A simple breakfast time question! That a cursory visit to Google has failed to provide a definitive answer.
Jam is 'always' supplied in glass jars, whereas honey/yoghurt/deserts/misc are commonly available in glass or plastic. But why?
The discussion so far has ranged across sterilization issues, customer expectation, age of packaging plants, cost of container as a proportion of selling price, expected shelf life once open, with consequent resealing issues.
Any definitive answers out there?
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Glass has been used for some 5000 years where as plastic is a new boy on the block so it could be just down to tradition maybe.
Plastic can (and does) leach out a nasty toxic substance (BPA) into food and I does wonder if the fruit acid in jam could hasten that process somewhat.
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>> Plastic can (and does) leach out a nasty toxic substance (BPA) into food and I
>> does wonder if the fruit acid in jam could hasten that process somewhat.
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What about vinegar in sauces like Salad Cream, HP, etc?
It's sad about HP Sauce bottles They used to be elegant glass representations of the Houses of Parliament, with moulded lettering "Gartons" and a bi-lingual label in English and French.
Now they are just a nasty squishy plastic travesty, making the same vulgar noise as other sauce bottles.
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HP sauce still comes in glass bottles as well as plastic.
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I think the glass may be to give people the chance to actually see what they are buying? In Germany the supermarket shelves are full of vegetables in glass jars - asparagus spears, baby carrots, kidney beans etc.
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>> It's sad about HP Sauce bottles They used to be elegant glass representations of the
>> Houses of Parliament, with moulded lettering "Gartons" and a bi-lingual label in English and French.
www.flickr.com/photos/30239838@N04/3817294415/
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Daddies sauce is the only one.
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I'd never considered this but have to admit at similar pricing a glass jar would cause me to pick up a jam or marmalade over a plastic one. Perhaps it's a generation thing and the youngsters would be happy with plastic?
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I thought the miniature jam and honey jars had been replaced by those horrible plastic mini-tubs with the unpeelable foil lid, but when we went "on a Warner's" a few weeks ago, they still had the jars.
Maybe they know their market - the oldies would still be in the dining room at 11am trying to get into the plastic ones.
I still buy HP in glass, and Wilkins Tiptree brown sauce too, which is fruitier (for which I go to Morrisons).
Last edited by: Manatee on Tue 30 Apr 13 at 09:38
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Years ago (war time?) my uncle as a young boy shocked his mother by announcing at the dinner table that "Gartons" spelt backwards was snot rag.
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I thought the French translation in the pic linked above looked a bit simplified. This looks like an earlier version -
"Cette sauce de premier
choix possède les plus
hautes qualités digestives.
C'est un assortiment de
fruits d'Orient, d'épices et
de Vinaigre de 'Malt' pur.
Elle est absolument pure,
appétissante et délicieuse
avec les viandes chaudes
ou froides:
POISSON,
JAMBON,
FROMAGE,
SALADE, &c,
et pour relever le goût des
SOUPES,
HACHIS,
RAGOÛTS, &c."
And this seems like an intermediate one, as rendered in song by Marty Feldman:
www.youtube.com/watch?v=VIJnP5W_fF8
Last edited by: Manatee on Tue 30 Apr 13 at 09:45
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>> >> It's sad about HP Sauce bottles They used to be elegant glass representations of
>> the
>> >> Houses of Parliament, with moulded lettering "Gartons" and a bi-lingual label in English and
>> French.
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>> www.flickr.com/photos/30239838@N04/3817294415/
>>
Thanks L'es. Aren't old labels nostalgic?
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>> Now they are just a nasty squishy plastic travesty, making the same vulgar noise as
>> other sauce bottles.
But on the plus side, plastic bottles don't generally break when you drop them ;)
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I'd go with heat resistance and visibility. AFAIK jam is poured into the jars at high temperature and sets after bottling.
Noticed recently that plastic has replaced glass for Waitrose wholenut pnb.
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Peanuts with added phthalates (not sure if terephthalates are leachable so that may be incorrect), and antimony. Shame they've gone the plastic route though.
