Deflocculated and Flocculated Glazes (Free Online Glaze Course Part 15 Lab)

[@artwork2201]

Hi John, Thanks for the video. Added 1/2 TBS epsom salt to three gallons glaze and it made a world of difference.

[@Radagast97]

John, I did some more research on the subject of flocculation and deflocculation. We were both right in some regards, but both our mechanisms were incorrect. A great discussion of this is found in Ceramic Science for the Potter - see Pgs 59 - 64. Apparently a really key aspect to flocculation/deflocculation is cation size. Large cations deflocculate, small flocculate. Na+ and K+ are large and deflocculate, Ca++, Mg++, and H+ (responsible for acidity) are smaller and flocculate. Has to do with the distances between the alumino-silicate plates of the clay and how the cations fit between them. Really fascinating stuff.

[@clayphoenix]

This is such a clear and concise explanation of a concept that has been so confusing to me. Thank you John! You helped me save a full 5 gallon bucket.

[@mamemckee2190]

John, I came back for this info again today and used it to resolve an issue with a commercial glaze we buy in dry bulk. I bought litmus paper and found it to be 10+ ph so .......magnesium sulfate. I'll find out in the morning if it worked but it looks promising after a few hours. With my studio glazes I know the ingredients making them easier to maintain. What ever it was I tried last time with this problem glaze, it made it settle out like concrete! Thanks for sharing glaze wisdom.

[@Wetherby10]

John, think you could put all this info onto a big poster for me to hang on the wall. I'd buy two! Great stuff. Best wishes for the holidays.

[@gallaghereva]

Great explanation and here yesterday I have been blaming the cracking in Bailey's red on our bone ash - that we had changed to natural bone ash and stopped using the synthetic. Our glaze was sitting around for quite a while so got flocculated. Thanks Eva Gallagher

[@MuditisPottery]

Thanks so much for this information John. You are so smart!! Now I know why my glaze was looking too thick and falling off... and.. I did add water to my glaze when it was too thick! So happy to get this information. Thanks again and Happy Holidays to you and your family! Sonja

[@yedrow]

Oh yea, I love your book. It is one that I draw from most and of the two that I most recommend to other potters.

[@keramatmemarmoshrefi2404]

Fantastic

[@jaimwah]

Big help, thanks from the uk.

[@debkayaker]

Great video - love your vids - short and sweet and to the point! Keep up the great work! Thanks!

[@yedrow]

Thank you for the great information, it's exactly what I've been looking for; a visual on the concepts. I have a question, why would the flocculated glaze not dry quickly? It sounded like you were saying that both effects in excess result in the slurry remaining wet on the bisque. I've read thought that because of the "card house" effect, a flocculated slurry will allow the water to enter the bisque faster.

[@johnbrittpottery]

Flocculation can cause crawling. Thought I talked about that in the video? Crazing is a Coefficient of Expansion issue and not related. Deflocculation can cause variations in glaze thickness and therefore affect the way the glaze looks.......

[@Jigatree]

Thank you :D Simple explanation and fixes. Going to try this out with my glazes. I have both over flocculated and deflocculate glazes.

[@cwalexlai]

John, thank you so much for sharing this information. It helped me to correct some of the problems!!

[@johnbrittpottery]

Glenn, No worries. I am not that sensitive. You probably know more about it than I do but....vinegar does flocculate and Red Devil lye will deflocculate. (I have recipes from Brian Ransom and they work great!) So I am not sure of the chemical ions language but adding bases deflocculate and adding acids or salts that act like acids -flocculate. When I get some time I will look it up in the Potters Dictionary (Hamer and Hamer) because they have an extensive discussion of it. I

[@SirenaAzulejaCeramica]

Thanks John!!! Hi from Colombia I have heard using epsom salts can damage the elements of an electric kiln… I think the amount in the final glazed pot should be very small and it doesn’t make a big damage as other salt glazes for instance … what do you think? Thank you always 🎉

[@johnbrittpottery]

Epsom salts won't damage kiln ...magnesium sulfate...VERY small amounts!

