A question about vat dyes in a glaze

[jsmoove]

Hi there, first post here.  I'm doing some research into photoceramics and I'm wondering a simple question,  (im not that chemically savvy)

What temperature do light-oxidized vat dyes break down under heat?  What temperature can they survive up until?  

This is after exposing fixing and developing the dye.  http://www.pburch.net/dyeing/vatdyes.shtml  

I see here that Vat Blue 4 has a melting point of 470-500c: https://www.chemicalbook.com/ChemicalProductProperty_EN_CB5396425.htm  

Is this the range, or would the dyes burn out at a much lower temperature?  

 

Cheers

 

[Min]

Ceramics uses transition metal oxides for colourants, organic colourants such as the blue dye you linked would burn off long before reaching even low fire or earthenware temperatures. 

[jsmoove]

Hi, thankyou for the response. What temperature do they burn out at? Is it like 200-300c?  

Can dyes be trapped under a glaze, or would the result be same? 

I'm assuming things like indigo glazes are made from some sort of inorganic pigment with an oxide as you say.

Is there such a thing as a photosensitive glaze out there?  

 

[Callie Beller Diesel]

There are photosensitive glazes that will change colours under different light (natural vs incandescent vs fluorescent), but those are made with lanthanides, which are a fun class of oxides on the periodic table that are also referred to as rare earths.  Kinda funky, but I don’t know if  that’s what you’re after. 

What temperature the organic dyes you mention burn out at will vary, but the Vat Blue 4 you mention has a boiling point of approximately 550C. Typical first firing goes to 1000C. Most glaze firings are to hotter than that. No, you cannot put dyes like this under a glaze. 

Blue glazes mostly get their colour from cobalt, or from ceramic pigments that contain cobalt.

What project are you working on that is leading you along this line of questioning? Maybe we can provide some better info if we’ve got more background on what you’re after.

 

[PeterH]

10 hours ago, jsmoove said:

Hi there, first post here.  I'm doing some research into photoceramics and I'm wondering a simple question,  (im not that chemically savvy)

What temperature do light-oxidized vat dyes break down under heat?  What temperature can they survive up until?  

This is after exposing fixing and developing the dye.  http://www.pburch.net/dyeing/vatdyes.shtml  

I see here that Vat Blue 4 has a melting point of 470-500c: https://www.chemicalbook.com/ChemicalProductProperty_EN_CB5396425.htm  

Is this the range, or would the dyes burn out at a much lower temperature?  

Cheers

As  @Callie Beller Diesel says if you can give us some idea what you are trying to do, we would be in a better position to contribute.

PS
1) As to the what temperatures some indigo colours can survive. Recreating highly specialised indigo-based pigments can require temperatures in the range 300-550°C to form them. 

These pigments are based on the molecular-level encapsulation of "indigo" molecules in microscopic channels in a handful of clay-like materials, especially sepiolite & palygorskite.  Real state-of-the-art nanotechnology, but the pre-Columbians got there first with "Maya Blue". 

Indigo chemisorption in sepiolite. Application to Maya blue formation
https://www.sciencedirect.com/science/article/pii/S1631074806000373

Why 300-550°C? Above this temperature the sepiolite crystal structure degrades.

These pigments can be made as a  powder, or applied to ceramic objects (providing the sepiolite/palygorskit structure remains intact).

 

2) maya blue recipe https://www.nataliestopka.com/goingson/postid-6

3) I'm certain that it's best to get the sepiolite or whatever from a artist supplies outlet. Sepiolite forms the basis of some cat litters and small-animal "dust trays", but I'm pretty sure that its crystaline structure has been degraded/lost.  
Kremer look promising https://www.kremer-pigmente.com/en/shop/fillers-building-materials/58945-sepiolite-powder.html#

4) 'ware dust, we are in the world of fibrous minerals best kept out of the lungs. (Kremer's sepiolite claims to be asbestos-free.)