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Put yer teeth back in, NIL.
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?que Thy're not detachable yet!
Belated recognition of onomatopoeic intent... 1 up to you:)
Last edited by: NIL on Tue 30 Apr 13 at 12:43
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I have seen jam (and pickles too) selling in plastic jars in other countries.
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ASDA stocks some Polish pickled gherkins in plastic bags, from the chilled foods section.
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We have some squirty jam and Branston pickle in the butlers pantry here.
Both in plastique !
Ted
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>> We have some squirty jam and Branston pickle in the butlers pantry here.
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On a point of information, a butler's pantry is traditionally used for storing non-food items, such as linen, serving equipment, and cutlery.
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Not pants, then? That'll explain the disapproving looks.
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My parents had a piece of furniture called a butler's tray. The tray itself was about four feet long and eighteen inches deep, with high rim at the back and sides and lower at the front. It sat on a collapsible X-shaped set of legs at about sideboard height... in fact the thing was a portable sideboard really. Made of mahogany, Victorian I suppose. Can't remember what happened to it.
Would have taken a pretty brawny butler to pick it up laden with massive silver cutlery and big dinner plates.
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Glass is a liquid, so really it's keeping liquid in liquid.
Pointless remark of the day:-)
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Shouldn't a discussion about jam jars be on the Motoring page?
(Had to try hard to out-pointless Roger but I think I managed it.)
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Just not true I'm afraid - just an urban myth. Glass is an amorphous solid.
dwb.unl.edu/Teacher/NSF/C01/C01Links/www.ualberta.ca/~bderksen/florin.html
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I was always taught glass is a supercooled liquid. At normal temperature it still flows, but sooo slowly you cant see it. This is why old windows make the outside look wobbly.
Must be a bit like this:
www.bbc.co.uk/news/science-environment-22337517
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>> I was always taught glass is a supercooled liquid.
Wrong. It's a glass.
>> At normal temperature it still flows,
>> but sooo slowly you cant see it. This is why old windows make the outside
>> look wobbly.
That's down to the production process, actually. (Not float-glass process.) What you were probably taught is that windows in churches are thicker at the bottom than the top because the glass flows. That's wrong too. Glass doesn't flow at all (probably).
Some reading here if you fancy:
math.ucr.edu/home/baez/physics/General/Glass/glass.html
Some solids can flow. The lead on a church roof, for instance, does 'flow' over a long period of time. This is a process called 'creep'.
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Have a look at the fused silica fibres which are used to support the test mass / mirrors on the LIGO gravitational wave interferometer
www.ligo.caltech.edu/advLIGO/scripts/subsystems_sus.shtml
These glass fibres are supporting mirrors where motions of the order of ~10^-12 m/Hz1/2
Any creep or flow in these components would ruin the experiment.
Until it breaks, in terms of its mechanical properties, glass forms one of the most exemplary elastic solids.
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It's very hard so doesn't scratch easily. That smooth impervious surface makes it easy to sterilise by boiling. That's why glass is used to make containers for preserved foods. Its physical characteristics can cause it to crack if it is heated rapidly and unevenly.
I suppose others will have watched glass blowers at work (late in life in my case, as a tourist in Murano). Looks like damn hard work, and a shortened life I believe. But that's industry for you.
Ancient Roman glass is great, obviously highly impure and as a result sort of pearlescent in a good way.
18th century and earlier pre-float glass windows are very rare now. There used to be a shop in Bath that still had a couple of those Hobbity thick panes with a nipple in the middle. But the one I liked best was a haberdasher in the Cathedral Square, Edwardian plate glass but with a couple of clean bullet holes from the war. Still there in the sixties but gone now I bet.
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Ye Olde Cross in Alnwick still has some c.200 year old glass in the windows.
It's know locally as the Dirty Bottles or Dorty Bottles depending on your accent.
Last edited by: gmac on Wed 1 May 13 at 21:28
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What memories of my youth in Alnwick gmac ... 'are ye gannin tae the Bottles Saturday '? was always asked of your mates on a Friday.
