Topic: what's-'em-a-call-it? on drinking glasses.

[Lustrousstone]

The glasses you find it on are machine made, not hand made I think, and are the cheaper option. Grinding is labour intensive and expensive and then requires rapid flaming to achieve a finish that is acceptable today, which is the way better quality glasses are finished. (You can see it being done at Dartington.) Grinding alone is no longer used but is seen on older cheaper, usually not English glasses.

[Pinkspoons]

Predominantly, but not exclusively. Gerbaud cracking off was instrumental to the designs of many of Per Lütken's heavy - and handmade - crystal drinkware sets for Holmegaard. But because the glass is much thicker than you'd usually find on crystal stemware it's harder to tell.

[scavo]

Thanks Pinkspoons: OK, so it connotes items on cheaper end of the spectrum. Or is it that it gives the 'appearance' of looking cheaper? As in many cases with decorative items - appearance is all ...
I'm only asking because I found some really funky glasses that looked similar to some Holmegaard glasses I've seen on the net ... but I suspected they weren't precisely because of the 'slug', 'bead', safety lip, ?

Lustrousstone: drinking glasses yes - but please look at the link I provided to a very unusual vase I found that has a 'lip' that I doubt could have been machine made.

I think there are 2 different things going on with the same 'lip' type thing.

Pinkspoons: ah, very interesting. So it has been used across the spectrum of glass ...

[Frank]

I think that Nic's suggestion may be off beam and something slightly different... at least it sounds different. I can't find the image of the process on my public sites so it is probably in the Glass-Study... too much material there for a quick search.

I suspect/recall that the technique was an accidental discovery from a faulty fire polishing production facility and some bright spark realised its potential. There would be no 'pip' as all that happens is therim of the finished glass gets heated just sufficiently to melt and as the glass is turning in the flame it just naturally slumps a little. The use of the term safety lip is a misnomer really, just marketing hype, as while it may incidentally add some strength to the glass it primarily reduces the actual amount of glass needed to make a viable product. Thus before the process was adopted glasses were thicker to give the same strength. When a noutter breaks a glass to use as a weapon it makes no difference if it has a lip or not.

I am also fairly certain that the process has also been applied to hand-blown glass not just machine blown.

Best person to give details would be Stephen of Nazeing,

[scavo]

 I'm thinking in the public drinking arena, economies of scale considered, that of course if someone wants to smash a glass and stick it in someone's nanker then you don't really care if it's Holmegaard, Edinbrough Crystal or Ravenscroft ... (errrr, maybe ... 'He did it with style your honour'). Not what I meant about breakages. The really nice ground off stuff gets nibbled on taps etc. That just wouldn't do in pubs, catering etc. I think it's safe to conclude that these glasses are machine made and comparatively cheap.

I'm pretty sure I've got other pieces that look hand made (pretty sure they are free-blown) and they have the thing-em-a-jigg finish. So I guess I'm now interested in how this process is done and for want purpose.
I have what I think is blown Czech glass and also Empoli pieces that are certainly hand done with similar finishing off. With the Empoli pieces it is fairly clear that they couldn't be ground as they don;t have a flat lip (cerated edge almost). But I guess the purpose could be a number of factors - or just 'it's one of the ways ...'

[Frank]

In my experience safety rims do not decrease the chance of breakage when knocked against a tap. I have answered separately on the Neodymium thread you linked to above as that is not the same thing.

If you work the rim of a moulded or blown piece after shaping using a lamp then this localised heating would if the glass is softened sufficiently force it to spread a little, this may be an accidental occurrence or it could be a deliberate design feature.

However in drinkware it can be generally assumed that it is volume production but not necessarily cheap, it is is just an option that the manufacturer has. With drinking glasses intended for the cheap-end it can obviously lead to economies of scale so will be seen more frequently. But it does add a visual difference to a product that may be desired by the designer regardless of other considerations. So while yes it is found predominently on cheap glasses, it is in itself not an indication of cheapness. You are however very unlikely to find it on lead crystal, cheap end or high.

[Ivo]

Arrrgh, was that what you' re on about! I have been told that in mechanical drinking glass production, the finished glass is sheared off hot leaving  a rough rim and the beginning of a thread. The glass is then transferred upside down to a tunnel where a ring of flame melts the rim smooth. The beginning of the thread is melted back and results in a welt. This is more or less pronounced depending on the machine setting.

[scavo]

'welt'

am I getting any closer to the 'technical term'?

This really is fascinating stuff.

So have I got it right?
In mechanical beer/wine or general drinking glass production this is a common feature that resolves the issue of rough edges. It is a method that is more easily mechanised than grinding. Could I also assume that as heating produces a more rounded, less sharp edge that is actually preferable to the hostelry/catering business? It solves (at least) 2 problems in one design feature?

The visibility of the 'welt' depends on the factory machine settings. So sometimes it might be hard spot? Can we assume the finer the 'welt', the finer the glass?

Unlikely to find it used on crystal: perhaps as (I think Frank said earlier) it is a method that allows for less metal to be used in glass production and crystal by definition has to contain more metal. According to Elka Schrijver (Glass and Crystal) 'ordinary' glass = 68% silver-sand, 22% soda, 15% limestone. Crystal = 48% silver-sand, 24% potash, 28% red-lead.(this book is a recent find so not had chance to read it yet).

[Frank]

A welt is a welt.

But the glass does not need to be inverted to do it, but as with everything there are lots of ways to achieve the same end. But you are probably going to deep on this one point - it needs to be viewed in the overall methods of manufacture.

It is not necessary for the rim to be lipped and prior to discovering the benefits of the process rims were not lipped and are not always lipped today.

'Metal' is an industry term for molten glass which derives from glass industry origins related to iron foundrys.

[scavo]

learning, learning, learning!

thanks Frank, everyone.