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A Few Glaze Problems, Drying To Slow... Not Enough Suspension.


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#1 High Bridge Pottery

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Posted 21 February 2014 - 04:12 PM

Ok, well I had a few questions but don't seem to have put one recipe into my glaze database or I am just too tired to decipher my own work.

 

One recipe I do have goes as follows.

 

Soda Feldspar 51

Potash Feldspar 36.7

Quartz 25.5

Dolomite White 2

Whiting 18.9

China clay 2.6

Ball Clay 9.2

Iron Oxide 11

 

Nice looking glaze, but after 3 hours it is nearly rock solid on the bottom. I have bentonite, so can I add this to my glaze if I mix it with water first? How much would be a good amount for this recipe?

 

I used to put some plaster of paris in my glazes to aid suspension and it seems to work quite well. Anybody have an opinion on which one they prefer or their favorite suspension agent?

 

 

 

The other recipe I have just takes forever to dry!! I am talking about 5 minutes a pot before I can handle it :( Sorry I can't post the recipe but I will add it when I quickly pop into the studio later on and can find my glaze book. It is just hard to glaze them and not touch any glazed bit until it is dry.

 

Edit : Recipe

Soda Feldspar 10

Cornish Stone 30

Quartz 10

Dolomite White 10.5

Whiting 10.5

China Clay 25

Tin Oxide 2.7

Zinc Oxide 4



#2 mregecko

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Posted 21 February 2014 - 04:40 PM

That.... Does not add up to 100.  ;)

 

But just doing some mental comparisons, way more feldspathic components than clays. It will definitely tend to settle/pan out.

 

From what I've read & the few glazes I've made, adding about something bentonite will help. 4-5% is a good starting point. It's better to mix it in with some dry components to avoid clumping, but if you can't then mixing it with water is definitely the way to go.

 

John Britt has a great Youtube on this that is posted around here pretty frequently:

It addresses the use of bentonite, and the issue of glazes that take a long time to dry.



#3 High Bridge Pottery

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Posted 21 February 2014 - 06:26 PM

Indeed it doesn't, but is it that important? I have just started to use this recipe, just found it online... somewhere.

 

Thanks for the video, will give it a watch later.

 

Edited the post so it now has all recipes.



#4 neilestrick

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Posted 21 February 2014 - 07:41 PM

Add 2-3% bentonite and 0.5-1% epsom salts.


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#5 clay lover

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Posted 22 February 2014 - 04:25 PM

Is her 2nd glaze OVER flocculated?   Why won't it dry and why add epsom salts to that problem?  I understand adding ES to the hard paned glaze.b



#6 Benzine

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Posted 22 February 2014 - 05:01 PM

Is her 2nd glaze OVER flocculated?   Why won't it dry and why add epsom salts to that problem?  I understand adding ES to the hard paned glaze.b


Yeah, going by what John says in the video, if a glaze is taking a while to dry, it is flocculated. His solution was the Darvan 811, or sodium silicate.

I am not an expert, just parroting what I heard.
"Anything worth believing, is worth questioning"

#7 neilestrick

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Posted 22 February 2014 - 08:06 PM

The reason this glaze is settling badly is because it's low in clay. Bentonote is needed to keep it suspended, and the eposom salts will help everuthing stick to the bentonite.

The reason the other glaze is drying slowly is probably because it's high in clay. Clay holds onto water more than other glaze ingredients. I've got a couple glazes like that too. Just gotta be patient, or a little deflocculating, but be careful you don't go too far or it'll settle out.
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#8 High Bridge Pottery

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Posted 22 February 2014 - 10:01 PM

Is her 2nd glaze OVER flocculated?   Why won't it dry and why add epsom salts to that problem?  I understand adding ES to the hard paned glaze.b

 

That advice was posted before I had edited the second recipe into the topic. Thanks for the tips, I think I will just have to be patient or try and substitute out the china clay for something else.. Going to add some bentonite and epsom salts (if I can find epsom salts) to my glaze tomorrow,

 

Hey, I never knew I was a woman  :lol: maybe that is where I am going wrong



#9 Chilly

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Posted 23 February 2014 - 02:59 AM

 

 epsom salts (if I can find epsom salts)

 

Co-op and Lloyds pharmacys didn't stock ES, but local independant did, when I tried last week.


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#10 Babs

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Posted 23 February 2014 - 03:03 AM

 

 

 epsom salts (if I can find epsom salts)

 

Co-op and Lloyds pharmacys didn't stock ES, but local independant did, when I tried last week.

 

Often in supermarkets   magnesium sulphate, bakingtuff or among the soaps, shampoos etc, a soak for sore muscles as well as a laxative I believe.



#11 High Bridge Pottery

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Posted 23 February 2014 - 07:24 AM

Found 200g Epsom Salts in Boots for £1.49 :D

 

Time to relieve my glaze of occasional constipation, only problem is I cant remember if I did 20x the recipe or 30x to fill the bucket. I will assume 20 and then see how that works out, better to let myself add more if need be.



#12 Roberta12

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Posted 23 February 2014 - 10:50 AM

Yep, bentonite and Epsom salts....that's the ticket.  Many recipes will have 2 or 3% bentonite already added in.  But I have added it to glazes that really settle.  I am pretty sure I added Epsom salts to my bucket o slip also. 

 

Roberta



#13 Chantay

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Posted 23 February 2014 - 12:11 PM

I just posted about this a few days ago with another John Britt video:

 

http://community.cer...ng-your-glazes/

 

Video: 

 

 


- chantay

#14 Chilly

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Posted 24 February 2014 - 04:48 PM

Found 200g Epsom Salts in Boots for £1.49 :D

 

 

£2.99 for 1.5 KG in local independant.  Pleased I didn't go to town and pay for parking to go to Boots !


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#15 High Bridge Pottery

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Posted 24 February 2014 - 07:24 PM

Damn, I thought it was a good deal at the time  :lol: Still, I only needed the tiniest bit for my glaze. Neil's advice worked a treat and the glaze is now so much better.



#16 Babs

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Posted 24 February 2014 - 08:53 PM

It's the freight that gets you , all that way up , nearly in Scotland! Prob. don't have parking fees up there!



#17 High Bridge Pottery

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Posted 24 February 2014 - 09:29 PM

I don't have to pay to park my feet  ;)



#18 Babs

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Posted 25 February 2014 - 05:38 PM

English your first language??



#19 DarrellVanDrooly

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Posted 02 March 2014 - 07:16 PM

I add a cocktail of cmc solution, epsom salts, bentonite, and glycerin to my glazes for suspension. Im not sure if there's a particular one of those that works the best, or if they work the best in a mix. 


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#20 DarrellVanDrooly

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Posted 02 March 2014 - 07:18 PM

For a 10,000g batch I add like 50g of bentonite, 1/2 cup of epsom salt solution, 1/4 cup of cmc solution, and maybe 3 tablespoons of glycerin.


Derek Von Drehle - Bearded Lady Studio

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