Position Papers

Reusing Jam Jars  

15th October 2012

There have been many news stories in the media recently regarding the safety of reusing glass jam jars, arising from advice circulated recently by the Churches' Legislation Advisory Service (CLAS) and the Women's Institute. This has given rise to some concern and misunderstanding about the safe reuse of glass jam jars and bottles. British Glass would therefore like to clarify the following:

  • Glass is inert: it therefore does not react chemically with the food and drink it contains. It remains one of the purest and safest types of packaging available.
  • Glass jars and lids intended for reuse must always be thoroughly sterilised. The risk of bacteria does not come from the glass itself, but can live on in food stuffs that have not been properly cleaned from the container or lid.
  • The Food Standards Agency has stated that interpretation of the EU regulations mentioned by CLAS and the WI was a matter for local authorities.  Individuals or organisations seeking guidance, should refer to their own local authority. To view the full EU regulations in question see Regulation (EC) No 1935/2004 and Regulation (EC) No 2023/2006
  • When questioned about the issue on BBC Radio 4's You and Yours programme on Monday 8th October, Lord Ainsworth of the FSA said "there's nothing unsafe about glass in this context".

A note about Kilner jars

The Food Standards Agency advises anyone making jam for anything other than private personal use to use jars that have been made to be reused –such as Kilner jars, which are produced with the intention that they will be reused.  However, the rules are referring purely to food hygiene standards - not specifically the type of container.  There is no difference in the glass used to make Kilner jars and ordinary jam jars, beer bottles, machine-made tableware and even window glass. It is all made using soda ash, limestone and sand. The only real difference between Kilner jars and other jars is the type of lid. The key point is that any glass container intended for reuse, must be thoroughly sterilised.

For advice on how to sterilise jars properly, a tutorial can be viewed here

Facts about glass containers

  • Glass containers are manufactured to strict UK, EU and International hygiene, health and safety standards, guidelines and legislation. 

  • Impermeability – for all practical purposes in connection with the packaging of food, glass is impermeable2.

  • Glass containers are infinitely recyclable.

  • If the glass becomes dirty or contaminated in use, the hardness and smoothness of its surface and its chemical inertness make cleaning processes effective and reliable.  With other types of containers dirt and bacteria can survive cleaning if there are surface pores or crevices in which they can hide, and if a contaminant reacts chemically with a container surface it will be very difficult to remove; neither of these hazards is likely with glass1.

  • Glass can easily withstand high-temperature sterilization1.

  • Strength – although glass is a brittle material, glass containers have high top load strength making them easy to handle during handling and distribution2.

  • In addition to the above – the glass is “The only material classified as Generally Regarded as Safe (GRAS) by the US Food & Drug Administration (FDA).  (www.fda.hhs.gov)


1 Packaging in Glass (Moody, 1977) Hutchinson Publishing

2 Food and Beverage Packaging Technology (2nd ed) (Cole & Kirwan 2011) Wiley-Blackwell

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Many glass making terms have entered the language: 'Shut yer gob': a molten lump of glass is called a 'gob' to which the glass blower attached a tube to blow the glass into shape. The blower had to blow hard which made his cheeks very large. Today someone with a big mouth is told they have a big gob.

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