accreditations.

The glass heavy metals content is analysed in accordance with the requirements of article 11 of 94/62/EC and framework regulation 1935/2004 - by standard including Mercury, Hexavalent Chromium, Lead and Cadmium content.

Lead and Cadmium content is analysed by ICP-OES - enabling content to be measured in parts per billion – with other elements also reported upon request.

Durability testing is provided against the British Standard BS 6748, EN 1388 and international standard ISO 7086, depending upon the client and market requirements. In addition - where enamelling, specialist colouring and other external decoration is used - Lip and Rim Lead and Cadmium durability testing may also be required.

The European Commission is currently revising Directive 84/500/EEC, which may potentially impact on glass – so GTS is actively involved in this process, reviewing testing requirements and potential limits – which could, in the future, require manufacturers and/or suppliers to analyse a much wider range of elements at much lower levels than previously required.

This is a service that some organisations are already requesting on a voluntary basis in order to report these values to their customers.

Around the world there are a range of requirements, including state-state variations in the United States, which often stipulate cumulative limits for heavy metals content rather than migration.

Elsewhere, many of the methods follow similar models to the ISO, BS and EN standards with variations in the associated limit values.

There is such a volume of individual legislation involved that we cannot possibly cover these all in this article, but in essence the requirements are to analyse the content and migration, or ‘availability’, of these heavy metals and other specified substances.

Quality Assessment, Mechanical and Physical Testing

For glass bottles and jars, we recommend that the client carries out assessment against the published industry guidelines in the long established British Glass TEC document series – developed and adopted by key stakeholders and now adopted on a global basis.

These documents outline a regime of assessments and physical tests that should be carried out to ensure that correct specifications are met and that the items hold sufficient resistance to a range of mechanical tests.

These are performed by companies within the supply chain on a routine basis to ensure that product quality is maintained across batches and between suppliers.

TEC 7, ‘Strength and Performance Standards for the Use of Carbonated Beverage Bottles’, and TEC 9, ‘General Guidelines for the Use of Glass Containers’, are published by British Glass Manufacturers Confederation and the specifications contained within are routinely reviewed and updated by the associated technical committee, comprising representatives from across the manufacturing sector and key stakeholders.

Both guidelines include an array of tests designed to ensure that container glass - bottles or jars - demonstrate adequate physical strength and mechanical properties to ensure their suitability throughout filling, transport, warehousing, retail and end-use and that the items fall within design specifications to ensure that they not only meet the clients design requirements but are compatible with all standard processes. Both TEC 7 and TEC 9 include the following tests and assessments:

Physical Aspects and Mechanical Strength:

Annealing Quality;
Vertical Load Resistance;
Thermal Shock Resistance;
Impact Resistance at Heel & Shoulder;
Hot End and Finish Coating; and
Slip Angle, or industry standard rub-test.

Dimensional Aspects:

Thickness and glass distribution; and

In addition to the above tests, the TEC 7 guideline for carbonated bottles also includes internal pressure resistance testing to the point of failure – including determination of the failure origin and the mode of failure.

Accredited Test Reports

Upon completion of testing or analysis a certificate or technical report is issued to the client.

This enables the client to demonstrate their packaging has been independently tested, is fit-for-purpose and can enter the market. In the case of a failure, it clearly indicates where we have identified concerns or the standard that has not been achieved, together with recommendations to overcome the issue.

Failure and Foreign Body Analysis

Where a failure does occur, either in isolation or widespread, we provide a comprehensive technical failure analysis service to quickly identify the nature of the failure and its root cause – which may include design features, glass quality, manufacturing or processing issues, material interaction, handling or abuse/misuse by the consumer.

In the case of foreign bodies or contamination found within a food product or the glass packaging, we provide expert support to investigate the material composition, surface features, contamination present and its nature to identify or rule-out potential sources of the foreign body in question.

In cases such as potential product recalls, or where further investigation is required, then the team is able to provide wider diagnostic support through technical consultancy, further laboratory support and historic data.

Diagnosing Issues and Technical Consultancy

Where an issue is known or suspected, individual tests can be provided on an ad-hoc basis. In complicated cases these analyses are often carried out in tandem with auxiliary diagnostics support, such as on site technical audits, process investigations, further laboratory analyses, testing and benchmarking.

The expert team draws upon extensive experience, actual data from testing and analysis and any historic trend data and benchmarking available.

In the case of existing clients, previous analysis and test data can be reviewed to investigate trends and further inform the investigation.

This experience and thorough investigation allow conclusions to be drawn as to the cause of such issues and provide recommendations for remedial actions to prevent recurrence and improve product performance.

Specialist Knowledge in Glass

Our reputation and relationship with the client is based on trust, confidentiality and our specialist knowledge in glass. These established relationships, knowledge of the client and product, supply-chain and past experiences allow us to not only give an analytical result, but give priceless feedback on how different parts of the glass supply chain, equipment used, processes or glass formulation may be influencing the different types of issues that arise.

Glass Technology Services Ltd provides analysis, consultancy, testing and research and development support to all parts of the glass supply chain – from raw materials to the end consumer.

GTS prides itself on its confidentiality and independence and is accredited to ISO 9001, 14001 and 17025 standards. For more information please visit, email or telephone +44 (0) 114 290 1801.