[@chuckgrunt100]

This video takes me back to my glaze chemistry class in college. Thanks for the quick review.

[@amcreative3784]

Definitely helpful .one was really thick altho probably tooany layers applied Thanks. Will record your advice in diary

[@DirtKickerPottery]

Hey John, Is it possible that these chemicals that assist in deflocculation and flocculation, could affect my glaze fit and/or final glaze results? Pin holes, crazing, crawling.. etc.

[@credenza1]

Very useful and informative. Thanks for the advice.

[@jillwazstudio]

Best explanation out there! Thank you!!!

[@joanlizscott]

Excellent info thanks I learnt a lot of really valuable stuff.

[@Radagast97]

I agree with what you say above, John, if it seemed I was contradicting you, I apologize. Why do you attribute flocculation to pH? Vinegar won't flocculate a glaze or slip, yet raises acidity, quicklime won't deflocculate but raises alkalinity. Adding group II metal ions (Ca++ or Mg++) will (due to charge cross-linking with the sl negative hydroxyl sites on the clay plate). Adding group I ions (Na+, K+) deflocculates by blocking said cross-linking. Your thoughts?

[@Evan-hw6mn]

This is a great video. I just started making my own glazes and they're turning to jelly after sitting for a week. Are they over flocculated?

[@johnbrittpottery]

If they have gerstley borate then that is a property of gerstley...it gels. So you can leave it as is. Just stir well before using. If not, then perhaps yes. You can get great help on the Facebook Group...Exploring Midrange Glazes Together with John Britts book

[@Radagast97]

Perhaps there's a second mechanism at work I wasn't aware of. I'd never noticed vinegar flocculating clay slurries (I use it when "seasoning" clay) but could easily have just missed it.

[@DreamsOfTheMind-video]

Great explanation , John! Thank you!

[@Radagast97]

BTW, red devil lye is NaOH, a very good source of Na+ (group I metal ion), so would fall into the category of deflocculants I mentioned. Quicklime converts to Ca(OH)2 in water and is fairly alkaline. Given it's (Ca++) a group II metal ion source and alkaline, it would be interesting to see if it is a better flocculant or deflocculant. :)

[@johnbrittpottery]

Don't wash off your bisque. That is adding water to what I assume is a thin pot.You have just over saturated the "sponge". That is what bisque is like a sponge , so when you get it too wet it can't absorb any more. This also causes crawling of shinos.

[@happEdragon]

I was given a glaze and was told has gum in it, to keep it from settling. Although it looks very thick, when it dries on bisque, it becomes apparent that it really gives a very thin coat. Will the darvan 811 help counteract gum?

[@johnbrittpottery]

I don't think so. You might try Epsom salts...drop or two.

[@aseempandey9676]

Hi John, Thanks for sharing. Does your deflocculated clay settles with time? I observed settling over a period of 24 hours when I used sodium silicate for deflocculation.

[@johnbrittpottery]

This was about glazes. But in general everything changes over time as electrons are moving back and forth at all times. As far as slips, yes they can settle and get hard over time. That is why you need to maintain them. (casting slip) As for thickened slips they really don't because so much clay. (See thickened slips video)

[@TomMacGarrett]

so what is up when i dip a cup in a shino and it doesn't dry? most of the time the post dry fast, by if their is ANY moisture on the bisque cup from cleaning off the dust, the shino won't stick. and do any of these additives change specific gravity? thanks

[@ClayThrower]

So well done and informative!

[@MamereClaire]

Much thanks, Claire

[@AlvaSudden]

What does flocc/deflocc do to specific gravity?

[@debbiewilson958]

John for the glaze that flakes and cracks....... If I have already added water, which I should not have, what would be the process to get it where it should be?

[@Neldidellavittoria]

Add a bit more of the dry components.

