Topic: Just bragging - what I bought today!

[Quackers]

They're not "straw" (shear) marks though (there is only one of those on a piece and it would be on the interior).

Glen, thanks for reminding me about that - I see so many of those marks described as "straw marks" that the term has rather stuck itself into my mind.  At least I didn't say that they were anything to do with the hot glass being rested on a bed of straw to cool .  Is there an acceptable name for those ripple-like marks within the glass to distinguish them from the wiggly surface marks and/or straight mould lines?

Sorry but the more I think about it the more questions come to mind - why would a shear mark only be on the inside?  As I understand it they are caused by the cold metal tool touching the hot glass metal (or is that another myth) so shouldn't that appear on both sides of the glass?

Thanks for keeping me on my toes .

Tim

[Glen]

Tim - great questions! I will answer them as best I can, but I am sure that someone like Adam Dodds can give us more information too. I must say, upfront, that most of what I have learned about the pressed glass manufacturing process - and especially the features of that process as exhibited on the glass - are things that I have learned from Howard Seufer (ex-Fenton) and also from Adam D.

The shear mark is (as I understand it) almost always on the upper surface (in contact with the plunger). It occurs at the point where the gob of hot glass is cut (the tail end of the gob) and thus falls down into the mould. I suppose the glass maker could attempt to flip the gob to the outside, but I imagine that would be physically tricky. I do know that a glass maker might attempt to toss the tail of the glass to the edge of the gob so that it will re-heat. But mostly, on older pressed glass, the mark may sometimes be seen on the upper surface. Sometimes it is covered by a busy moulded pattern, but on those items where there are large areas of plain glass, it can usually be easily spotted (the Carnival piece "Peter Rabbit" often shows a shear mark in the centre).

Later, the shears had a rounded end to one handle, so that it could be used to rub out the mark. But that wasn't used during the Classic Carnival era.

I believe the marks on the exterior (where the piece is in contact with the mould) are caused by a temperature differential between the hot glass and the metal mould. If the mould is cooler than the hot glass, then settle waves may occur as the hot glass skids along the mould surface. These are wavy lines that curve around the outside of the item. As the glass then gets pressed and starts to move, settle waves sometimes form.

If the mould is too hot, the slightly cooler glass can stick to the mould and make lines that can look a bit like fine cracks. I suspect this is what we are seeing on the Four Flowers Vts. They often feature on those items.

One more mark on the exterior is called a lap mark. I'll quote Howard...it's like a "rolled edge line that looks like the line your fingernail would make in an apple skin....caused by the glass gob hitting the side of the mould before being formed".


oh yes...EDITED TO ADD something I forgot - my article on the Shear Mark.
http://www.geocities.com/carni_glass_uk_2000/ShearMark.html

[Cathy B]

Thank you for that explanation, Glen!

Is there a name for the effect that looks like fine cracks on the surface of the glass?

PS - it's good to see you here again! We miss you when you're away.

[Glen]

Cathy  :hug:

You asked a very good question - I will get in touch with Howard Seufer and ask his opinion.

Thanks, everyone, for the fascinating discussion.

[Quackers]

Thanks Glen, I think I'll print that off and keep it somewhere safe!  I certainly understand the shear mark location now - but I'm not sure I've ever seen it... wanders off to look at shelves full of glass

If I ever manage to get to a Carnival Glass Soc meeting  (they always seem to be on days I'm stuck at work) I'll bring a couple of pieces along for a consultation!

thanks again.

Tim

[Glen]

I've heard back from Howard Seufer (I showed him the photo of that green Four Flowers variant on eBay). He has written out very clearly for us what he believes the marks are.  I suspected the metal mould may have been hotter than the glass, but Howard has found evidence in the marks to determine that it was, in fact, cooler than the glass. He also asked Bob Hill (mould shop foreman at Fenton) for his thoughts, which I have also added in the text below.

I am indebted to Howard for his expertise and constant willingness to help.

From Howard:

These lines appear to have rounded edges.   The long line through the pattern is apparently a LAP MARK.   This could have been caused by the gob hitting the edge of the mould, (cooling at that point) and then dropping into the mould; or be caused by the outside layers of the gather chilling too much before entering the mould.   The chilled outer surfaces lap on themselves and prevent the glass from completely filling against the side of the mould.
 
The other lines may have been (again) with the gatherer taking his time winding the glass and chilling the outer surfaces of the gob, while waiting for the presser to accept the glass.   The lines would be similar to the flow mark in the pattern area.
 
Another type of line that has rounded edges and goes into the glass is a TEAR (rhymes with"pear") or a crizzle (shallow crack) that have been healed by reheating the surface.   I believe this is the condition you refer to "make lines that can look a bit like fine cracks" - healed TEARS.
 
The photo isn't clear if the smaller lines are standing out from the surface or are down into the surface.   IF they are standing out, they could have been caused by damage to the mould by the end of the presser's shears scraping the iron while cutting the glass gob.  The mould iron is soft and the shears can dig into the surface.
 
The mould was slightly cool, less than 830 degrees F., because SETTLE WAVES can be seen in the pattern between the Lap Mark and the marie.   This mould was not "too hot".

**

After talking with Bob Hill, former mould shop foreman, he agreed that the smaller lines were probably LAP MARKS also.   He said it looked like a piece that was made when the presser was using glass to warm up the mould and the glass was gathered just too cold.   The piece was one that should have been thrown away on the shop, he said.

My eternal thanks to Howard.

Glen

[Della]

Thank you so much for taking the time to get the answers, Glen :hug: A huge thanks to Howard & Bob too.  :clap: :clap: It is fabulous to read things in simple, understandable terms (especially for a plonker like me!).

[Cathy B]

My eternal thanks to Howard.

Ours too, and our eternal thanks to you, Glen!  :hug: You really are a treasure!  :hiclp: :clap:

[josordoni]

wonderful Glen! thanks so much.

Now we just have to keep using the new terminology (well, new to eBay buyers  ) and get them used to it!

[Quackers]

Glen, that is absolutely superb - thank you so much, and thank you Howard and Bob - the first-hand knowledge is invaluable .

As Lynne says, just got to remember to use the right terms and try to persuade other to do so as well.

Tim