Silver colors and striking-950 degrees

[gmkcpa]

GA's User Manual on page 18 says "you can grow the crystals yourself. When you are ready to create the nuclei, simply cool the color to a slight orange glow, about 950 degrees F" A slight orange glow at 950 degrees?
For 15 years I've been annealing at 1050. I'll put a marble in the kiln which is already at 1050. After an hour I'll open the kiln door to put in another marble. That first marble is totally at 1050 degrees, and I do not see any orange glow. In fact, I've never seen an orange glow from a piece of glass that is in my kiln at 1050. And I've never seen any glow at 1125 either. The temperature of the glass seems to be real important when flame striking, and the orange glow is real important too, but I don't get an orange glow at 950. So what's the story?

[deb tarry]

I would like this clarified too if anyone would like to jump in. Thanks ahead of time.

[AutEvDesigns]

I want to know the answer to this as well. I seem to recall that this is more important for particular colors - was silver strike 5 one of them? I'll have to look again. I garage my soft glass at 950 and don't see a glow, so I'm not sure I have the eyes to detect a 950 color glow with boro (and, no, I don't see the 1050 glow of my garaged boro, either).

I wondered if some garage time in the kiln at 950 would be the way to go? If no one jumps in, I'll see if I can e-mail the folks at GA.

[evolvingBeau]

Creating nuclei and crystal growth (striking) are two separate steps.
GA adds nuclei to initiate the crystal growth (not sure what they use) to a lot of their striking colors, that's why many of GA's colors strike up really quick.
Striking colors without nuclei, might require a little extra work to coax out the full depth/range of color(s).
I still have a lot to learn about the details of color chemistry but the concept is just one of resetting the color elements in the glass before re-growing the crystals.
I see it kind of like dissolving sugar in water to re-grow perfect crystals. Dissolve the oxides with white hot heat, rest, and start them fresh with a little heat.



from GA's manual;
http://www.glassalchemy.com/index.ph...user-manual/92
"All silver colors should be worked at hot temperatures to create, form and assemble the elements. Once your piece is formed switch to a lower heat, just above the annealing temperatures 1075°F to 1125°F, to grow the silver crystals. The smallest crystals are invisible. As they grow they will create a yellow color. In order of increasing size, the silver crystals will become orange, ruby red, red-purple, purple, blue then green."


Creating nuclei is explained here. (From the same above link.)

"A final note about silver colors and striking: They are not all created equal. Some formulas have nuclei in them, while others do not. Just as a raindrop does not form without a speck of dust, or a pearl without a grain of sand, silver crystals do not grow without something to grow on. GA has added nuclei to most of its silver colors to make them easier to use. However, there are times when the artist wants more control, so we also created colors in which one can create the nuclei. For example, in the colors 383 Silver Strike 3 or 385 Silver Strike 5*, you can grow the crystals yourself. When you are ready to create the nuclei, simply cool the color to a slight orange glow, about 950°F, and maintain the temperature for 20 – 30 seconds. Then heat it back up to 1075 – 1125°F and grow the crystals. The longer you hold the piece at the lower temperature, the more nuclei you create and the more intense the final color will be when you grow the crystals.

Crystal growth and color development is a function of time and temperature. Therefore, a reducing flame, per se, does not create the colors. A reducing flame only treats the surface and can create a multi-colored metallic sheen, or if worked intensely, it can create a grayish sky blue surface of reduced silver fume."

[Bunyip]

Originally Posted by gmkcpa

I've never seen an orange glow from a piece of glass that is in my kiln at 1050. And I've never seen any glow at 1125 either. The temperature of the glass seems to be real important when flame striking, and the orange glow is real important too, but I don't get an orange glow at 950. So what's the story?

Have you tried looking at your piece out of the light, say under your table? That's the method I was told for checking for a slight glow, although it was admittedly in a different context.

[gmkcpa]

Chris-what I'm going to try tonight is putting some color on a 1/2" rod of clear and sticking it in my kiln and taking it up to 1050. Then I'll take it out of my kiln and hold it under my workbench where it is dark. I'll report back. Frankly, I hope it is a little orange, because then I will have my answer!

[e. mort]

When I am putting a sphere in the kiln, I flip off all the lights in the studio so I can see exactly where the glow is. I am sometimes surprised to see a piece that I thought was too cold, glowing away when there is no other source of light.

[constant flow]

I do my striking in the back of the flame, i get much better results than kiln striking. Let cool, heat in the back of the flame till you get an orange glow and count to three-remove from flame let it cool. take a good look at it, if you want a deeper color-repeat.
Do not get white hot or striking disapears and you have to start over, and it doesn't allways work the 2nd or 3rd time!

[AutEvDesigns]

I have an additional question about striking I'm hoping someone can answer: how to avoid getting a veil over the striking color.

Do I understand correctly from the GA user's manual that cooling and just reheating just the surface creates the veil (or sykstals)? How cool can you really let it get in order to avoid getting a veil/skystals?

I know there's a difference between soft glass striking and boro striking, but I thought I heard that, in both cases, you need to cool the glass after forming it before trying to strike it - that you need to put it under your work table and wait until you don't see anymore orange glowing ... but is that too cool? I'm so confused.

[e. mort]

Originally Posted by AutEvDesigns

I have an additional question about striking I'm hoping someone can answer: how to avoid getting a veil over the striking color.

Do I understand correctly from the GA user's manual that cooling and just reheating just the surface creates the veil (or sykstals)? How cool can you really let it get in order to avoid getting a veil/skystals?

I know there's a difference between soft glass striking and boro striking, but I thought I heard that, in both cases, you need to cool the glass after forming it before trying to strike it - that you need to put it under your work table and wait until you don't see anymore orange glowing ... but is that too cool? I'm so confused.

You need to work it in a high oxy flame and burn off the haze before you go to strike it. make sure you don't strike it in a reduction flame or it will re-haze the piece. that being said, sometimes a little haze is a good thing. Can give you some very cool colors.

[AutEvDesigns]

excellent. I'll give that a go. Thank you!