of the lighter blue mason stains which has the least opacifier?

[oldlady]

looking for a mid-range blue for min's clear recipe that has a minimum of opacifier so it will be as clear as possible.   i have cobalt carb and the following blue stains :  mazerine, vivid, cerulean, robins egg, deep turquoise and zirconium vanadium blue.   i also have deep orchid which has no purplish at all, comes out wishy washy blue in every test.

i want to keep the glaze transparent so the feature noticed is the impressed plant material.  my other glazes take away the crisp distinctions i want and flatten out the texture too much like covering with a blanket.   pansy purple and the deep green are great but i want to branch out into colors. 

real  gingko leaves come out so well that they could be made of human hair and each one is visible.  i do not want to lose that effect.  any ideas or is this a mason tech person question?

[Bill Kielb]

1 hour ago, oldlady said:

real  gingko leaves come out so well that they could be made of human hair and each one is visible.  i do not want to lose that effect.  any ideas or is this a mason tech person question?

I think definitely a mason person but just to share, this was sort of  put together, less than a percent of stain as I recall in a high gloss clear and I was completely satisfied how the underglaze and carving  is very distinct and visible. Not as fine as you are seeking but encouraging nonetheless that you will find a combination that works for you.. I think we did one test at 1/4, 1/2, 1%  (something like that)  and picked a final value from there. Sometimes things just work out easy.

[Hulk]

Hi Lady!

Not sure if this is transparent enough - Lakeside Clear Blue.
The chattering (filled with glaze, wiped back, and dried before dipping) and underglaze pattern show through.

Over white stoneware, if not too thick this blue is fairly "clear"...let me know if you want the recipe.

[Min]

Cobalt is going to give you a more transparent glaze than stains as it becomes incorporated into the melt whereas stains don't dissolve, they basically are suspended in the glaze melt. To answer your question about opacifiers, the Mason stains that have zirconium as part of the stain structure are 6364 Turquoise, 6374 Dark Turquoise, 6376 Robin's Egg and 6315 Zirconium Vanadium. I wouldn't let that be the deciding factor though. If you do try the cobalt you might want to add some manganese and/or iron oxide to it to tone down the intensity of the blue. You also will probably find that if you use more than just a fraction of a percent of cobalt that it will make your glaze more fluid, which actually might help get the effect you are after.

[Callie Beller Diesel]

I use .1% cobalt in a clear base. So 1/10 of a gram in a 100g batch. I also use a few mason stains in the same base, and find if you fire it on the hot side (cone 7), they tend to incorporate into the melt more thoroughly. But you have to watch your base composition. The ones that don’t burn out the pinks and the yellows also seem to have just enough barium and strontium to encourage colour response.

[Magnolia Mud Research]

10 hours ago, oldlady said:

i want to keep the glaze transparent so the feature noticed is the impressed plant material.  my other glazes take away the crisp distinctions i want and flatten out the texture too much like covering with a blanket. 

You want a transparent glaze.  
Therefore you want a colorant that will be dissolve into the glaze melt and stay dissolved on cooling.  Take your best simplest bright clear glaze and add cobalt carb;  to get a blue tint without being a blanket will mean that the amount of cobalt will be significantly less than 1%.  Callie is using 0.1% start there and move up or down.  

the thickness of the glaze layer is significantly correlated to the "blanket" effect on surface textures -- thin is better than thick. 

LT

[oldlady]

thank you, that is what i want.   i use that darker cobalt blue often but i am trying to find something more like sky blue.   i will try the very tiny percentage you suggest.   still would like a sky blue, though.   i love the cerulean slip but the pieces i want to do in sky blue will have only glaze on them.

2 hours ago, Min said:

Cobalt is going to give you a more transparent glaze than stains as it becomes incorporated into the melt whereas stains don't dissolve, they basically are suspended in the glaze melt. To answer your question about opacifiers, the Mason stains that have zirconium as part of the stain structure are 6364 Turquoise, 6374 Dark Turquoise, 6376 Robin's Egg and 6315 Zirconium Vanadium. I wouldn't let that be the deciding factor though. If you do try the cobalt you might want to add some manganese and/or iron oxide to it to tone down the intensity of the blue. You also will probably find that if you use more than just a fraction of a percent of cobalt that it will make your glaze more fluid, which actually might help get the effect you are after.

min, is zirconium going to make the glaze transparent or are you saying those colors wont be because of the  zirconium?

so i am on the wrong track completely thinking opacifiers cause lack of transparency.  it is melting that is important.

