Topic: Early Walsh studio/art trumpet vase — real copper aventurine?

[Bernard C]

Early Walsh studio/art trumpet vase

Click any image to enlarge. Click here for gallery with further images.

Details: Maximum height 9" 23cm Maximum width 6" 15.5cm Foot diameter 4.5" 11.2cm Weight 15oz 429g For a variety of reasons I am sure this vase is John Walsh Walsh, and again I am sure that it was made by the same master glassmaker that made Walsh mother of pearl (see here for an example.) The vase was made in crystal cased canary (uranium yellow or "vaseline") glass with powdered white enamel and what I believe is traditional copper aventurine marvered in before the final crystal casing. Ivo Haanstra, Miller's, 2001 describes aventurine as a 15th Century Venetian development, made with copper shavings, which is what seems to apply here.   It looks as if it was made using a diminutive cheese grater, perhaps the size of a nutmeg grater.   Note the tiny bubbles scattered around the surface of the aventurine.   See the four close-up images below, each clickable to enlarge. I have no experience of aventurine, so would welcome authoritative opinion. Thanks for your interest. Bernard C.

[Cathy B]

What an extraordinary and beautiful piece, Bernard. It would never have occurred to me that it would be John Walsh Walsh. I have nothing useful to add, but wanted to add a reply so that your thread wasn't lost on the next page.

[Bernard C]

Cathy — Thanks for your kind words, but what I would particularly appreciate is an authoritative comment on this piece's possible aventurine decoration.

Bernard C. 

[Lustrousstone]

Certainly looks like copper to me; not all aventurine is copper but I don't think there's copper aventurine that isn't copper, if you see what I mean.

[Bernard C]

Christine — Thanks.   Do you know if the tiny bubbles are typical of copper aventurine?   ... or how they were formed?

Bernard C. 

[obscurities]

Hi Bernard, I am not an expert on aventurine, but here are my observations from the pictures (which is always tough) and my understanding of aventurine, both definition and todays accepted terms and application.

It appears to me in the images that the "pieces" appear more to be "gathers" of fine particulates than flakes", but You can better judge than I since you can hold and look at it.

If they are in fact "flakes" then based on the initial development of aventurine, flakes would not qualify as aventurine.

The initial use of aventurine was an attempt with glass to simulate the look of Aventurine Quartz, which is most commonly found in green, but is also found in other colors.

The shimmering look of aventurine quartz is caused by platy mineral inclusions within the stone which gives it a shimmer referred to as aventurescence. The inclusions are a form of Mica

Initially, very fine particulates of copper were added to glass and evenly dispersed within the glass to simulate aventurescence, which occurs consistently throughout aventurine quartz, and not in pockets.

The term now seems to be generically applied to the use of gold and silver, and also to larger flakes of foil which are "technically" not aventurine.

Although the term is applied to work such as this piece, technically it should look like the attached image..... although the image is a later version of aventurine, obviously Italian, and done with gold instead of copper...

If your piece does have flakes, I personally would refer to it as foil inclusions, and not aventurine.

I hope this helps....

Craig

[Ivo]

Sorry to disagree but the bowl above is a fabulous example of gold dust - not aventurine.

Aventurine was first produced in the 15th Century when Miotti tried to obtain gold glass by adding shaved copper flakes in an acid suspension. It took a long time - but in the end it worked. Aventurine was discovered by chance (aventura) and is not related to the semi precious stone of the same name. The trick was that the glass could not be removed from the pot and had to cool v.e.r.y slowly in the oven. So for a glass maker, it means the pot in which it is made is lost and that is an expensive trick.

It also means that aventurine came in solid lumps as it had to be chopped out of the pot. Larger lumps could be fashioned by cutting - which is a slow and tortuous operation in the best of cases - but the usual way of selling it was in shards and chips. These could be marvered in - either on a dark background or on a transparent one.

The copper shavings would burn at a relatively low temperature and the sparkling effect would be lost. So it could only be used on vessels which were worked at a relatively low temperature. If you see Aventurine in any piece you can therefore be quite sure it is not crystal. Lampwork is a low temperature operation, and the material became available as bars for this.

You often see Dalian vases with aventurine worked into a dark background in which all sparkle was lost by too high a working temperature. But the originals by V. Nason shine like mad.

As you can see in these examples (both Nason) , it makes no difference if the item is blown or pressed.

Green aventurine is a different technical monster based on Chromium shavings. It has a much higher temperature tolerance. Main producer was and is Reichenbach (Germany) and is sometimes found as a solid in Legras pieces.

The other sparkling techniques are silver foil, gold dust (see above), gold foil and Mica.

So we can confirm that the Walsh piece has rolled in shards of aventurine glass.

[obscurities]

Thanks Ivo, See... I said I was no expert about aventurine.... I was absolutely right about that part... 

Craig

[Lustrousstone]

That also explains why it's generally blobby; small glass chips.

[Bernard C]

Ivo — enlightenment at last — brilliant!   I had looked it up in my little library, but the few references I'd found had left me believing that the Walsh master glassblower had incorporated copper shavings, thereby creating aventurine glass.   I couldn't have been more wrong!

So, to be precise, my vase was decorated with white enamel and aventurine.

As you can see, the aventurine decoration in my vase is nowhere near as bright as your two lovely Nason examples.   Is this a symptom of being exposed to too high a temperature, like the Dalian examples you mentioned?   Were the tiny bubbles caused by scorching or burning of the copper in the aventurine?

Walsh management must have been aware of the potential of aventurine — their colouring enamels supplier's representative would have ensured that.   This vase wouldn't have met those expectations.   Is it, perhaps, a trial piece that escaped scrapping?   I've never seen successful use of copper aventurine in an example of British made glass;  do you or does anyone know of examples?   Hajdamach didn't find any (both volumes checked).   Moncrieff's used mica, see here;  others such as S&W used silver foil or gold leaf.

Isn't all this interesting?   Don't concern yourself about being too blunt, Ivo (or anyone else who can contribute).   I think this vase is beautiful, and so does Cathy, bless her little Australian cotton socks.   Who needs more than that?

Bernard C.