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#119594 Really, Really Basic Question

Posted by JBaymore on 01 January 2017 - 12:33 PM

maybe not, john, what is the title of the book?


I don't write these initials often........ OMG!


"Clay and Glazes for the Potter" by Daniel Rhodes.  Last version  updated by Robin Hopper.





#119386 Raku To 05

Posted by JBaymore on 29 December 2016 - 10:42 AM

  But it does need a good gap between the burner and intake, so some of the surrounding air can get in, and help the gas burn.


Weed burners are basically "junk" burners. They are not intended for what we do with them.  They work just fine for what they are intended to do though........ because things that matter to us don't matter to someone burning off unwanted weeds.


The absolutely BEST available venturi type burners can entrain only about 65-70% of the air they need to combust all the fuel.  It is a limitation of the designs.  It simply cannot get better than that.  And those burners are not the ones typically used by the vast majority of studio potters.  Companies like Pyronics and North American make those types.  They are expensive.  (I have four Pyronics ones on my gas kiln.  They are precisely engineered and cast units.  Beautiful.)


So to burn all the fuel coming out of that orifice .... you MUST supply secondary air.  To do that... the burner/kiln SYSTEM must work together to entrain and MIX that extra 30% into the already burning and partly aerated mixture before it leaves the chamber.


The engineering start point for designing kilns is AIR.... not fuel.  No air...... no heat energy.





#119133 Raku To 05

Posted by JBaymore on 25 December 2016 - 09:55 AM



600,000 BTUs is plenty to fire that to cone 05.


Venturi or forced air burners?  What gas pressure if venturi?  What brand of venturi burners?


This is going to sound strange.... but try turning the burners DOWN more than you have been "pushing" them to get the temp up.  This is often a mistake people make who are not used to fuel firing.  Sometimes you are just burning the fuel outside the kiln after the exit flue.... or not burning a lot of the available fuel at all....and it goes off with the flue gases.





#119132 Silica In Glaze And Body To Ensure Good Fit?

Posted by JBaymore on 25 December 2016 - 09:44 AM



COE and what we typically call "shrinkage rate" are two different aspects of the materials.  They are not totally related to each other.


"Shrinkage rate" as potters use it basically means the permanent size change that happens as certain things happen to the clay body.  Some shrinkage happens as physical water of formation leaves the wet clay form.  This is usually called "wet to dry" shrinkage.   It is permanent (as long as you don't re-wet the unfired clay ;) ).  Then there is firing shrinkage as chemical water is driven off the clay crystals and the body starts to vitrify to one extent or another.  This is typically called "firing shrinkage".  It is permanent too.


This shrinkage can affect how a raw slip coating stays on the body as it shrinks.  This shrinkage can affect how, in the early stages of a firing, a raw not-yet-really-melting glaze layer might stay on the surface of the form.


Coefficient Of Thermal Expansion, or as I prefer to describe it to students as the REVERSIBLE Coefficient of Thermal Expansion, is related to a different situation for potters.  reversible means that as thngs heat up they expand and as they cool down they contract.  Important concept.  COE is dealing with size changes that are NOT permanent.  They are temperature dependent.


It becomes important when you have a FIRED clay body, and a chilled, or set molten glass layer on top of that body.  The idea of "set" when it comes to glaze means that the glass is now at a temperature below the state at which it is still fluid and able to flow to any degree.  The idea of "frozen water" is often used for this idea but that is technically incorrect.... because water is a liquid but ICE is a solid... with a regular crystalline arrangement of the water molecules. 


Remember as a side point that glass is not a solid even though our human senses tend to perceive it as such.  It is an amorphous association of the molecules that make it up.  Although a dated and slightly inaccurate expression.... glass is often called a "super-cooled liquid".


Once "set"..... like most materials, glass expands upon heating and contracts again upon cooling.  SO does fired clay.  The COE deals with THIS shrinkage aspect.  As the clay body and glass cool from the firing, you want them to shrink from THIS aspect (not related to the overall total shrinkage described above) at the same rate and amount.


If the glaze shrinks in this aspect more than the clay body... it becomes in tension.  Glasses are [pretty weak in tension.  SO the glass fractures to relieve the tension.  This is crazing.


If the glaze shrinks LESS than the clay body, this puts the glaze in compression.  Glass is quite strong in compression.  SO the glaze layer is now larger than the clay body under it.  This can cause stress relief by having the glass flake off the edges of the clay body.... called shivering.  In big cases... this can cause the clay body to rupture if the glass is stronger than the clay wall cross section.  This is one form of dunting.


A really bad combination for work is a piece with a glaze in compression on the inside, a glaze in tension on the outside, and a thin wall or weak clay body.  Explodo-pots. :D


Hope this description helps.