 

 

 

[Magnolia Mud Research]

15 minutes ago, oldlady said:

so i am on the wrong track completely thinking opacifiers cause lack of transparency. 

according to the Oxford English Dictionary:
the condition of lacking transparency or translucence; opaqueness.

My physics textbooks working definition:
opacity means that the light is refracted back in all directions; the effect is the same as looking through window glass that has been sand blasted on at least one side; therefore, opacity does reduce transparency as I understand you are using the term; you want the viewer to see the clay body surface to be seen through a blue tint.  

LT
 

[Bill Kielb]

1 hour ago, oldlady said:

so i am on the wrong track completely thinking opacifiers cause lack of transparency.  it is melting that is important.

 

My sense - it will often come down to the percentage used. So things that are colored reflect that wavelength of light or blue things absorb other wavelengths and reflect predominately blue. So in your situation, regardless of the colorant you will include a percentage that reflects the right amount of blue along with the mix of colors being reflected by background of the clay to get the desired look. So for instance a bright background combined with a Very small percentage of an intense darker color will often end by eye just the right tone. The background light escaping dilutes the tone of the colorant used because of the small percentage used.

Opacifiers definitely cause less transparency but so does more colorant as the light you can see is more and more a function of the colorant. If it’s all white, then that is the color seen. If it’s a tiny bit of all white then you will see that with a mix of colors from the background.

Hopefully that makes some sense.

[Bill Kielb]

3 hours ago, Hulk said:

Over white stoneware, if not too thick this blue is fairly "clear"...let me know if you want the recipe.

 

Nice bright colors! I would love to know the colorants and percentage.

[Callie Beller Diesel]

@oldlady, I’m using a transparent blue glaze over a thick white slip in that image. The colour isn’t in the slip.

So, opacifiers. They all work a little bit differently, which is why you get different qualities to your white glazes when you use different ones. You can get interesting things to happen when you mix your opacifiers, but by themselves, they usually work like this:

Tin is interesting, because it melts into the glaze. In small quantities, it can actually act as a fining agent in some clear glazes and cone 10 celadons. It acts as a flux, so micro bubbles can escape more easily. That’s why you need so much of it to get a fully opacified glaze. There’s excess tin that hasn’t reacted with the other glaze ingredients, and is just hanging around. It’s why it also can have a softer effect with more visual depth.

Zircopax is pretty unreactive, stays suspended in the glaze melt and that’s what makes you not be able to see through it. It is refractory in larger quantities. It can stiffen the melt, meaning other ingredients don’t have as much ability to move around and react with each other when they’re in a melted state. It gives more of a flat, toilet bowl white when it’s by itself.

Titanium melts, but makes a tiny crystalline structure that you can’t see through. Which is why it will also cause glazes to variegate.

Tin and titanium are both more reactive in glazes than Zircopax. When Mason wants a colour to pop, sometimes it helps to add a white background, hence the addition of small quantities of Zircopax (or another zirconium based structure) to their stains. They want the whitening effect, but they want to limit the number of things that will react with other glaze ingredients that might change the colour response. 

It can also make glazes made with mason stains look a little flat if you use too much stain. If you use smaller quantities of stain and make sure your glaze is well melted or a fluid base, you can still get translucent, pooling effects.  

If you want a really nice soft blue with purplish undertones, make sure your base recipe has lots of calcium to make the cobalt glow like that. This will hold true for both cobalt by itself, and mason stains made with cobalt.

[Min]

1 hour ago, oldlady said:

min, is zirconium going to make the glaze transparent or are you saying those colors wont be because of the  zirconium?

so i am on the wrong track completely thinking opacifiers cause lack of transparency.  it is melting that is important.

All stains will produce colours less transparent than if you were to do the same colours using oxides. This is because the stains don't dissolve into the glaze the way the colouring oxides do. A cobalt stain is going to make a cobalt blue, using cobalt oxide or carbonate is also going to make cobalt blue and it's going to be more transparent or clearer than the stained version. I think it's a red herring worrying about the tiny amount of zirconium in the blue stains, even if you added 2% zirconium into the glaze it isn't enough to opacify it. In all likelihood you will be using 2% or less stain. In fact some stains like the cadmium inclusion stains are actually clearer with the addition of a little zircopax as it helps clear the bubbles.

