Topic: Pink glass vase with color changing to my flashlight

[Lapimano]

Hi,

Actually I dont even know if that is a vase, as this shape is not optimal for holding cut flowers, and the inside has heavy scratching as if it was cleaned regularily just like something related to eating would be. The prominent underside rim of the base has also heavy wear, the rest of the bottom of the base is unscratched, as it is sligltly domed inwards (sorry for possible bad english).

The interesting part might be that if I directly aim my LED flashlight to it, a greenish/yellowish inner hue appears, similarily when i shoot uranium glass with UV light. This one does not react to UV light though, just to my flashlight.

Also the pink color comes from a thin inside layer of pink glass I think, the rest of the glass is colorless.

I was curious what could be the time period and country of origin. I think this is bohemian. I have seen similar stlye items attributed to moser, (but I have a feeling those might be unfair attributions to raise the actual items selling value).

The size is roughly 13cm high, and 18cm wide.

[chopin-liszt]

Hi and welcome. 
It certainly has the look of Moser, but there is quite a lot to unpack here with regard to your questions about colour.
The colours you are seeing other than red, I suspect are just the strange things glass does with colour. Colour in glass does not act like colour in paint.

The colour you see depends on the wavelength of the light hitting the back of your eyeball.
Red and green are kind of opposite colours on the wheel of the spectrum.

I can see from your photos that there is a green tinge on the surface of the rim. The green arises because you are seeing what light is being allowed through the "thickness" of the height of the vessel.
Because it is red glass and very densely red because of the thickness, a lot of the green light wavelengths are not able to enter the body, and get reflected off the surface. The same sorts of things are happening with your flashlight. You'll see green where the light you are using to shine on it goes through a lot of red bits.


Have you ever seen or heard of the Lycurgus Cup? A very famous ancient Roman masterpiece.
It shows the red/green colour change depending on whether the light is on the surface of the glass or coming through it. It has been discovered that it was achieved by a very specific and tiny concentration of colloidal gold particles, but the light and the colour things are based on the same principles. There are images of it here. It's in the British Museum.
  The b*ggers won't give it to me and I want it.

https://www.amusingplanet.com/2016/12/lycurgus-cup-piece-of-ancient-roman.html

I may not have explained this very well. Don't be afraid of more questions or of contradicting me.
This sort of stuff is physics.

 

[Lapimano]

Wow, thanks for the deatiled answer.
I cant really argue with you because I dont exactly understand the physics behind it, but Id like to point out, that its not a thick red glass, as you said, but only a very thin layer on the inside. (I think this technique is called "flashing/flashed"?)

Also I have seen a similar phenomenon with a different bohemian glass from the 1800s where a yellow paint/flashed glass become apparently blue after shooting it with my flashlight (I packed it away somewhere, so I cant check it now, but I think similarily to Lycurgus Cup, this mostly shows from only one side.) Seen this at least two times with 1800s glass.


Any thought abut the purpose of this glass item? Is it a vase?


The Lycurgus Cup looks like a marvel, especially if it was made in roman times, but I think we have to be statisfied with what is available to us. I think many quality glasses are still obtainable for prices affordable to everyone, so there is room to statisfy our greed eh...
Or we can just be happy with what we currently have. I use my favourite antique goblet for occasional wine/syrup drinks. It kinda tastes better from it

[chopin-liszt]

It would really depend on how thick the total pink would be if you were looking down on top of it and taking the three dimensions fully into account, rather than through a thin layer.

What you are finding with your flashlight with any coloured glass will be doing this kind of thing.
Showing opposing colours of the spectrum because of certain wavelengths being absorbed or refracted.

I have some pieces which are bubbly yellow with blue swirls added on the surface.
If I look at it from the bottom, the yellow and blue do not add up to make green.(as they would if it was paint). The blue shapes are purple. The wavelengths which are left after yellow and blue are removed.
I've added a photo of them, but I cannot resize the photo I have of the colour being different.

I can send you a private message, and if you reply to me, I can send you the photo.
Maybe you could resize it and post it here?

I can only use a program my pc won't let me use any more.

[cagney]

  Aspects of this topic have addressed earlier on the board. These links maybe of interest. https://www.glassmessages.com/index.php/topic,70704.msg393693.html#msg393693
   https://www.glassmessages.com/index.php/topic,70717.msg393695.html#msg393695. hope correct.

[Lapimano]

chopin-liszt

OK, send me the photo, and I will try to resize, and upload it here. (I usually use https://ezgif.com/ for this purpose)


cagney

So this phenomenon is quite common with similar red cased glass I see. Interestingly I have an older, 19. century red cased glass, but that one does not perform like this. Maybe its more common with 20. century glass?

[cagney]

  Seems to be very specific to gold ruby. A deep ruby red can be had by the addition of selenium to the batch instead of the gold matrix. Perhaps your other piece a selenium ruby red? Selenium red may exhibit an orange tinge in the thinner parts or edges. Can also be detected by UV light. As alluded to in one of the links the higher refraction of light in lead glass may accelerate this effect.


  I think probably less common these days. It depends on the purity of the gold used. I believe modern batches use gold leaf in the matrix, a fairly pure form of gold.

[chopin-liszt]

I did send you a PM. Check your spam folder just in case. Or send me one.
I can't send you the photo until I get your email address.

(I can only use paintshoppro, and windoze 10 refuses to operate it.)

But you can see in the photo I did post that when light comes through the glass, you start seeing kind of purply browns (on the left hand side of the pieces).

[Lapimano]

I did not receive it. Did you send it here, or to my email address?
I also sent you a message.

[chopin-liszt]

I used the envelope beside your username. That is the only way to make personal contact via this board. It doesn't give out anybody's email addresses.
I haven't got a message from you either. I'm not currently getting notifications, and I did say so in the cafe, I may need to track down the lady who has the pokey stick to fix things.