#118986 Wheel Speed When Trimming

Posted by JBaymore on 22 December 2016 - 10:57 PM

My approach to trimming is to take off a lot of clay very quickly... with the wheel rotating slowly.  Very sharp tools... kept sharp.  Instead of many multiple revolutions to get the clay off....... fewer revolutions.  Decisive cuts.





#118958 Trip To Japan To Study Ceramics. Ever Done This$

Posted by JBaymore on 22 December 2016 - 02:52 PM



Welcome to the forums.


I have spent a lot of time working and showing in Japan.  Cultural aspects make it hard to just "cold call" places or people there and have opportunities like this that you are looking for.  There are some ways to get "in the door",...... but they are limited.


One aspect of one of the 'Japanese cultural roadblocks' to introductions is that if a person such as myself were to recommend someone to a person over there.... I am putting MY total reputation there "on the line".  If that person screws up ....... (and that is easy to do)..... it is exactly the same as if I was the one that screwed up.  So people already "connected" in Japan are often very reluctant to recommend or introduce people that they do not know very WELL. 


Yes... it makes it hard.


There is a Japanese word/phrase that is useful to know with that thought ......... muzukashi.  (Moo zoo kah she) Literal translation is "It is difficult".  It is the Japanese polite way of saying "no" without saying "no".  When you hear that phrase.... you know that a door just closed.  Do not push on that door.  NOT pushing.... may.... open another door later.


That being said about the difficulties, there is a group that offers paid for ceramics experiences in Japan... and in particular in the Seto/Tajimi area (home of Shinowares).  They are called "Explore Japanese Ceramics".  You can find them as a group or page on Facebook.  (Tell them I sent you.  I know one of their founders a bit.  He has been to me studio.)  They do month long (or longer) "residencies" of sorts.  Prices are reasonable.  it is a start.


Once you are there and have an initial "connection", however you can arrange that situation and start to develop relationships... then more doors may open for you.  Note that the Japanese want to know you as a PERSON........ before you as a potter....... or for any kind of business venture.  Liking you goes a LONG way.


The best piece of advice I can give you if you are serious about this is to go get books on Japanese culture and study them.  There are many to choose from that are tailored for business travelers.  As a foreigner and one that is new to Japan... you will have what is known as "Gaijin License".  It means that you can screw up a little and get away with things that a Japanese person can't.  The key point is to not to have the USE that License.  The less you step into poor cultural behaviors.... the faster doors might open for you.


The next piece of advice is to start studying Japanese language now.  Get some of the CD type things and start practicing.  Rosetta Stone is fantastic.  Pimslear also offers cheaper alternatives.  Even rudimentary language skill goes a LONG way into earning trust.  Most foreigners don't even try.  That you try.... says a lot in Japan.  In Japanese they do not say, "Good Luck" when someone is about to do something.  They say, Ganbatte". (Gahn  Bat Tay)   Ganbatte means, "Do your best".  Very different way of thinking.


And the last piece of advice here is what was given to me by a dear friend and colleague who apprenticed there, on the occasion of the first time that I traveled to Japan for ceramic related stuff years and years ago.  "If a car door opens, get in.  If food is put in front of you, eat it.  Follow this and you will have experiences that you could not have dreamed of having while you are there."


Hope your interest and plans work out.  Ganbatte.





#118878 Should You Think Production Process If You're Not A Production Potter?

Posted by JBaymore on 21 December 2016 - 04:28 PM


so as of now i am ignoring the process and just figuring out the kind of pots i want to make.


Hummmmmm........ working through and with process helps you find what those pieces are.  Learning to have flows of multiple pieces in process at the same time, allows you to work thru ideas that develop FROM the work AS you work.  Simply sitting and thinking about it leads basically nowhere.  Biggest mistake we see in undergrads.


Hands in clay.





#118838 Wheel Speed When Trimming

Posted by JBaymore on 21 December 2016 - 11:18 AM

Always very slowly.  Prefer to trim on a wooden type kick wheel.... pulling with the left foot...... but not often able to take that luxury.


My CXC wheel has the footpedal always adjusted so that the max speed when fully depressed is WAY slow.


Clay scrap almost never "scatters".  I use a small shaving brush to move it off the wheelhead most times.  No splash pan. Scraps go onto the floor around the wheel.  Cleaned up while still wet.


I also center and throw at slow speed.





#118752 Should You Think Production Process If You're Not A Production Potter?

Posted by JBaymore on 20 December 2016 - 10:09 AM

I think the key point in this discussion is WHY a person is trimming a form.


If the trimming is part of an intentful CHOICE... that is one thing.  If the trimming is being done because there IS no other choice....... then the trimming is a "band-aid" being put on the "severed artery" of a lack of throwing skills.  THAT is a whole different animal.


All of the faculty at my college, including myself, address the idea of trimming as an approach to refining and completing the form for aesthetic (and possibly also functional) reasons........ NOT for reducing the weight or decreasing the wall thickness.