 

 

 

[oldlady]

ok,  i am going to use robin's egg blue because it DOES have zirconium (which appears to have some mysterious advantage in keeping the color more transparent than other ingredients). 

to have just a hint of color and as much clarity as possible, i will try 1 %  and less.    fortunately, a new neighbor is a math magician, taught it in many schools to students of all ages.

thank you all for reminding me that there is always something new to learn about this wonderful artscience.

[Hulk]

Bill,

Found the recipe here Cone 6 Glaze Recipes | Great Mid Range Pottery Glazes (lakesidepottery.com)

 

It's been a favourite!

[Bill Kielb]

2 hours ago, Hulk said:

Bill,

Found the recipe here Cone 6 Glaze Recipes | Great Mid Range Pottery Glazes (lakesidepottery.com)

Thanks!!  Not sure CMC is a colorant though and I always laugh when things add up in an interesting fashion.  

Seriously, thank you!

[Hulk]

Aye

As found:

I'll say I moved the gum, cobalt and rutile to the add section on account o' plan to measure out all the others, partially hydrate, mix, then blend in the pre-hydrated gum, and colourants...

I'm guessing a typo on my part, the talc.

Have been firing to cone five this last year or so (with a long hold at -100F after peak temp), this blue has been coming out fine.
It looks quite a bit different over other clays - depicted above is Clay Planet's "Venus White"

[oldlady]

hulk, the blue mugs are gorgeous.    it is a really beautiful blue.   i will use it some day as a bowl exterior.   but, i think i will have to have my math expert neighbor figure out how to do a total of 100.

[Hulk]

As published*, the parts total 100 (I'm off by a bit in my transposition to GlazeMaster - over a tenth for the talc, the rest rounding differences).

I'm using this clear blue at about 1.42 specific gravity. From there, a tweaking session to adjust the "gel" behaviour - a small drib of Epsom Salt solution at a time, mix, wait, test, and so on** - helps me a lot! The colour will vary in relation to the film thickness.

Here, same blue over same clay; the carved band is red slip.

*credit Lakeside Pottery for the recipe! 

**per Tony Hansen's video and article on the subject. Adjusting thixotropy has been a big - huge - factor in making glazing fun. Practice definitely helps as well, also being happy with the results (even less unhappy is an improvement - Hulk Smash!).

[Piedmont Pottery]

This is an example of Mason 6374 at 8 g to 100 g transparent base.  Even at this level of stain there is still a fair amount of transparency.   Breaks nicely over texture, still shows fine underlying textures when thin.

[Hulk]

More Lakeside Clear Blue, from yesterday's glaze fire

White stoneware.
All three have some chatter marking (filled with glaze, wiped back and allowed to dry before dipping); the bowl has a band of red slip; the mug has some underglaze.

[Bill Kielb]

20 hours ago, Hulk said:

More Lakeside Clear Blue, from yesterday's glaze fire

White stoneware.
All three have some chatter marking (filled with glaze, wiped back and allowed to dry before dipping); the bowl has a band of red slip; the mug has some underglaze.

Interesting in that the melt seems different from the mugs above. The mugs appeared glossy in the picture, these seem more matte or satin in texture. 

[oldlady]

that is a pretty blue, Hulk, i wish it were the color i want.    tried the pale blue resulted from 2% robins egg in the clear glaze Min gave me.   also 2% vivid blue.   both colors were sieved through a 150 mesh screen, thanks Neil, and yet the finished tests still show dark blue specks here and there.     the color is very pale, almost like a white rather than blue.  the thick test looked more like a snowstorm than a sky blue.   so it is back to test, test, test and the new tests will be numbered 527 and up.   nobody ever told me i would test so much.

thanks, piedmont.  mason 6374 is very like the robins egg 6376,

 

[Hulk]

Bill, perhaps the lighting - they are about the same shiny. The gloss does diminish some over the red slip, however.

I'm liking this scrap glaze

...will replace with a higher res image later on.

[Bill Kielb]

1 hour ago, Hulk said:

I'm liking this scrap glaze

...will replace with a higher res image later on.

Very nice IMO. I really like the color and finish. Nice rim line!