[@matthewlittle3107]

Having a glaze issue. My glaze dries very fast, becomes powdery but it is also cracking on the inside corner of a cup and around the handle connection point. If I do a faster application the glaze is too thin and ends up having a very rough / dry outcome (post firing). It needs to be a thicker application, but the thicker the application the more cracking and thus crawling occurs. I am applying in 2 phases. I pour the inside, let it dry over night and then dip the outside. This is a magnesium based matte glaze based off of Tony Hansen's G2934Y. Thoughts?

[@____Ann____]

Hi John. I have some crawling with a glaze that needs to be applied thickly. If it is thinner it looks boring. How do I fix the crawling? Some cmc so that it can dry more slowly?

[@johnbrittpottery]

Have to know recipe...go on the group..."Exploring Midrange Glazes Together with John Britt's Book...lots of help there.

[@____Ann____]

​ It is Strontium Gloss Recipe number 39066 on Glazy Custer Feldspar 40.00 Strontium Carbonate 21.00 Silica 15.00 EP Kaolin 12.00 Ferro Frit 3134 12.00 Total base recipe 100.00 Rutile 8.00 Manganese 3.00 Bentonite 2.00

[@____Ann____]

​@@johnbrittpottery Thanks! I know about that group but I don't have Facebook.

[@johnbrittpottery]

Not sure why that would crawl?

[@free2throw]

Great video! Thanks so much!!

[@merrilymud7304]

thanks john!

[@DirtKickerPottery]

Thanks Glenn

[@Radagast97]

Very unlikely. For fit, the amounts used for flocculation/deflocculation are so small, compared to glaze ingredients, as to be insignificant. Crazing is a fit issue, see above. Pinholes and other defects are usually related how you glazed, not ingredients. Crawling perhaps, but only because flocculated glazes can allow you to glaze too thick which, for high clay glazes, will cause slight glaze cracking on drying (like cracked clay in a dry lake bed) leading to crawling when fired.

[@michellewalsh8752]

Hi. I bought a complete ceramic studio second hand, including some ready mixed glazes. Some of the glazes have as you described in your video have settled and are incredibly difficult to mix up. Is there anything you could suggest to stop this happening?

[@johnbrittpottery]

Yes you add epson salts...see the video on flocculated and deflocculate glazes..should explain. Let me know if you need more. Also check out the Facebook Group page...Exploring Midrange Glazes Together with John Britt's Book...great group and helpful folks.

[@michellewalsh8752]

Thank you for your advice, Sir Glaze Oracle. On the flip side I have some glazes that are a thick as pudding. Should I add water to these first? I live in Spain and my ceramic supplier does not have Darvan (any of the numbers) I can however, buy Sodium Silicate called (Silicato de Sodio Neutro 1L) I’m hoping this would work. I will also check out the Facebook page. Your videos are a God send. My Spanish is not specific enough to ask technical questions.

[@johnbrittpottery]

Try it. It works great. You can get high concentrations at green stores. Green pesticide. (20% acetic acid) Also, muratic acid. I think some use calcium chloride too. Here is an article that is through: You will have to google clay times and pete pinnell and adjust glazes.

[@huckhickson6955]

Does it work with underglazes?

[@johnbrittpottery]

yes, anything with a clay particle.

[@WaltPark]

Thank you!

[@johnbrittpottery]

No Hablo Español, lo lamento.

[@chathurimasakorala8384]

John Britt hello could u plz tell me what i need to make glaze coz this is my first time . I really don't know what I need lemme know the recipe sir??

[@meredithinserra4670]

It hurts my head to watch sciency pottery videos. LOL I need a 2nd graders explanation of deflocculation and flocculation. Ouch, it hurts my head to use words like that too. LOL I think I may need to stick with the creative side of pottery and leave the science to my pottery friends who are into that.

[@kettysack5063]

se puede traducir al español??? please

[@johnbrittpottery]

No.