5) Nice page about the open-structure of these minerals
Cookies, Palygorskite, and Maya Blue http://backreaction.blogspot.com/2008/03/cookies-palygorskite-and-maya-blue.html

 

[PeterH]

5 hours ago, Callie Beller Diesel said:

There are photosensitive glazes that will change colours under different light (natural vs incandescent vs fluorescent), but those are made with lanthanides, which are a fun class of oxides on the periodic table that are also referred to as rare earths.  Kinda funky, but I don’t know if  that’s what you’re after. ...

To illustrate @Callie Beller Diesel's point
Techno File: Rare Earths at Cone 6
https://ceramicartsnetwork.org/ceramics-monthly/ceramic-supplies/ceramic-glazes-and-underglazes/techno-file-rare-earths-cone-6/#
int

Dichroic effects are somewhat rare in gemstones, but always elicit a smile when observed or held in a hand as the color change transpires. Neodymium is notorious for possessing dichroic properties in glass, such that the development of a dichroic glaze is not unreasonable. To explain dichroics, I should communicate that the glaze is not actually changing in any way; the quality of light striking the glaze is changing and we can note that by watching the color change in the dichroic glaze. Blue-heavy lights like CFL bulbs, fluorescent bulbs, or halogen street lamps are mostly on the blue side of the spectrum and will cause neodymium to appear a soft to vibrant blue. Incandescent sources and sodium street lamps produce light that is mostly on the red side of the spectrum, thus one would primarily see only a pink/red glaze from the light reflected back. Full-spectrum sources, like some LEDs and natural sunlight, simultaneously reflect back both red and blue colors, thus we see lavender. In (3), a single yunomi has been exposed to halogen, incandescent, and LED lights, showing the three color extremes for neodymium glazes.
 

[PeterH]

4 hours ago, PeterH said:

To illustrate @Callie Beller Diesel's point
Techno File: Rare Earths at Cone 6
https://ceramicartsnetwork.org/ceramics-monthly/ceramic-supplies/ceramic-glazes-and-underglazes/techno-file-rare-earths-cone-6/#
...

Oops: right reference, wrong pix.

[jsmoove]

Hi all,  thanks so much for all this info

What I had in mind specifically was if the product Solarfast could be used in a glaze, it's a light-oxidized vat dye.  I'm thinking about this from a photographic angle, so specifically coating glass with a glaze or vitreous enamel emulsion that I can fire in a kiln, to create a photograph on glass and make it permanent. One product for photoceramics is called "Pyrofoto" by Rockaloid which is discontinued. This contains ammonium dichromate.  

I don't know the boiling point nor the melting point of Solarfast.  I doubt this would work, but im curious.  

For your chart Peter, when at 300-500 the indigo degrades,  is the degradation at the boiling point when it turns to a gas? 

For instance some of these vat dyes have high boiling points: https://www.chemsrc.com/en/Catg/718.html  

 

[jsmoove]

By kiln I was indeed thinking low fire, and vitreous enamels. In the 700-850c range.  

[Bill Kielb]

12 hours ago, jsmoove said:

What I had in mind specifically was if the product Solarfast could be used in a glaze, it's a light-oxidized vat dye.  I'm thinking about this from a photographic angle, so specifically coating glass with a glaze or vitreous enamel emulsion that I can fire in a kiln, to create a photograph on glass and make it permanent. One product for photoceramics is called "Pyrofoto" by Rockaloid which is discontinued. This contains ammonium dichromate.  

I don't know the boiling point nor the melting point of Solarfast.  I doubt this would work, but im curious.  

For your chart Peter, when at 300-500 the indigo degrades

Maybe for these special products make a color test and test fire. Potters are used to doing this and even will apply various clear glazes to observe the color change etc… seems like a little testing is the only way to get a near for sure answer.

 

[PeterH]

19 hours ago, jsmoove said:

...
For your chart Peter, when at 300-500 the indigo degrades,  is the degradation at the boiling point when it turns to a gas?
...

