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Member Since 31 Mar 2010
Offline Last Active Aug 15 2016 07:52 PM

#111427 Making A Glaze More Runny

Posted by Min on 15 August 2016 - 07:50 PM

This topic came up a few months ago and Paul Lewing seemed to have the best answer,

"Posted 25 March 2016 - 08:41 AM

The solutions to your problem that have been proposed have all been process or physical fixes, but the root of your problem is chemical.  If you want glazes to bleed a long way into each other, they need to be very dissimilar.  Conversely, glazes that are similar will bleed into each other less.  And the key area of difference is Si:Al ratio.  If the two have ratios have difference from each other that is greater than 6 they will definitely bleed a lot.  For instance if one has a Si:/Al ratio of 5 and the other has a ratio of 12, expect a lot of bleeding.  This of course makes sense.  One is deficient in silica, the other is deficient in alumina, so the go looking for what they need in the other.

So... bottom line, if you want no bleeding at all, your best bet is color variations on the same glaze.  Doesn't matter what glaze it is.  The the only variable will be how much of a flux or refractory the colorant is in each different color variation."


An easy way to make your G1216M glaze more runny would be to just decrease the alumina, (epk in this recipe), test by running a line blend. It will increase the likelihood of crazing though.

#111340 Supplies To Buy When Buying A First Wheel?

Posted by Min on 13 August 2016 - 02:31 PM

I think even your 24 gauge aluminum is going to be thick for a flexible metal rib. I put a micrometer on one of my stainless ones and it’s 0 point 1 mm.  Your aluminum might be good for rigid ribs though.


I personally don’t like the Xiem soft rib that I have, it’s way too thick compared to the Sherrill (MudTools) ones, doesn’t bend as nicely so kinda defeats the purpose of buying a soft one. 


For foam, you can save yourself some money and just use some scraps of upholstery foam when throwing, the high density stuff lasts ages. (Robin Hopper workshop tip) Old chair cushion or scraps from a foam shop. A cleaning cloth for eye glasses works really well for smoothing rims and never seem to wear out.


Pic of the thickness difference between soft Xiem (orange) and Sherrill (red) soft ribs. Plus a flexible stainless one.


 (you can kind of see the difference in the rib thicknesses)

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#111206 In Search Of A Great Transparent Glaze

Posted by Min on 10 August 2016 - 04:03 PM

My favourite ^6 clear for over underglazes on porcelain is this one https://digitalfire...._cone_6_45.html. The 3249 frit is ridiculously expensive but I've done a version of this glaze subbing other stuff for it if you want it. Never boron cloudy, super forgiving glaze. (spectrum underglazes)


(porcelain kids bowls)

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#111052 Qotw: Clay Poem Anybody?

Posted by Min on 06 August 2016 - 06:46 PM

perhaps it’s the heat

my brain like sausage meat 

that makes me quite odd

alas to the kiln shed i plod


load in the pots

my sciatic nerve now in knots

program the firing

kiln gremlins conspiring?


then back to the wheel

that holds most appeal

till i make a mess of it

that i can do lickety split


must remember to mop the floor,

a chore i adore

no mess in my space!

said with a poker face


i'm starting to think,

said with a nod and a wink 

i have a screw loose

hmm, glaze chemical abuse?

#110795 Qotw: Are Our Expectations Too High?

Posted by Min on 31 July 2016 - 09:59 AM

I wish this young lady and long and successful career in the arts.


(long add before the video)


#110669 Mixed My A First Batch Of Glaze

Posted by Min on 27 July 2016 - 06:14 PM

If you are going to be brushing glazes on I would mix those glazes with a brushing medium rather than water. Glaze dries slower and flows from brush to pot easier. But once you get the hang of dipping or pouring glazes I doubt you will want to go back to brushing since it takes so much longer.


My guess would be the glaze is too thin on the high points of the scallops, maybe application, maybe overfired?


If I may make another suggestion, if you are not already doing it, for your dipping test I would measure the specific gravity of the glaze and make note of that plus the length of time you dip the pot for. Makes it easier to replicate successful glazing on future pots until you get to know the glaze well.


What is the pink tint from? 


Good stuff for your first go at this!  :) 

#110662 Qotw: Are Our Expectations Too High?

Posted by Min on 27 July 2016 - 04:46 PM

I’m going to go with what Joel wrote and bounce off that.


The Stanford Marshmallow / Cookie Experiment demonstrated that those people who could delay gratification tended to be more successful in many areas of life than those seeking immediate gratification. (done pre internet in the late 60’s and early 70’s)


Extrapolating from that, perhaps the people who keep plugging away at ceramics are those that are able to practice delayed gratification.

#110548 Replace Frit 3134 With Gerstly Borate

Posted by Min on 25 July 2016 - 07:34 PM

If you post the recipe it would be a lot easier for someone to possibly work out a glaze using g.b. in place of the frit. 


