Transparent cone 6 grey glaze?

[Algoessailing]

I'm looking for a transparent  glaze recipe with a slight grey tint.  My goal is to be able to see darker underglaze beneath the glaze, .  I tried a couple glazes from glazy, but neither really worked (they grey color was derived from cobalt so it was spotty) .  I have considered mixing mason stains in very low percentages into a clear, but I don't know what kind of %'s to start with.  Or if there is a better route?  

[Joseph Fireborn]

Start with 0% and increase by .5-1% all the way until it isn't transparent anymore.

[Min]

2 hours ago, Algoessailing said:

they grey color was derived from cobalt so it was spotty

If you use cobalt oxide it can leave specks in the fired glaze, cobalt carbonate doesn't do this.

Gray is a tricky colour to get, stains are probably the easiest way to go. The glaze you use the stains in makes a difference to how they turn out, look at the Mason Reference chart for what the glaze requirements are.

[Callie Beller Diesel]

I will say that my most recent experiment on black underglaze involved 3% in a clear base, and it went quite solid. I’d be more inclined to start in increments of  .1% if you want a grey.

 

[Algoessailing]

13 hours ago, Min said:

If you use cobalt oxide it can leave specks in the fired glaze, cobalt carbonate doesn't do this.

That's good info, thank you.  I'll pay particular attention to how those two behave in my future glazes.

[Algoessailing]

10 hours ago, Callie Beller Diesel said:

I will say that my most recent experiment on black underglaze involved 3% in a clear base, and it went quite solid. I’d be more inclined to start in increments of  .1% if you want a grey.

That's where I was looking for some guidance from anyone who has tried it before.  My original schedule was for 0.5, 1 and 2% but I wasn't sure if that might be too much.  

[Joseph Fireborn]

Honestly the only way to get this right is to just test it. There isn't really a way to skip that hard work between. 

 

[Chilly]

On 3/11/2021 at 12:56 AM, Callie Beller Diesel said:

increments of  .1% if you want a grey.

Unless you have very accurate milligram scales, you could try dissolving/mixing with water/gum solution so you can use a syringe to add tiny amounts.

[Algoessailing]

I have only ever used black mason stain so I expected the grey to be just as potent: it is not.  My first testing:

Mason Stain 6530 Silver added to Standard Ceramics Clear Gloss 1125, Black is  Amoco velvet underglaze.  

#35 - 0.1%

#36 - 0.3%

#37 - 0.5%

#38 - 0.7%

At first it seemed like there was no difference, but there is, albeit slight.  

I'll post results of my next testing when completed.

[Algoessailing]

On 3/11/2021 at 9:00 AM, Joseph Fireborn said:

Honestly the only way to get this right is to just test it. There isn't really a way to skip that hard work between. 

 

I find that interesting on two accounts.  (1) I would be surprised if I was the first person to ever want a transparent grey glaze, someone surely has tried this before.  Though it may be a small chance that they are on this particular website.  (2) In my professional work, I do dilutions for lab testing on a daily basis, and we must guess what dilutions to make.  But, there is literature, and mathematics, that guide us as to which dilutions are beneficial.  EG the difference between an 8% and a 16% dilution is not significant enough mathematically to bother running both tests, so an 8% and  25% is selected instead.  I was hopeful that ceramics had similar guidelines.  

[Min]

I've used gray stains, Mason Pearl at 2 and 3% gives a nice soft gray. Mason Silver is just 10% Mason 6600 (Best Black) + 90% tin oxide. Both those gray stains are blended stains, both have been discontinued but you can find which stains and opacifiers they are blended from on Mason's Archived Formulas page here. Often the discontinued stains are still available at some suppliers, just not directly from Mason. I'll go see if I can dig out one of my old pots with the Pearl stain, I know I don't have any with the Silver left.

edit: found a tiny bowl with the Mason Pearl stain on the inside, this would be at 3%. It isn't transparent at 3% (due to the tin in the stain) but it is somewhat transparent at 2%. If you want a transparent gray look at the Archived Formulas I linked to and try the ones without tin. What colouring oxides are used as the colourants will make a difference as to the shade of gray as will the base glaze you use. Blue grays with cobalt, greenish grays with chrome. 

