Topic: Is this vase ceramic or glass?

[krsilber]

Brand newbie here!  This vase has been bothering me for weeks now.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=250250750126&ssPageName=STRK:MEWA:IT&ih=015
I'm less interested in who made it than in how it was made (though the maker would be interesting, too).  Since it was listed as glass, I started a thread about it in a glass forum (http://www.glassmessages.com/index.php?action=post;topic=21477.20;num_replies=21), but after many explanations by glass people that didn't fully satisfy my curiosity finally got up the nerve to suggest it was actually ceramic.  One of the members there directed me to this forum for help.

The main thing I couldn't figure out if it's glass is how the pattern on the "donuts" was made, with the fine, sharp black lines that slightly penetrate the underlying bluish color (as you can see in the photos of the bottom).  The black line bordering the disks was also intriguing.

The brown on the inside seems to me much more characteristic of ceramic than glass.

I'd sure appreciate it if someone here could take a look and offer ideas/opinions - glass or ceramic?  How was the coloring on the disks done?

Thanks very much,
Kristi

[Anne]

Hi Kristi and welcome to the board, you'll find a few familiar faces here as this board was conceived from an idea in the Glass Message Board Cafe forum.

Re your vase, from the bottom it looks like glass - pontil says glass. From the top it looks like ceramic, so I'm as confused as you are!

[Carolyn Preston]

Okay, call me crazy (you won't be the first) but is there anyway it could be ceremic cased in glass? I notice the picture is from the ebay listing. Have you received this piece yet. Do you have more pictures?

Carolyn

[krsilber]

Okay, call me crazy (you won't be the first) but is there anyway it could be ceremic cased in glass? I notice the picture is from the ebay listing. Have you received this piece yet. Do you have more pictures?

Carolyn

Actually, it's not mine.  I'm very curious about glass manufacture (as well as generally ), and this piece was posted on the ebay PGP board and caught my eye and imagination.

Funny you suggest it might be ceramic cased in glass - someone in the GMB forum suggested it was glass with a glaze on it!  The way I figure, many glazes have some of the same ingredients as glass and I've seen ceramic pieces mistaken for glass before.  I don't really see why the parts of this that look glassy might not actually be glaze. 

Hi Kristi and welcome to the board, you'll find a few familiar faces here as this board was conceived from an idea in the Glass Message Board Cafe forum.
Ah, I wondered whether there was a connection!  There are indeed many familiar names here.

Re your vase, from the bottom it looks like glass - pontil says glass. From the top it looks like ceramic, so I'm as confused as you are!

One of the members of the GMB board (Marcus) who used to work in ceramics professionally suggested the bit on the bottom that looks like a ground pontil might have been ground in order to removed bits of the kiln furniture used to keep the glaze from running onto the bottom of the kiln.  The fact that he didn't think my idea that this is ceramic was totally outlandish was reassuring.


I'm almost afraid to explore this forum.  The last thing I need is to develop another obsession - I spend far too much time looking at glass already!  The interest is definitely there, though latent; in high school and university I did a lot of ceramic work, and at one time thought I might get into it professionally, but I haven't (yet) done any collecting.

[Martyn]

My vote is glass...

as I read the photos the base was formed slightly concave, the pontil is just snapped flush and not ground or polised, the base was then ground to make the vase sit flat relealing the opaque white layer seen at the rim showing through the yellow on the ground area of the base. The circle containg the pontil is unground and so has the same surface as the sides of the vase.

I cant quite get my head around the order that the layers were added at the moment and might be completely wrong, but it just does'nt look ceramic to me.

[krsilber]

Usually when a punty is removed, though, the pontil sticks out a bit, while this circle looks recessed to me.

I wish I could handle it!

I just realized something (seems obvious now!).  If the base was ground flat and covered by clear, if it's glass the piece would have had to be annealed to be ground then reheated for the application of the clear.  Doesn't seem very likely.  I see what you mean about it being recessed and leaving that patch.  Hmmm.  Maybe I'll have to contact the seller and/or buyer and see if I get get more photos, or maybe the buyer knows more about it.