HCSM 1 + 2 White?

[Katie Piro]

I love HCSM 1 + 2 from John Britt's Mastering Cone 6 but I need a white semi-matte glaze. Has anyone had any luck adding zircopax to these glazes to make them opaque and white? I did some searching and couldn't find anything. Would love some feedback from the hive mind before I jump (more like fall) headfirst into testing mode. Thanks bunches. 

[Sorcery]

I recently took this to 9 and it got glossy.

https://digitalfire.com/recipe/g2934

Tony writes instructions on how to make it semi-matte at 6.

Sorce

[Bill Kielb]

1 hour ago, Katie Piro said:

I love HCSM 1 + 2 from John Britt's Mastering Cone 6 but I need a white semi-matte glaze

Generally it’s doable post the recipe, my Britt book is buried somewhere. Generally for a true matte you can start with getting this in a favorable si:al ratio which often saves a bunch of effort and not having to rely on slow cooling.

No guarantees but worth a look for sure.

[Katie Piro]

2 hours ago, Bill Kielb said:

Generally it’s doable post the recipe, my Britt book is buried somewhere. Generally for a true matte you can start with getting this in a favorable si:al ratio which often saves a bunch of effort and not having to rely on slow cooling.

No guarantees but worth a look for sure.

 

HCSM 1 Recipe: 

Kaolin  30

Wollastonite  29

Ferro Frit 3195  20

Silica  17

Nepheline Syenite  4

 

HCSM 2 Recipe:

Koalin   28

Wollastonite  28

Frit 3195  23

Silica  17

Nepheline Syenite  4

 

I'm really looking to make one of these specific glazes white since they are the foundation for many other glazes I make and I want to keep the variety of materials I buy (and need to store) to a minimum. Thanks!

 

 

[Min]

@Katie Piro, I've tested the High Calcium Satin Matte 1 base with 12 zircopax plus 2.5 tin oxide. It's a lovely white and still a semi matte with these additions. It does bump up the silica level (from the zircopax) but I found it still matte enough for me. I was using it over a white clay, I don't know what colour your clay is but will need higher opacifier levels over darker firing claybodies. I found it did slightly cutlery mark. If you also find it cutlery marks then do a line blend of the semi matte glaze plus a clear glaze, both with the same levels of opacifiers. There should be a point where the cutlery marking stops without the glaze becoming too glossy.

[Bill Kielb]

On 1/15/2021 at 10:34 AM, Katie Piro said:

I'm really looking to make one of these specific glazes white since they are the foundation for many other glazes I make and I want to keep the variety of materials I buy (and need to store) to a minimum. Thanks!

 

As Min said above, adding colorants would be the way to make this white. So white would be zircopax, Tin, titanium or a mixture of same as well as mason stains. With respect to these glazes generally slowly removing silica will turn them matte so you can try that in a line blend.
The personal problem I have with these recipes is they have very low flux ratios 0.1: 0.9 and  relatively high boron amounts for cone 6. My foundation glazes or base glazes if you will sport flux ratios in the range of 0.2:0.8 to 0.3:0.7 for durability reasons. While not a perfect indicator, this range is generally most durable and outside of it tend to be less than ideal.

So an easy thing to try would be simply progressively decreasing silica till you got the desired matte look. And adding colorants to get the desired white. For an idea of color you could search www.glazy.org for white glazes and get a sense of how much colorant and what compositions you likely prefer. Just sort by white then note the pictures and amounts of colorant to produce the shades you like. This can give you a good starting point to test your own glaze colorant additions from.

As far as this being a base glaze, for me personally it has compositional issues that I stay away from for potential durability reasons.

 

 

[Min]

14 minutes ago, Bill Kielb said:

The personal problem I have with these recipes is they have very low flux ratios 0.1: 0.9 and  relatively high boron amounts for cone 6. My foundation glazes or base glazes if you will sport flux ratios in the range of 0.2:0.8 to 0.3:0.7 for durability reasons.

