Low specific gravity but THICK!

[Callie Beller Diesel]

@Pir Physical mixing doesn’t determine whether a glaze is flocculated or not.

Pinnell gives a good non technical description that gives a useful mental image of what’s going on. I think the point it’s failing you is how he’s describing the particles as either repelling or being attracted to each other like magnets in space. It’s not the particles that are repelling each other, it’s the fluid they’re suspended in that’s doing the work.

Remember this whole thread started with a glaze that was too gelled or flocculated. That  was affecting application, which in turn was probably affecting how the glaze turned out. Solubles leach out of certain materials (or can be added on purpose) to make the glaze particles hang out together more in the bucket, and that makes the glaze go on in that “fluffier” house of cards way.

Leach 4321 has the opposite properties in the bucket as the glaze that started this thread. It has nothing particularly soluble in it, unless you’re using Neph Sye instead of feldspar. Nothing’s slowly dissolving out of the dry materials that would change how they stay floating over time. Because this glaze has enough clay in it, it can stay suspended well enough for dipping and you can get a reasonable enough application if it’s just well mixed. But because it dries slowly though, it shows every drip mark and application imperfection after it’s fired, unless you feel like scraping it all smooth like Florian Gadsby does. (No thanks.) So unless you add something to the bucket like epsom salt solution or even a little vinegar, it’ll still hard pan if you leave the bucket undisturbed for a while. 
 

[Pir]

18 hours ago, Callie Beller Diesel said:

But because it dries slowly though, it shows every drip mark and application imperfection after it’s fired, unless you feel like scraping it all smooth like Florian Gadsby does. (No thanks.) So unless you add something to the bucket like epsom salt solution or even a little vinegar, it’ll still hard pan if you leave the bucket undisturbed for a while. 

Thanks Callie, I had to sleep on this, and this morning I've been pouring over Digitalfire articles (again)!

Anyway, yes, I will floc that 4321 with some epsom salt solution.

Interesting with Hansen describing how he gets a lower SG (1.43-1.45) and then flocculates. He uses epsom salt powder, which I haven't seen yet; I also haven't tried vinegar yet.

P

[PeterH]

2 minutes ago, Pir said:

Interesting with Hansen describing how he gets a lower SG (1.43-1.45) and then flocculates. He uses epsom salt powder, which I haven't seen yet; I also haven't tried vinegar yet.

Interesting, but I don't think you need to buy it.
Crushing Epsom Salts https://digitalfire.com/picture/2119

... but I cannot see how it can take effect as quickly as the saturated epsom salt solution many recommend.

[Pir]

51 minutes ago, PeterH said:

Interesting, but I don't think you need to buy it.
Crushing Epsom Salts https://digitalfire.com/picture/2119

... but I cannot see how it can take effect as quickly as the saturated epsom salt solution many recommend.

I did notice that he emphasized "stirring vigorously" when he mentioned adding powdered epsom salts! Maybe it's simply to avoid additional liquid.

 

[Pir]

So, I tried to rescue a bad glaze via the Hansen/Digitalfire method we've been discussing on this thread. I've used epsom salts before, successfully (i.e., it noticeably and quickly gels), but last night I tried it in a simple white mat recipe (which applies just awfully)--

neph sye 35 / dolomite 20 / whiting 5 / EPK 20 / silica 20

--but the epsom salts did NOTHING! I brought the glaze down to 1.44 or 1.45. I used a concentrated solution; I made another batch to be sure it was super concentrated; I added a liquid bentonite (my suspicion was that more clay might be needed?); and then I even added vinegar (last ditch effort), and nothing got that damn glaze any better:  it remained thin on the finger; it dripped all over the test tiles; it kept spinning in the bucket; it never bounced back, reflecting thixotropy. And, slow dry.

The glaze has been sitting for 5  or 6 months, I'd guess; and I did dump off the yellowish water from the top (soluble stuff from the neph sye?) and added new. (Hansen's got me wondering about my tap water now!) It also may be the case that some months back I tried adding Ep salt, too.  

Anyway, if those factors don't apply, I wonder what's preventing this glaze from playing nicely? 

Pir

[Min]

I have a cone 10 glaze with just under 65% nepheline, some dolomite and zircopax plus just under 5% ball clay. It sinks like a stone in no time, however I've gone a year between uses of it and it still stays suspended with some MAGMA. This stuff will float rocks as @Mark C. often says. 

The 5 whiting aka calcium carb will mess with the vinegar. Carbonates + vinegar = CO2 gas, might be enough to negate the effects of the vinegar. Another thing you can try is calcium chloride instead of epsom salts. (it's sold as ice melt)

Edited November 15, 2022 by Min

[Kelly in AK]

Something I just remembered seeing years ago was Tom Coleman in a workshop using muriatic acid to suspend glazes. I can’t remember the reason, but he preferred it to Epsom salts. Fizzed up when he put it in. Not something I’d try casually, but maybe worth researching. 