Mason Silver stain contains only 10% Best Black stain (the remaining 90% being tin) so even your sample with 0.7% stain will actually only have 0.07% Best Black which would account for a very minimal tint to your glaze. If you had used 0.7% of an all (or mostly)  blue cobalt stain to make a blue glaze (as an example) this would definitely have tinted the glaze a blue. It's for this reason this isn't a one size fits all approach to how much stain to use in addition to the base glaze composition.

 

[Joseph Fireborn]

4 hours ago, Algoessailing said:

I find that interesting on two accounts.  (1) I would be surprised if I was the first person to ever want a transparent grey glaze, someone surely has tried this before.  Though it may be a small chance that they are on this particular website.  (2) In my professional work, I do dilutions for lab testing on a daily basis, and we must guess what dilutions to make.  But, there is literature, and mathematics, that guide us as to which dilutions are beneficial.  EG the difference between an 8% and a 16% dilution is not significant enough mathematically to bother running both tests, so an 8% and  25% is selected instead.  I was hopeful that ceramics had similar guidelines.  

I am not disagreeing with you at all. I am sure plenty of people here have made a transparent grey glaze. You can search glazy for transparent grey glazes and find one pretty quick probably. 

The reason I was saying to test is because everyone's kiln fires slightly different, clay is different, glaze ingredients are different, and many more things which make it nearly impossible to just say okay here is a transparent grey glaze and it work perfectly. The quickest way to find a glaze that works for you is to just do the dirty work and test with a bunch of tiles super quick. You could do a line blend or a dry addition method to quickly find where your transparency lies and then fine tune it to your acceptance level with only a few firings.

The first thing I would do is find 5-10 transparent glazes on glazy or out of a book and fire them the way they come, do multiple dips, etc etc. Figure out which one does the best on your clay and your schedule. Then purchase a few different grey stains that you think you might like. Look for ones without opacifiers, such as tin oxide as everyone has said here already. 

Now that you have your base transparent glazes that fit your body well and you are happy with the surface and durability run some simple line blends. https://wiki.glazy.org/t/volumetric-blend-testing/109

After you run your line blend for the glazes  and have fired them you will have 30-40 tiles to look at and examine their transparency. Pick the ones you like the best and then you can finalize your range really quick to find the perfect transparency. 

In total this took probably 3 maybe 4 firings to dial it in, but you will know exactly what you want and have a range of transparency.

 

EDIT: I did a search and found this wonderful article that might help a good bit: https://wiki.glazy.org/t/grey-mid-fire-glazes/260

 

[oldlady]

al, pottery might not be something you will enjoy.   

[Algoessailing]

14 hours ago, Joseph Fireborn said:

The first thing I would do is find 5-10 transparent glazes on glazy or out of a book and fire them the way they come, do multiple dips, etc etc. Figure out which one does the best on your clay and your schedule. Then purchase a few different grey stains that you think you might like. Look for ones without opacifiers, such as tin oxide as everyone has said here already. 

 

 

Thank you for your detailed response.  I started my pursuit of this glaze by searching glazy.  There are two "transparent grey" or "transparent gray" glazes, one is brown and the other is clear.  Maybe there is a better way to find things on the glazy website than using the search?  but I wouldn't know what a transparent recipe looked like if it wasn't in the glaze name.  I searched through this site without any luck either.  The wiki page you linked brings up 11 grey stains, I have tried nine of those, including the cone 9 glaze (fired to cone 6 just to see what happens).  Two  of those I liked and made 20-30 different variations, though none were transparent.  That's when I posted  here looking for guidance as to if I should use stain or something else.  Based on the responses, I went to my local supplier (3 hour round trip) and purchased the mason stain they had labeled "grey" (which turned out to be 6530 silver) and did some testing (photo above, posted so if someone else searches for it.)  

How do you know which mason stains don't have opacifiers?  Their website only lists that for discontinued glazes.  

 

[Algoessailing]

18 hours ago, Min said:

It's for this reason this isn't a one size fits all approach to how much stain to use in addition to the base glaze composition.

