Laguna Frost ^6 users (glaze fit content)

[Morgan]

Aloha all,

So I use standard 365 primarily (which I am just in love with and think its one of the best) but it *would* be way more cost effective for me to use Frost $/lb since I can get it very reasonable in bulk from laguna to HI. Anyway, I have been putting it off and finally got around to getting a few bags and threw about 20 mugs with it. I have zero problems that a lot do with Frost, s cracks, attachments etc, that said I was very very shocked when I opened the kiln today and just about every piece I made in Frost had some form of crazing. Strange crazing, like a single almost stress looking crack down the side and others just normal crazing. What is strange to me is I purposefully glazed each piece with intent to test my glaze fits with it. I have an absurd amount of glazes that I am trying to hone in but that is another topic for another day. 

I guess my question and bewilderment is the majority of these glazes are tried and true super stable glazes and they still crazed, in fact a lot of these glazes I have never even heard of crazing on any clay bodies ever.  I did not expect every glaze to fit but was not anticipating every single glaze to have fit issues. 

I fire a slightly modified version of the digital fire drop/soak to a fairly perfect cone 6 bend and a natural cool. I let the kiln cool to well under 200 degrees and bisque fire slow to ^04. Really annoyed with it because as much as I prefer to throw 365, I have to admit the glazes look incredible on Frost, if not better, crazing aside. 

PS - If anyone knows any secret bulk freight for standard clay on the west coast that I do not know about I would die to know  

Mahalo!

Edited February 12, 2023 by Morgan

[Min]

Laguna gives COE figures for their claybodies, I realize they probably are not super accurate but they would probably be okay to look at for a ballpark range. Frost is posted at 6.99 which is really high compared to most of their claybodies which in theory should mean it does not require a low COE glaze. Also, the ingredients used to make it are minimal, halloysite, nepheline syenite, silica and bentonite. I don't recall reading anything lately that said those materials have had any major chemical changes.

Could you post a picture of one of the mugs with the "Strange crazing, like a single almost stress looking crack down the side..." and the glaze recipes you used on those. And then a recipe for one of the glazes that had regular crazing. 

Have you contacted Laguna with the batch number and asked them about the issues and if there have been any changes to the claybody? I'ld send them some photos of the cracks and crazing along with corresponding recipes also and see what they have to say.

[Morgan]

Sorry, disregard the "strange" comment, this morning every piece ended up crazing, nothing strange, just normal crazing, apologies for that confusing comment. This was 15 different glazes I tested which makes me think something is up with with the batch or something I am doing Frost does not like. Maybe my natural cool is too fast? I can list out every glaze I used if that helps but a few that come to mind:

Studio White
VC Soft satin glossy white
MCG1
John Brits Floating Blue 
Midnight Surf
Old Forge Sunset
Opal
Pinnel Stony Matte
Heath Ivory
Variegated Slate Blue
 

I will contact Laguna tomorrow and ask.

[Callie Beller Diesel]

Crazing has very little to do with your cool down rate. If you slow your cool and it appears to get rid of a crazing problem, you’ve likely only caused a crazing delay. A shock test will still bring it out. Crazing is caused by COE values that differ too greatly between clay and glaze. If this is your first test of using Frost instead of the Standard 365 clay and all your usual glazes have crazed, that just means the 2 clays have different COE’s. That’s not unusual at all. 

If you want to keep using the same glazes, you’ll have to adjust them all to compensate. If the crazing is slow to emerge and the crack pattern is a larger one rather than a covering of fine lines, chances are the glazes won’t need a lot of adjusting. That which bodes well for keeping the character of the glazes intact. It’ll be a little bit of work with a test sieve to hone in 10 glazes, but it’s doable. 

If you’re going to use glaze software to help narrow the project down, some notes about comparing COE values:

1) Using calculated COE values won’t eliminate physical testing, but it’ll cut down the work and materials used. 

2) COE values aren’t absolute numbers. They’re only a snapshot of a measurement taken under a very specific set of circumstances. If you change the circumstances, you get a different value. They’re good if you’re adjusting a glaze without adding or removing any ingredients, only changing quantities. Also worth noting that because of this, different glaze softwares use slightly different COE values in their source tables. If you’re looking at a clay manufacturer’s suggested COE range for glazes, make sure you’re using the same software they are. Many manufacturers have stopped offering these suggestions though, because they tend to cause more confusion than they help with.

3) You don’t want to match coe values of your glazes to your clay. That results in more glaze flaws. Knowing that you need to move your existing glaze COE values higher or lower is the important bit here. 

