Topic: Early Mdina cobalt blue sidestripe button rim

[chopin-liszt]

Have you noticed I've been very quiet?
I cannot get cobalt to show up cobalt next to a turquoisey bit showing the turquoise in pics. I have tried and tried, none of my images do the job adequately.
I can see the difference in reality, as clearly as anything myself, but the camera just won't do it.
However, the cobalt in my "new" strapped bottle did come out when it was placed next to my National Treasure. 

[flying free]

  yes I have -
I 'think' if you hold up your fish on it's own against a backlight source , it's possible that it also has cobalt in the mix of the casing in the wings - so in your pics, it's not that your bottle isn't showing the cobalt, but that that fish next to it isn't showing the true turquoise ish
colour it views as to the naked eye.

I strongly suspect that the fish shown in Mark Hill's book captioned as cobalt fish, is not cobalt but perhaps the same as John's whereby the wings are entirely cobalt but not the neck and v. 

Yours I think might be like mine, i.e. having cobalt swirled in the mix for the wings rather than the wings being from the cobalt batch. I'd like to see another photo of your fish on it's own but with the light strongly behind it because it will hopefully show up the cobalt swirls and patches

Is your cobalt streaked new bottle matched to your cobalt charger colour?  is it cobalt streaked or is the whole base glass of the new bottle cobalt blue?
I've linked the pic you attached to a previous thread here - second attachment in your post
http://www.glassmessages.com/index.php/topic,27152.msg164222.html#msg164222

m

[chopin-liszt]

That early fish of mine has no cobalt in it, none whatsoever. 

My bottle has a "diluted" cobalt partial casing, it is not streaky. But it is practically pale navy blue - a completely different shade - it seems to be a warmer sort of blue than the turquoise/teal colour.

My tricorn charger with the seaweedy swirls is pure undiluted cobalt - and is just about impossible to see through.

This is a backlit image of the charger - which does brighten the cobalt colour up considerably.

[flying free]

so your cobalt charger, John's fish wings,  Johns' trailing on his small vase, my sidestripe, the other almost inside out vase (found on another thread), and one of Suzy's almost inside out vases are all the deep inky almost opaque cobalt blue? 

then also I believe my fish has cobalt mixed in and has cased the wings.  And you think your cobalt on your new bottle has been mixed to to a paler version to case your bottle?  I think cobalt was used in a different mixed or diluted format then as well as on it's own.
m

[glassobsessed]

The unadulterated cobalt is not opaque but it is dark. As the cobalt pot was a limited resource it is no surprise that it was used sparingly.

[flying free]

So  does a pot of colour not go very far then?  I've only seen one person gathering glass from a pot and she didn't seem to be taking very much out lol... I can't imagine how many vases could be made with one pot of colour.

Does your charger then fit into the category of  the turquoise with cobalt also swirled into it? 

I'm just wondering whether after using the single pot of cobalt, perhaps  he made a series of pieces with cobalt mixed into the pieces (maybe your amethyst/blue fish included in that as well?) but then gave up on the cobalt altogether?  Is cobalt very expensive?  why would he only make one pot of it?
m

[glassobsessed]

Those are questions I can't answer, I don't have the information needed. There was apparently only one pot of cobalt blue and when it was used up that was the end of it. No idea why more was not available or where it came from in the first place. The quality of the glass available to be used at the very beginning at Mdina was not the greatest, no idea if this was a result of finance, a supply problem or something else.

[flying free]

http://www.glassmessages.com/index.php?action=dlattach;topic=28360.0;attach=26911;image

thanks maybe Tom or Adam might be able to help on how many pieces can be made from a single pot.

John I've been looking closely at pictures you've posted of your fish.  Your fish has three casings - the first one (i.e. innermost to the turquoise neck) looks just like the casing on my fish, cobalt blue mixed with turquoise, to my eye.
The next two outer layer wing casings deepen the colour and look as if they are totally cobalt no mix.  So it seems to me that my vase only got the single casing of cobalt mixed which is the same as the first casing on your vase.  I can see from a photo you posted on another thread where you can just see the first inch of the first casing around the v of your vase. (I've linked the pic above, hope that#s ok)
m

[flying free]

I've been reading Mdina Glass & Isle of Wight Studio Glass - Mark Hill.
I'm not sure I understand it correctly or if I do I have some questions then
On page 21 it says ' two batches of clear, colourless soda lime glass were melted in separate furnaces.  Metal oxides, such as cobalt oxide, were added to one batch which gave colour, in this case a deep cobalt blue.  A gather of glass was then extracted from the coloured batch and rolled in chemicals to modify or change the colour, and add others.

The implication being that only one colour was used in conjunction with clear in another batch, and or in conjunction with rolling in chemicals to modify or change the colour, and add others.  I can't see that description working for either my fish or John's, if they are two colour, neither for the recent fish posted a few months ago that also had a turquoise neck and cobalt wings.  So would it have been the case that both batches of clear colourless glass were coloured rather than just one at some point in production?
My vase is not clear cased. 
and where would the cobalt have been if there'd been a turquoise and a clear batch - there must have been two coloured batches at some point?

[chopin-liszt]

I have no answers at all. Completely clueless.
This thread has been linked to another discussing cobalt, which has brought me back here.

I need to add the very thick inside-out pots with facetted sides cut off to the list of things with cobalt-blue glass. There are a "fair" number of these floating around with cobalt casings, I would think I've probably seen between 10 and fifteen of them in total over the years.

I have also been studying a couple of massively thick Tiger inside-outs, and I'm fairly convinced there is cobalt blue in two of them.

That would mean Tiger got designed by Dobson earlier than originally thought - it would have had to be when the cobalt pot was melted if this is the case, rather than it being after Harris left...



Now I'm wondering if cobalt blue is a descriptor of the colour or whether it means it was produced using cobalt.