That is a great color! Thank you for taking the time to dig it out and explain how the stain mixes work, as always, with your post, great info.  

 I am curious what I said to give the impression I was looking for a one size fits all?

[Algoessailing]

7 hours ago, oldlady said:

al, pottery might not be something you will enjoy.   

ha ha, yeah.  Just because I don't want to reinvent the wheel, doesn't mean I don't love wagons.  But I suppose time will tell, lol

[Joseph Fireborn]

Al,

In the post where you have tiles, it looks like the 38 tile is slightly darker than the previous ones. Maybe just keep increasing the stain %. I didn't realize you only went to .7%. That might not be enough, go all the way from 0% to like 5% doing like .5% at a time or something. Then FOR EXAMPLE once you get say transparency at 2.5% and nontransparency at 3.5% go back and fire tiles with 2.1, 2.2, 2.3, ..., 3.5% for example. This should give you the exact range you want for your transparency. 

I think you just didn't use enough stain. 

[dhPotter]

@Algoessailing

Searching for Clear will get you transparency glazes. Also look at digitalfire.com for clear glazes.

[Callie Beller Diesel]

Ah! I see what went wrong with the test tiles. For some reason I was reading the underglaze as a black glaze. 

Not all mason stains have the same strength, nor do they have the same colour response in different base glazes. If you had been using that very small quantity of black stain, the results may have been more pronounced. Grey stain is less saturated, so you need more of it to be more visible. Different fluxes in your base glaze and quantities of some of them will affect how intensely they work as well. Hence why some of this information seems pretty vague. The answer to almost anything in ceramics is “it depends,” because there’s usually more than a few ways to get a given result.

If you’re looking to see if a given stain has tin in it, pull up the MSDS sheet for it on the mason stain website. They won’t give proportions because that part’s proprietary, and there is a certain amount of “may contain” wording for the same reason.  They also have this Handy quick reference chart.

They won’t give intensity indications, because a lot of that depends on how you want your glaze or underglaze to turn out. As a general rule though, the pinks, most yellows, most reds and the greys are the persnickety ones, and may require more stain to get a more saturated result. Blues, greens, browns, blacks tend to be more robust and more saturated. There are exceptions on both sides.

[Min]

4 hours ago, Algoessailing said:

How do you know which mason stains don't have opacifiers?

All but 3 of the gray stains have been discontinued but can still be bought at many places. The discontinued stains are what Mason calls blended stains which are made from at least 1 stain + either an opacifier (zirconium or tin) or another stain or silica. 

Of the 3 gray stains still being produced Sage contains cobalt oxide and nickel oxide. Gun Metal contains cobalt oxide and nickel oxide also. These stains contain different amounts of those 2 oxides so they turn out differently. I've used both, Sage is a green gray and Gun Metal a blue gray. The third gray stain that is still produced, Taupe, contains alumina, chrome,  iron, silica and zirconium. This info can be found on the Mason website, just click on the colour and the info comes up. (Taupe is currently not showing but I had the info)

Screenshot below from the link I posted above of the archived blended gray stains, this contains far more grays. To find what's in the archived blended stains you have to look here. Top one in the screenshot is Pearl 6506. It's blended from 10% 2820 flux, 5% stain #6306, 10% stain #6600 plus 75% calcined tin. Going down the list you can see Silver also contains tin (90%) and Slate has 27% of it and Blue Gray contains 35% tin.This info isn't on the MSDS or the current Reference Guide.

Re base glaze, do have a look at the Reference Guide as to the base glaze requirements. Some stains have specific do's and don'ts as to what they should contain or firing range etc. For your Silver stain you won't find it on the Reference Guide but just look up the 6600 black stain it's made from and you can see it can be used as a body stain, fires to 2300F and the base glaze can contain zinc but doesn't have to.

[Algoessailing]

5 hours ago, Joseph Fireborn said:

go all the way from 0% to like 5% doing like .5%  once you get say transparency at 2.5% and nontransparency at 3.5% go back and fire tiles with 2.1, 2.2, 2.3, ..., 3.5% for example. 

This seems like the best approach at this point.   Thank you

[2Relaxed]

Late to the party but Campana Grey might be what you're looking for.