There is a saying that, "When all you have is a hammer, the world looks like a nail".  When you can't move clay up into the air well on the potter's wheel, all you can see is trimming tools. 


To persist in using trimming to solve this issue is to simply avoid the REAL issue.  It is the easy way out.


Early on in a potter's development, such an approach puts the object before the process; product before skill.  As a student of clay.... which hopefully continues for a lifetime...... acquisition of 'high touch' would hopefully be an important goal.


As to "right " and "wrong" on this............ since no one is going to DIE based upon how one gets to the end piece of claywork.... there is no essential and universal measuring stick.  However, there are skillful and efficient ways to get things done....usually referred to as aspects of "craftsmanship" (sorry about the gender specific nature of that word).  If high levels of "craftsmanship" are used as a measuring stick........ then HAVING to trim to reduce the weight caused by an excessively thick cross section is "wrong".


A finished object stands on its own.  In that context, no one cares HOW it came to be ............ including industrial forming processes.  It just "is".  We see and interact with it and form a judgment about it.  We can assess function.  We can assess aesthetics of design. 


Where does process figure into this equation?   Does it at all?


This opens up a whole different area of serious enquiry.   Is a poorly executed piece of hand-crafted pottery somehow "better", or have more intrinsic value, than a well executed industrially produced piece of pottery?


Now that I've opened THAT can o' worms......... I'll run and hide in a corner somewhere ;) .





#118738 Clay College

Posted by JBaymore on 19 December 2016 - 11:15 PM

Thanks for clarifying, Nerd. ( I hate calling you that.   :) )  


And yes....... there is passion.  Lifelong educator.  I care. 





#118530 Wadding Recipes Need Help

Posted by JBaymore on 16 December 2016 - 09:38 AM

Never seen the wadding with shelves before, does anybody have a picture?



Example in an anagama here:  gallery_1543_1269_413562.jpg





#118469 Simple Wadding For Supporting Pots In Electric Kiln Glaze Firing

Posted by JBaymore on 15 December 2016 - 10:05 AM

Hi, I  am new here and not sure how to post my own questions in a new forum. There doesnt seem to be any link to start a new forum question.


I have question on wadding. My boss uses a wadding mixture of 50 parts EPK and 50 parts ball clay that is mixed together with water to create a dough which we then use to put between the kiln furniture and shelves to act like a glue so that as we are building up the each shelf it is sturdy.  Do most people do that or is it not necessary?


My other more important question is we have a bag of Kaolinitic Clay powder which I know is an ingredient in EPK, but I need to make more wadding and and we do not have any more EPK. Can I mix 50 parts Kaolinitic clay powder and 50 parts OM4 Ball Clay and maybe throw in  alittle Alumina to make wadding for the glue part of our shelf making? 


FYI this would be for an electric kiln......


Any advice would be much appreciated :)





Top right corner of the main forum section page is a black button that says "Start New Topic"... Click that to cerate a new thread.


Using some wadding mix on shelf posts in any kiln is certainly a good way to make a stable load and get things really level.  In smaller kilns, unless the shelves and/or posts are pitted and/or warped.... it is probably a bit of "overkill".   For a soda, salt, or wood kiln........ it is pretty much a necessity to keep the posts from sticking to the shelf bottoms. 


In a larger electric or gas kiln (say maybe 40+ cubic feet) not a BAD idea to help make the load more stable.  In a 7 cubic foot hex electric.... with maybe a stack of 5-6 shelves tall at most........ probably not necessary at all.  But will not HURT anything.


"Kaolinitic Clay" as a term (unusual) basically says it is something that is more or less a kaolin.  Mix that 50% with 50% alumina hydrate... and you have "kiln wadding".  Any kaolin with 50% alumina hydrate will work as wadding pretty darn well.  In fact,...... for gas and electric high fire...... 50% kaolin and 50% silica works OK.  Or 33.3% any kaolin, 33.3% alumina hydrate, 33.3% silica is a pretty standard kiln shelf wash mix that makes a good (non woodfire/salt fire) wadding also. 





#118405 Just Dreaming ...

Posted by JBaymore on 14 December 2016 - 08:43 AM

Win the lottery, and wood fire until the money runs out.  :P


How do you make a small fortune as a wood fire potter?




........................................wait for it..............................




Start with a large fortune.  ;)   (bada-bing!)

#118388 Just Dreaming ...

Posted by JBaymore on 13 December 2016 - 05:12 PM

.........the land is there to build an anagama .................


There is a woodfirer's standard joke................


"What is the best woodkiln to fire?"






....................................." The one that someone ELSE paid to build and owns."






PS:  Anagama are "be careful what you wish for" kilns.

#118255 Gallery/co-Op Protocol

Posted by JBaymore on 11 December 2016 - 11:32 AM

If a gallery that handles you refers a client to you and they suddenly show up at your studio and buy........ the norm is "yes".


Click-throughs....... not so sure if it has reached the "norm" status yet.