 

[Morgan]

I agree with everything you said and totally expected not all glazes to fit with a new clay body. Not that it is a barometer for anything but I have tried all these glazes with a dozen other porcelains (with similar COE) and other clay bodies with zero issues. Again, I know that does not mean much for Frost, but it just seems strange. That said, I find it pretty unusual that every single glaze (15!) did not play well with Frost. Especially given the glazes I tested which, are all for the most part, very much in a good range and known for their stability.  I feel like I would have heard or seen more people discussing Frost glaze fit issues, but maybe I have not been paying attention. Lastly, a lot of these glazes have years of pictures and reports on Frost with no issues for others poking around Glazy etc (Opal for example).

Anyway, I appreciate the comments, and agree, just still find it odd. Not a big deal, I will stick with works, but I would love to hear from folks that actually use Frost too to see if they are having/had such issues with such a broad spectrum of glazes that seemingly work fine for most people using the same clay body.

I appreciate the thoughtful and detailed response!

[Min]

Really sounds like there was an issue with the batch you got rather than a fit issue with all 15 of your glazes.

What I would do in your situation is make up some tests with increasing amounts of silica added to the body then try it with one or two glazes and see if it still crazes. I would add increments of 5% silica (200 mesh) and see if the crazing is reduced. I would dry out some unused clay (not trimming scraps) weigh out dry clay into four 100 gram batches and add 5% silica to the first, 10% to the second, 15% to the third and 20% to the fourth.  Add some water, slurry mix it then dry the slip on plaster until you can wedge it up. Make some test tiles with the clay, bisque as usual then try one of the glazes you know should fit the clay. Document every step with photos then see if the glaze crazing is reduced or worse. Send your findings to Laguna with an offer to send them a sample of the clay so they can test it themselves if you still aren't getting satisfactory help from them.

 

[Morgan]

Sorry for the late response Min. Ya, I am not sure I want to bother with the trouble of trying to get glazes to fit (at least not ALL of them ha), but seems like it almost has to be a batch issue. I have reached out to Laguna numerous times playing phone tag with no answer yet on the batch. I would like it to work out, but if it does not it is not the end of the world. 

I touched on it above but does anyone have any suggestions on how to try and find a better freight option for a few tons (however much can fit on say a palette) standard clay? Especially given that there are no distributers west of basically Kentucky that I can find. The quotes I get from them direct are astronomical compared to Laguna which makes sense but I feel there has to be some sort of option to at least look into. 

Thanks all!

[Mark C.]

One note about frost at least in the high fire version is it glassifies . This may have been the southern frost  from NZ where  thius started from. (I hope i'm not mixing it up with another body?) So my  guess is it really  really tight. The other thing is that it does not mix with other bodies (as in the scraps wedged together or a slurry) It does not play well with others I like to say.

All the potters I know in Hawaii use laguna products at least on Molokia and the Big Island due to better frieght rates.They are also all cone 10 potters  One does cone 10 electric crystalline glazes only.

You could also check on Clay Planet bodies in the SF Bay area as thats a bit closer than east of the Mississippi .They make good bodies as well. Although mucjh smaller that Laguna 

Another option is Tacoma art center clays or Seattle Pottery clay bodies. Also much smaller than Laguna

My guess is Laguna has something that will work for you

Edited March 6, 2023 by Mark C.

[Min]

12 hours ago, Morgan said:

I am not sure I want to bother with the trouble of trying to get glazes to fit...

My thinking was if you could demonstrate you got a bad batch then it might be worth trying again. Adding silica to the body could very well decrease or stop the glazes from crazing. If you showed Laguna this then they should replace your clay.

Mark brought up a good option with Tacoma Art Center or Seattle Pottery Supply, they both have their own version of a NZ porcelain. I've used the one from Tacoma, it's a nice claybody to work with and very white. Haven't tried the one from SPS.

[Mark C.]

Shipping will be your biggest issue to Kauai. Is there a clay supplier again in Honolulu .?The last one retired and i have not heard aboud a new one.

[Morgan]

There is a laguna distributer on the big island but they only carry a few bodies and the porcelain they carry is Hagi which I really did not like.

Min I will actually try that, good call.

[Mark C.]

2 hours ago, Morgan said:

There is a laguna distributer on the big island but they only carry a few bodies and the porcelain they carry is Hagi which I really did not like.

Min I will actually try that, good call.

Once you find your choosen body you could have them order it for you drop shipping by barge to Kauai via Young Brothers via Honolulu 

[Morgan]

2 hours ago, Mark C. said:

Once you find your choosen body you could have them order it for you drop shipping by barge to Kauai via Young Brothers via Honolulu 

That is what I was thinking...