High calcium matte glazes like the Hesselberth and Roy High Calcium Satin Matte glazes are supersaturated with calcium. During cooling the calcium forms microcrystalline structures (with some of the silica and alumina). Given that the flux ratio of this glaze is 0.1:0.9 using calculations this shouldn't be a durable glaze but in practice it is. Since some of the calcium is precipitating out of the glaze to form the microcrystalline matte surface I question whether using calc alone is enough to judge whether a microcrystalline glaze such as this one will be durable. My thought is the calculated "ideal" flux ratio of 0.2:0.8 - 0.3:0.7 is valid for gloss glazes where all elements are incorporated into the glassy matrix but not for microcrystalline glazes. Same principal behind why trying to calc the COE of claybodies using calculation figures isn't valid, crystallized solid mass as opposed to a gloss glaze where each element is fully incorporated into the glaze matrix.

[Bill Kielb]

26 minutes ago, Min said:

My thought is the calculated "ideal" flux ratio of 0.2:0.8 - 0.3:0.

Yeah, just a personal thing really, else I would need tested results. It generally is not worth my time to test and slow cooling adds another potential for varying results. I really don’t have time to be testing  combinations and  testing with reasonable confidence  in itself takes lots of time..

For me, I always feel I can create acceptable aesthetic results in known regions fairly easily so making it a base glaze is personally not in the cards. I also end up feeling the excess boron becomes a raw material waster but again all personal preference stuff not necessarily how others view it.

[Min]

I feel one of the most important advances to electric kiln firing is the practice of slow cooling. Since we are talking about one of Roy and Hesselberth's glazes and slow cooling vs rapid cooling an image taken from their FAQ page below. Same glaze on all 4, Variegated Slate Blue (which uses the High Calcium Satin Matte base 1) only difference is the cooling schedule.

Link to article the test tiles taken from here.

3 hours ago, Bill Kielb said:

and slow cooling adds another potential for varying results

Yes! That's what is so wonderful about it! In addition to creating wonderful matte glazes slow cooling is beneficial for phase separation in other glazes also.

[neilestrick]

I don't see slow cooling as being any different than anything else we do with firing schedules/methods. We alter firing speeds, add holds to increase melt, do reduction to change the look of the clay and glazes, etc. How is slowing down the cooling cycle any different? Plus cooling rates depend entirely on  the size of your kiln. There is no 'standard' cooling rate. In my big kiln it's 34 hours until I can unload. In my smallest kiln it's 5 hours. Which one is correct? By choosing my cooling rate I can get exactly what I want from my glazes. Adjusting a glaze for the cooling cycle is no different than adjusting it for the heating schedule.

[Bill Kielb]

1 hour ago, Min said:

Yes! That's what is so wonderful about it! In addition to creating wonderful matte glazes slow cooling is beneficial for phase separation in other glazes also.

All good actually. I wonder which in the pictures is more durable? Time to  test them all? Is 0.1:0.9 ok or maybe 0.05:0.95 is the line.  The point is it’s a personal preference, I really don’t have time to test them all to see nor would they become a base glaze for me. As far as the variation, effect, ability to do it, favorability in electric kilns ......... I love it.

[Min]

@Katie Piro, hope we haven’t side tracked too much from your original question. Takeaway from the fast vs slow cooling part of the discussion is that both of the glazes you were asking about are going to react to a slow cool. Level of "matteness" can be altered if required for your purposes. I'ld suggest just using the program you already use for those glazes and add your opacifier(s). 

[Katie Piro]

On 1/16/2021 at 8:10 PM, Min said:

@Katie Piro, hope we haven’t side tracked too much from your original question. Takeaway from the fast vs slow cooling part of the discussion is that both of the glazes you were asking about are going to react to a slow cool. Level of "matteness" can be altered if required for your purposes. I'ld suggest just using the program you already use for those glazes and add your opacifier(s). 

Thank you @Min, @Bill Kielb and @neilestrick! This has given me a lot of information. I wanted to stick with HCSM as a base because I LOVE Variegated Slate Blue, Spearmint, Bone, etc... And since I'm a one woman studio I need to keep the amount of different recipes I use to a minimum so I'm not wasting money on materials. I do love playing with the cooling schedule as well. Especially VSB which I sometimes fast cool if I want some glossy pieces in the mix. Thanks again! On to testing!