Wrong question. The chart is purely about what happens to the channels in the sepiolite crystal structure.  The authors wanted to remove "the 2nd molecule of coordinated water" without degrading the channel itself. I guess that the indigo just sits there during this process (but becomes eventually becomes slightly better attached to the wall of the channel as the water is no longer there). Even if indigo can stand these sorts of temperature in the protected environment of the channel is says nothing about its behaviour in other circumstances. BTW I'm relying on a several-years-old memory of the experimental to recreation of  Maya Blue, which AFAICR was a wet (or wet then dry) process.

Note however this quote from the earlier reference maya blue recipe https://www.nataliestopka.com/goingson/postid-6
Over the course of a few minutes, you will see the two powders combine and turn a uniform blue color. At 356 degrees Fahrenheit the indigo sublimates to a gas, bypassing the liquid phase, and is immediately absorbed by the clay. Remove the pot from heat and allow to cool. The color will have a violet tinge when hot, but turn turquoise as is cools. You now have Maya blue pigment, indigo locked inside and stabilized by the clay.
... although if you look up indigo in the same Chemical Book you used for Vat Blue 4 you get:
- MP >300 °C(lit.) BP 405.51°C (rough estimate) ... and no mention of sublimation
 ... but then wiki gives:
- MP 390 to 392 °C no BP as decomposes
... so I haven't a clue

PS
I've been thinking about the use of  a photo-sensitive ester of indigo to achieve patterns in fabric, and cannot immediately see how the process can be applied to Maya Blue patterns. I assume that you wash-out the unexposed "leuco esters", and cannot see how a wash-out mechanism can be applied to a ceramic body.

[jsmoove]

Ah...so its the sublimation information that would be useful....I'm way behind on my chemistry terms.  As Bill says, I should probably just try it out and see what happens. No access to a kiln yet, but I'll try and find a place to do it in my area. I was also thinking microwave kiln, I've seen people use enamels in a microwave kiln on youtube.  

The boiling point of some of the other vat dye colours is actually pretty high: https://www.chemsrc.com/en/Catg/718.html Vat Red is 906c.  

I remember reading that certain colors are more light sensitive though.  But yeah no sublimation info.  

As for washing it off, I was thinking the same process as cyanotype, which is gelatin on glass, or you mix the cyanotype with gelatin and coat a thin layer. But I'm not certain how to combine gelatin with vitreous enamel.  I hadn't really thought that far, if Solarfast could last vitreous enamel temperatures I thought maybe there would be a way.  

[Callie Beller Diesel]

Just because a dye doesn’t boil to a certain point, that doesn’t indicate whether or not it might denature in another fashion. You really would have to test for sure. 

When I was trying to find a little more information or SDS sheets for the Solarfast and the Pyrofoto, it didn’t look like the Solarfast would hold up to enamel temperatures. BUT, I did notice that some of the other sensitizers on the Rockaloid website did mention they could be used on ceramic. It might be worth it to reach out to them for further clarification, or for suggested use. 

[jsmoove]

Yup, makes sense, seems like there are a few factors for degradation. Where did you find the temperature information for Solarfast? I'll definitely test it out when I get the chance. 

Yes, selectacolor on the rockaloid site is a dichromate, I think most photoceramic methods rely on this, it's banned in europe now though. I was thinking at least with dyes there wouldn't be any hazardous fumes like with dichromates, or cyanide gas in cyanotype.  Pyrofoto is discontinued now, also dichromate.  

[Callie Beller Diesel]

@jsmoove I think it was just on the SDS sheet. 

[jsmoove]

I don't see any info on the SDS: http://www.dick-blick.com/msds/DBH_SDS_48933XXXX.pdf  I've asked Jacquard, so they should be able to fill us in.  

[jsmoove]

-Jacquard does not know the boiling or decomposition point of their Solarfast.