The Dirty Bottles was the Saturday night youngsters 'in ' pub when I was a lad in the 60's and it was the 'cocktail bar' where one met the girls from the convent or Duchess School. The drink of choice was beer and there was no music or food - it was considered to be a cocktail if you added water to your Scotch.......
Saturday afternoon was always spent at the Rugby Club , then a few pints and a pie and pea supper, on to the Playhouse for the latest fillum.....and then on to the Bottles to meet up with your schoolmates...and then to the girls accomodation in the College in the castle....if you were lucky.....:0)
Last time I went to Alnwick the Bottles looked a real dive...
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>> Last time I went to Alnwick the Bottles looked a real dive...
It probably always did helico, to anyone not a cheerily drunk late teenage student chasing the vision of ultimate poontang...
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It's got a lovely little lorry park right in the centre and you know where to find it;)
you need narrow gear though)
Pat
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>> 18th century and earlier pre-float glass windows are very rare now.
You seem knowlegeable on glass AC.
What is it about orginal window glass of ordinary 19th and early 20th century houses that makes the panes instantly recognisable ? A sort of slightly imprecise fuzzyness, giving reflections with character rather than the stark bland flatness of modern windows.
Where a window or an individual pane has been replaced it instantly stands out and looks wrong. The correct stuff is unobtainable now, but I believe "horticultural glass" is the next best thing, being just poor quality ordinary glass.
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There must actually still be quite a lot of "pre-float" glass around. Float glass was only introduced by Pilkingtons in the 1960s . The glass is laid on to a bed of molten metal to ensure perfect flatness.
Previously the glass was produced by passing it though rollers like a giant mangle. Plate glass for shop windows etc was ground and polished in an expensive process as rolled glass unlike that produced by the float method is not entireley flat.
The float glass process effectively enabled the glass clad offices we see today.
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>> You seem knowlegeable on glass AC.
Just an impression as CGN has pointed out! Should have realised (or remembered) that float glass was quite recent...
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>> Where a window or an individual pane has been replaced it instantly stands out and
>> looks wrong. The correct stuff is unobtainable now, but I believe "horticultural glass" is the
>> next best thing, being just poor quality ordinary glass.
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You can get hold of proper crown glass these days. It's about £100 per sq metre. This house has it in, for instance. goo.gl/maps/4aHfE (I'm told you can buy cheaper stuff from eastern Europe too.)
www.restorationglass.com/antique-window-glass.htm
www.oldwindowglass.com/
The cloudiness in Roman glass I understand to be where the glass has crystallised.
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>> Just not true I'm afraid - just an urban myth. Glass is an amorphous solid.
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Absolutely correct. I recommend reading and inwardly digesting the Wikipedia page on "Common Misconceptions" to avoid trotting out tired old howlers like "glass is actually a liquid".
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>> >> to
>> avoid trotting out tired old howlers like "glass is actually a liquid".
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I think it's not quite as simple as that. Glass exhibits some properties which are consistent with either state.
www.scientificamerican.com/article.cfm?id=fact-fiction-glass-liquid
"Glass, however, is actually neither a liquid—supercooled or otherwise—nor a solid. It is an amorphous solid—a state somewhere between those two states of matter."
It depends on your preferred definitions. For example, there is no latent heat when glass is melted, unlike with a solid. That might suggest that glass is already a liquid.
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Is glass used because of the acid?
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Where would the advantage be in using plastic jars? Jam is put into the jars whilst hot - around 100C and then sealed. Plastic jars would simply distort and buckle.
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I'm no chemist, but PET has a working temperature range of –60° to 170°C, and melting point of about 260°C, which is pretty robust.
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PET is lemonade-bottle plastic, isn't it? Which means it can take acid and pressure as well as heat. Maybe it's less suitable for a product that will be opened and resealed, not consumed in one go, but I've no idea why that should be.
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Why glass jam jars? - Dog
