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Your Experiences With Stain/s

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So what is your experiences with stains in your making/glazing process?

 

Do they separate or pool when you use them in glaze?

Do they create a course texture when used in a slip/engobe?

What are some of the problems you have had in their use?

 

Just curious?...well more than that.. but

 

Nerd

 

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you might be overthinking this, nerd.  what exactly do you plan to do with what you are calling "stains"?

 

i use a number of colors of mason stains in my slurry and use it as a colored covering, slip.  also use carbonates and oxides the same way.  the stains i use are merely colors.  if i make the slip thick, it will create hills and valleys, similar to tom coleman and whats his name and his melon pitchers.  no coarseness, that comes from adding stuff like grog or sand.  i do not do that.

 

as for separation, i cannot guess what you are asking.

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Lady: I am not thinking in the typical use of stains.

 

Thinking of developing a slip that has higher optical refraction, so less stain is required to achieve color.

Transversely, I have been playing with an optically negative mineral to create mattes: without using the typical formulation of lowered Si/AL ratios. However, it has the unusual side effect of color variegation: which I found most interesting.

 

Was just curious to see the more common uses of stain.

 

Nerd

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Actually, one of the biggest problems with using stains is that they're visually very flat, and can be uninteresting if just added to a glaze or slip by itself. They're a tool in the box that usually need to be layered with other tools. Varigation could definitely be a benefit.

 

I use stains to make my own underglazes. I've been cutting them 1tsp stain to 1 heaping teaspoon EPK and 1 rounded tsp of a flux that's in my clear glaze. I found that my clear didn't like the straight Gerstley borate I was using (the GB over fluxed the underglaze and the glaze crawled over it) and the lithium in the spodumene that was the next nearest jar on my shelf altered the colours, especially on my green.

 

I don't find they settle out of glaze any worse than anything else. They're just flat, like poster paints. One of my projects for the new year is to do a bunch of line blends for varigation, to get some visual interest going.

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Asnd I don't know if this is a common problem, and I rather think it's something in the base slip that's causing it. The artist said she was using a friend's white casting slip as a base for her stains, and putting it over something she called B3 ( I am unsure of the manufacturer: it's not a clay that gets shipped to my location.)

post-63667-0-37451200-1482806593_thumb.png

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I'm not much help as I've just started playing with some mason stains that were given to me, what I have been doing is mixing stain just by eye for color to grolleg porcelain slip out of my slop bucket thinning as needed with water. Paints smooth and no bad reactions firing even when mixed dark, the last couple of pieces were done this way. I've also done second fire on top of high fire with stain mixed with low fire clear, goes on great the results look like poster paint. I also cover some pots completely with grolleg Slip (learned the hard way) when adding a layer of slip vitrify the slip so it bonds to the clay surface of the pot, I've had some glaze almost pop off the whole pot taking the slip with it if just going low fire glaze first after firing as the piece cools and adjusts.

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I mix mason stains thin and use them on my ceramic fish-usually applied with a sponge-then since they are so flat (not shiny) I usually spray a light thin clear over them.

In salt pots I use them in slips  or sprayed wet on slips but the salt fire flues them well.

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Callie/1515:

 

Early this summer I posted a pic of piece that I used a combination of oxides, and modifiers to produce visual effects; both in color and in glaze.

Mountain Lake

 
I am toying/thinking of ways to use slips/engobes to release color or glaze modifiers as I choose to create some new surface/color features with crystalline glaze. Crystalline glaze is about as caustic as it comes: and will leach anything on the clay surface. So I am trying to exploit that characteristic, by adjusting slip recipes to act as color bombs (for lack of better words).
 
Callie: you friend needs to find a handsome prince: her glaze has a case of warts.  (I agree, slip problem).
 
Nerd

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i knew it would not be an ordinary thing you want to do, nerd.  you do not do ordinary.

 

callie, that is the oddest thing i have ever seen, so glad i do not have that problem. :wacko:

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There is all kinds of historical precedent for putting different coloured slips under glazes to alter the colour of specific areas under a single glaze. Shino and Oribe wares, celadon with slip inlay work under it, layering tenmokus to get iron crystal development, just off the top of my head. Putting slips under a glaze that you know will draw colour from anything underneath it is a logical step.

You of all people shlouldn't need encouragement to go make test tiles!

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Asnd I don't know if this is a common problem, and I rather think it's something in the base slip that's causing it. The artist said she was using a friend's white casting slip as a base for her stains, and putting it over something she called B3 ( I am unsure of the manufacturer: it's not a clay that gets shipped to my location.)

Less to do with the slip than the dark clay body. Had this happen to me using Standard 266 with a white slip on the inside. The slip was too thick and the clay could not off-gas properly, resulting in those ugly blisters/pocks. Need a hotter bisque/hold at top temp to get rid of the gases. And thin the slip. Slow the cooling to allow gases time to burn off before the glaze seals. Might be better off using underglazes than slip.

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Callie:

 

I use 50% PV clay, 20% Mica, and 30% NZ kaolin.  Reasons?  Puts the COE right at 6.00: porcelains run in the 5.60 - 5.90 range, and stoneware runs in the 5.75 range (average). Most do not like Mica: but it is the best flux $ to $ because it delivers almost pure potassium, and has a boatload of alumina. When doing slips, not alot of attention gets paid to Si/AL, and even less to alumina molarity. Porcelain runs 14-18 alumina, and stoneware runs 17-20 (average): so keeping alumina in line is a smart idea. I have ran some of the slips I see posted from time to time: most are under 10.00 molar alumina= very weak structure. In addition, the 4.33 molar alkali is more in line with clay bodies as well.