One thing I really like about these forums is the knowledge gained by all of us through information sharing and suggestions. Someone coming back to this post at a later date might gain insight from your question and possible answers, if they can see the original and adapted recipes. (that being said, if your glaze is a “trade secret” I can understand why you might not want to post it.  ;) )

#109610 Qotw: Are We Potters Crazy?

Posted by Min on 29 June 2016 - 01:29 PM


#109370 Crazing - Commercial Glaze

Posted by Min on 25 June 2016 - 01:08 PM

I agree about adding silica and alumina to fix crazing, if the base can support the amount needed to do so. Otherwise you need to change the fluxes, obviously not possible with a commercial glaze.


I think there is another way of looking at coe figures and their relationship to crazing. That being to look at glaze “families” or “systems”.


This is from digital fire:

Results are determined by the set of expansion numbers (different values are available from different sources) and the method of additive calculation method chosen (based on formula or mole%). Thermal expansion values predicted by calculation are relative (not absolute) and apply within 'systems'. Thus, if a glaze calculates to a higher expansion than another, and is in the same system, then it is more likely to craze. For example, if you have a dolomite, whiting, feldspar, kaolin, silica glaze and you try a bunch of variations, the calculated expansions will give you an indication of which variations have higher and lower expansions. But if you introduce lithium carbonate, or boron frit, or zinc, for example, now you have a different system. Also, some oxides, like Li2O or B2O3 do not impose their expansions in a linear fashion, thus they do not calculate as well.



I use a clear with a coe of 5.76 (using Insight). It is bombproof and does not craze on my clay, have used it for many years. Using the same clay I recently ran some tests for a friend with a glaze that has a coe of 7.20. I tested it on the same porcelain clay that I use the low expansion glaze on. To my amazement it does not craze either. I ran exhaustive crazing tests on it and all samples are craze free.


Neil E. got me thinking about this when he posted his clear glaze for porcelain a few months ago. At the time it didn't seem logical to me why it didn’t craze since the coe came in fairly high. Now it makes sense. 

#109291 Bubbles/craters All Over

Posted by Min on 23 June 2016 - 09:13 PM

I think glaze blisters are one of the harder things to narrow down the cause of since there are so many possibilities for what the culprit is. If you feel like doing some reading there is a link to a Ceramics Industry 4 page article on blisters below, hopefully something seems a logical avenue to explore to fix the problem.

page 1 here http://www.ceramicin...blisters-part-1


links on lower left corner for parts 2,3 & 4.


A separate topic would be the problems of using a clay and glaze with such wide firing ranges as these have. 

#109201 Zircopax Kiln Shelf

Posted by Min on 22 June 2016 - 03:01 PM

This looks interesting, if you could get the zircopax for a decent price. Be nice to have an alternative to Advancers or Corelites for lighter shelves, plus to be able to make ones own.


(ps, HighBridge, there is a little bit on bubbles in glazes 1/2 way down the same page)


Bottom of this page http://digitalfire.com/index.php


#108796 Qotw: What Is Your Biggest Safety Fault?

Posted by Min on 15 June 2016 - 03:32 PM

Thinking I'm bigger and stronger than I really am and wrenching my back muscles when lifting. That and procrastinating over doing core exercises to strengthen it.

#108496 Feet For Slab Work

Posted by Min on 09 June 2016 - 10:30 AM

Stumbled across a neat idea for making feet from slabs. 

Foot cutter from a corn cob holder: http://www.grpottery...2503/footmaker/


I think I would probably stick with extruded ones but maybe an option for some.

(check the prices on the forms if you are looking for one)

#108485 Qotw: What Would Be The Title Of A Clay Book Of Yours?

Posted by Min on 09 June 2016 - 02:03 AM

Real Life Ceramics

A Collection of Experience, Knowledge, Wisdom and Humour while Working as a Ceramic Artist.


Wouldn't be my book though, I'm thinking.....


Mark C on tales of 40 years in the trenches and the sense of humour needed to survive it. 


John B would lead up the chapters on chemistry (that would be a book in itself). 


Mea on the practical aspects of business and beauty through simplicity.


Marcia, Alabama and Pres on being a life long practitioner and still loving the craft. 


Neil E. on how to fix damn near anything.


Joseph on dogged determination and perseverance. Joel with a chapter on the importance of asking questions and questioning everything.


Mathew on just getting out there and doing it.


Johnny K, what else, photography with explanations. tch, with thoughts on going down paths not intended.


Giselle and Callie on the trials and tribulations of working from home with young children.


Evelyne to be the editor with help from O.Lady (if she could just learn where the shift key is)


And Nerd to come along and throw a screw in the works just when some of us are starting to think they understand a tiny bit of all this.  ;)