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Glass Identification - Post here for all ID requests => Glass => Topic started by: Paul S. on October 03, 2010, 07:39:20 PM

Title: pressed candlestick with Manganese
Post by: Paul S. on October 03, 2010, 07:39:20 PM

by way of interest as well as requesting an id, if possible.
Accustomed to seeing clear glass giving slight greenish reaction under uv, due to presence of some manganese - often included, apparently, to de-colourize some of the impurities in cheaper glass  -  a lot of the C19 Celerys produce this effect.
However, wasn't aware that, when proportion of Manganese increased then there is effect of creating attractive Amethyst or purple  colour in the glass - such as this stick.    This is one of the most attractive sticks I have seen  -  simple and a pressed piece only  -  but really good quality, with perfectly round concave pontil mark, beautifully polished in the middle of a ground and polished, completely flat base.   Top is also ground and polished flat.   7.5/16" - 185mm tall.   I only have the one, unfortunately.   The green in the last pic. is really striking.    Probably little chance of getting an attribution, but in anyone does recognize it please let me know, and thanks for looking.

Title: Re: pressed candlestick with Manganese
Post by: Lustrousstone on October 04, 2010, 11:16:55 AM

Quote

However, wasn't aware that, when proportion of Manganese increased then there is effect of creating attractive Amethyst or purple  colour in the glass - such as this stick.

Not in this case I don't think. Looking at the candlestick and reading your description, I would say yes there is a lot of manganese but not enough for the purpling to be deliberate. That looks likes sun purpling of a late 19th C or early 20th candlestick in colourless glass IMHO.

Title: Re: pressed candlestick with Manganese
Post by: Paul S. on October 04, 2010, 12:14:23 PM

Thanks Christine :) - I may well have got this wrong then.    I had obviously picked up on the fact that - in former times -  Manganese was added in greater proportions than if being used simply as a decolourizer  -  to induce shades of rose, amethyst and purple, and in the flesh this piece seemed to have a fairly strong amethyst tint.    I don't really have any experience or knowedge of 'sun purpling' - I must investigate this a little more, and try to get to see a real deliberately coloured piece.     However, this is a quality stick, so I will keep whatever the actual reason.   thanks again.    Paul S.

Title: Re: pressed candlestick with Manganese
Post by: Lustrousstone on October 04, 2010, 02:01:20 PM

I don't think it's coloured enough to be deliberate in this case.

Title: Re: pressed candlestick with Manganese
Post by: Ohio on October 04, 2010, 02:14:06 PM

Magnesium Dioxide was used as a decolorizer & will react direct sunlight over a period of time causing sun purpling which looks to be the case with your candlestick. Not uncommon. Ken

Title: Re: pressed candlestick with Manganese
Post by: Paul S. on October 04, 2010, 03:41:03 PM

thanks Ken - really appreciate the helpful advice. :)

Title: Re: pressed candlestick with Manganese
Post by: Anne on October 04, 2010, 04:44:38 PM

Paul, have a read through this page, it'll help make what happens clearer (or purpler maybe!)
http://www.patternglass.com/sunpurple.htm

Title: Re: pressed candlestick with Manganese
Post by: Paul S. on October 05, 2010, 01:20:56 PM

thanks Anne - have read your link, and seems quite a complex issue.   Some of Elaine Henderson's encounters make for very depressing reading.     The real things are very attractive indeed.    Paul S.