Lastly, PV clay, mica, and NZ kaolin are all white burning/firing clays: adds zero color other than what you intentionally add.

 

Already did the test tiles earlier this summer.  Will be pulling out the first experimental vertical tonight. Will post later. 160C at the moment.

 

Nerd

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Slips (not casting) used for decorating purposes: can be tinkered with in relation to how they reflect under the glaze. All minerals have a "cleavage" numerical value that indicates how it refracts (bends) light. Mica has a perfect crystal cleavage: meaning it will refract light uniformly from every angle you look at it. From there you see values from 100-150 or so: which is an axis/angle of deflection. Sure you have seen in on certain glazes: colors change slightly as the piece is rotated around.

Optically negative is what we call "matte or satin."  Minerals in this case that absorb light instead of reflecting/refracting light.

 

If you notice on the pic above: the bluish areas reflect light, the other areas do not :)  That was not a change in Si/AL ratios: that was a mineral addition the has optically negative properties. There are places that have some, and places that have more.

 

Nerd

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Every stain is different. Some will cause spots if not sieved to 150 mesh. Some will flux a bit. Some are refractory. Some can be used in low percentages, some require high percentages. Some require specific materials in the glaze, others will work with anything. Some cause clumping in the bucket. Some hold color at cone 10, other burn out at cone 2. It all depends....

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Hi,

 

At the moment I'm totally failing to relate your recent posting to my understanding of optics, and my sketchy

understanding of crystallography.

 

What would help me most is references to online papers that discuss the topics you mention.

 

To verbalise my confusion:

 

All minerals have a "cleavage" numerical value ... from 100-150 or so.

- I cannot even image what units these cleavage numbers might be measured in, and I've always thought of

   cleavage and refraction as being essentially unrelated topics (bar the weak relationship through birefringence).

- The only cleavage related "numbers" I can thing of are various cryptographic angles and Miller indices. I had to

   look up the name of the latter, but they are the bracketed triplets describing crystallographic planes; e.g (101).

 

optically negative properties

- A term I'm totally unfamiliar with, although a quick google might suggested that it might relate to birefringent crystals.

- I totally failed to find anything linking "optical negativity" to matte/satin effects. Indeed I'd always believed that these

  were explained by the relative intensities of specular and diffuse reflection.

 

As I said, I hope that reading some relevant papers can help me understand things better.

 

Regards, Peter

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Bruce:

 

stains affected by..  I want the highly caustic nature of amphoretic oxides to leech color from specially prepared slips. May even make the slip, using zinc as a flux. Will have to test that. Zirconium is also on the list: but two rare earth oxides that have really bizarre effects in the right combinations. (See blue tile above).

 

Nerd

 

Peter: much easier than that: some minerals reflect or refract (bend) light, some absorb. If they absorb, then the appearance to the natural eye is matte,

https://en.wikipedia.org/wiki/Prism   Some of the colors we see in a glaze are the results of how light is absorbed and refracted back.

https://en.wikipedia.org/wiki/Refractive_index

 

How sodium absorbs and reflects/refracts light is different than potassium or lithium: strontium changes spectrum. Just think if it as a prism:  the additions of elements into the glaze will turn the prism one way or the other.  Really not that complicated.

 

I just need to go back to gloss, satin or matte: but I just do not think in those terms.. sorry.

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320px-Dispersion-curve.png

 

 

 

220px-Spectral-lines-continuous.svg.png   continuous color band width

 

220px-Spectral-lines-emission.svg.png     colors refracted by sample mineral

 

 

220px-Spectral-lines-absorption.svg.png   colors absorbed by a sample mineral

 

Now go look up potassium, sodium, lithium, barium, strontium, and calcium: they all will have this bar. It will tell you how each refracts or absorbs light. You will notice something about sodium, and it will explain why high sodium in a glaze changes color.  I will let you discover that on your own.

 

Nerd

 

See, now you made me bore everyone to tears again.

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Hi,

 

I seem to have failed to make myself clear.

 

I don't know about "cleavage" numerical value ... from 100-150 or so

Can you reference an accessible paper/article that has such numbers in it?

 

I don't recognise the term optically negative

Can you reference an accessible paper/article that uses the term?

 

That way with some research I should be able to understand your points, and relate them

to my current understanding of optics and crystallography.

 

Regards, Peter

 

Hi,

 

At the moment I'm totally failing to relate your recent posting to my understanding of optics, and my sketchy

understanding of crystallography.

 

What would help me most is references to online papers that discuss the topics you mention.

 

To verbalise my confusion:

 

All minerals have a "cleavage" numerical value ... from 100-150 or so.

- I cannot even image what units these cleavage numbers might be measured in, and I've always thought of

   cleavage and refraction as being essentially unrelated topics (bar the weak relationship through birefringence).

- The only cleavage related "numbers" I can thing of are various cryptographic angles and Miller indices. I had to

   look up the name of the latter, but they are the bracketed triplets describing crystallographic planes; e.g (101).

 

optically negative properties

- A term I'm totally unfamiliar with, although a quick google might suggested that it might relate to birefringent crystals.

- I totally failed to find anything linking "optical negativity" to matte/satin effects. Indeed I'd always believed that these

  were explained by the relative intensities of specular and diffuse reflection.

 

As I said, I hope that reading some relevant papers can help me understand things better.

 

Regards, Peter

 

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