[Dick White]

Flocculants are mildly acidic. Deflocculants, except Darvan, are mildly alkaline.  So... muriatic acid, and common white vinegar are clearly acids, but epsom salts (magnesium sulfate), and calcium chloride (swimming pool calcium hardness increaser) are also acidic, and all the above serve well as flocculants. The dry chems (epsom salts and calcium chloride) must be dissolved in the appropriate amount of water to achieve a saturated solution, but the muriatic and vinegar are already liquid. The muriatic acid is already mixed to a fairly strong solution, so only a few drops are needed and it will create a reaction as it hits the water, hence the fizzing. 

[Pir]

15 hours ago, Min said:

it still stays suspended with some MAGMA.

Wait, what's MAGMA?

[Pir]

14 hours ago, Kelly in AK said:

Something I just remembered seeing years ago was Tom Coleman in a workshop using muriatic acid to suspend glazes. I can’t remember the reason, but he preferred it to Epsom salts. Fizzed up when he put it in. Not something I’d try casually, but maybe worth researching. 

I've never heard of it, but I see it's Hydrochloric Acid (HCl).

[Pir]

14 hours ago, Dick White said:

Flocculants are mildly acidic. Deflocculants, except Darvan, are mildly alkaline.  So... muriatic acid, and common white vinegar are clearly acids, but epsom salts (magnesium sulfate), and calcium chloride (swimming pool calcium hardness increaser) are also acidic, and all the above serve well as flocculants. The dry chems (epsom salts and calcium chloride) must be dissolved in the appropriate amount of water to achieve a saturated solution, but the muriatic and vinegar are already liquid. The muriatic acid is already mixed to a fairly strong solution, so only a few drops are needed and it will create a reaction as it hits the water, hence the fizzing. 

Thanks, Dick. I've never used it. Oh, and the vinegar I used was apple cider... I'm sure it's still acidic, but probably not great if the "mother" gets into the glaze...

[Pir]

15 hours ago, Min said:

I have a cone 10 glaze with just under 65% nepheline, some dolomite and zircopax plus just under 5% ball clay. It sinks like a stone in no time, however I've gone a year between uses of it and it still stays suspended with some MAGMA. This stuff will float rocks as @Mark C. often says. 

The 5 whiting aka calcium carb will mess with the vinegar. Carbonates + vinegar = CO2 gas, might be enough to negate the effects of the vinegar. Another thing you can try is calcium chloride instead of epsom salts. (it's sold as ice melt)

I'm beginning to wonder if glazes with neph sye are a bit more reluctant to gel with Epsom salts. Thanks for the info on the vinegar and calcium/whiting.

I played with 7 or 8 glazes last night, testing them on test tiles and fingers to watch dripping, thinning them, adding Epsom solution, testing more and watching the finger tests get better and better. Sometimes they got too gelled, so I added a drip of Darvan or water, etc. Watching the glazes spin in the buckets, they went from watery and "endless" spinning, to gelled and coming to a firm stop after 2-3 second--however, that bounce back indicating thixotropy was sometimes elusive, or so subtle as to be hard to detect. Anyway, think I'm getting the hang of it. (Hope my fired results will corroborate this feeling.)

I have a few lovely heavy-Alberta slip glazes (85%) that have always seemed to apply pretty well as they are, although maybe I'll try to thin and gel a few cups just to see. Hansen/Digitalfire and even the Alberta Slip website seem confident that even 40 or 50% Alberta slip will crack on drying (and or crawl, I think), and therefore one needs a "roasted" or calcined portion, but luckily this hasn't been my experience, though I wonder why...

 

[Pir]

On 10/21/2022 at 4:52 PM, Callie Beller Diesel said:

The reason you got cracking after that is more likely because of the clay content. Combined, that’s 20%, which can be a big high. Because you can’t really remove clay without affecting silica or alumina levels, you could either just use 20% epk (shrinks less when it dries than ball clay), or calcine half of the clay before adding it to your recipe.  

On 10/24/2022 at 5:53 PM, Min said:

It's just fine tuning the math, round up or down by the hundredths and you can get the ratios exact. I don't know to which decimal point Glazy will go to. Probably not significant.

Hi Callie and Min, regarding that satin black (John Britt's x10 in his book) that was cracking upon drying (and after firing showed the crack lines or even crawled), I wanted to say I tried both your advice: I recalculated and reduced the ball clay/increased the EPK. Haven't fired yet, but test pieces did NOT crack!

Then I thinned the original, problematic batch, and gelled with Epsom salts: test tiles showed only hairline cracking where thicker. So, we'll see how they fire up.

Thanks again!

Pir

[Min]

2 hours ago, Pir said:

Wait, what's MAGMA?

https://www.brackers.com/wp-content/uploads/2010/11/magmainfo.pdf

https://www.brackers.com/magma-miracle-anti-gravity-multipurpose-additive/

If your glaze slurry can't be dried slowly then don't use it, otherwise it is brilliant stuff. If you try it do add the tiny bit of copper as the instructions indicate (if the glaze doesn't have any) as this is an organic product and will rot otherwise. Doesn't work quickly like vinegar or epsom salts etc, need to leave the glaze alone for about 8 hours for it to work.

 

[Pir]

15 minutes ago, Min said:

https://www.brackers.com/wp-content/uploads/2010/11/magmainfo.pdf

https://www.brackers.com/magma-miracle-anti-gravity-multipurpose-additive/

Interesting! Will have to try... eventually.