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Member Since 15 Mar 2013
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#124899 Making Glazes

Posted by jrgpots on 05 April 2017 - 07:57 PM

You could find out what a cup of each of your ingredients weighs, then multiply the # of cups by each individual weight.  You would have what is in each glaze by weight.  At that point you could add ingredients as needed to get it to the desired recipe.


It's work, but the 4 buckets of glaze material could be salvaged.



#124697 Engobe And Glaze

Posted by jrgpots on 02 April 2017 - 04:08 PM

I really like the look you have achieved. I have never been a fan of solid white backgrounds. Your background reminds me on a skiff of snow. A thicker application would fully opacify the background. What you have now is more interesting in my opinion.


#122899 New Crop Of Flutes. I Need Critiques

Posted by jrgpots on 25 February 2017 - 11:21 AM

Dude, sweet. I hope you can load a sound file. I would love to hear them. I love the colors. Does it matter if you tune them? Who knows what they should sound like. They sound like they sound. That's cool enough.

Aah ..... but not if they're to be played along with other instruments! And/or for conventionally notated music.
Number 5 is my favourite - as Lee says - personal taste.

Most native American flutes will never be played with concert instruments. But most are played in flute circles. So the flutes have sound good together.


#122817 New Crop Of Flutes. I Need Critiques

Posted by jrgpots on 23 February 2017 - 04:17 PM

I just finished 10 new flutes. I am experimenting with glazes and clay bodies on the different flutes.  I just tuned these 6.  I would like your thoughts.  The tape ( red and black) is used to tune them. Eventually each with have an ornamental figure to replace the tape.


Can I upload a audio file of the flutes to the forum?




Attached Files

#122206 Why Didn't Someone Tell Me About Paperclay!?!

Posted by jrgpots on 13 February 2017 - 01:28 AM

I make native American ceramic flutes. I have 10 in various stages of construction right now. I wonder how the use of paper clay might affect (or is it effect?) The tonal qualities.

The beautiful tonal qualities of the violin depend on how the instrument resonates. A soft wood such as spruce is used on the back of the violin to improve resonance.

When I switched from wood flutes to ceramic flutes, I noticed that the ceramic flutes had a "brighter" tone. I wonder if the porous nature of paper clay would make the paper clay flute sound more like their wood counterparts?

Then again, I probably am the only one interested in such a question...


#112298 Very Cool Ulexite Oil Spot Glaze, Cone 6

Posted by jrgpots on 30 August 2016 - 11:27 PM

I found a very nice oil spot glaze posted on Facebook by Clara Giorello.   She took a cone 10 oilspot glaze, "Daly's oilspot" and changed it to a cone 6 glaze by adding Ulexite.   I had not even heard of Ulexite before, so a google search taught me that Ulexite is a sodium borate mineral.  It is also known as Sodium Calcium pentaborate octahydrate.  It sounds like very cool stuff.  It forms complex crystals that refract the light.  It is known as "TV Stone."   It is similar to Colmenite without the Silica and alumina.  Gersley borate has a small amount of it.  Clara Giorello ground the mineral herself.


Her recipe is: cone 6


K feldspar           40

quartz                 30

Talc                     10

Kaolin                 10

Ca Carb              10



add:   RIO           10

          Ulexite       10.



I tried to find a supplier for Ulexite.  I found an import company that was willing to sell me a metric ton of the stuff.  Has anyone ever used this and by chance found a distributor?



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#111391 Coma Clay

Posted by jrgpots on 14 August 2016 - 09:21 PM



Marcia: I gave it the name "coma", because the clay has no memory. 0.18% MGO, 0.31 FE.. ultra white at bisque/maturity.







Coma clay...........If  you fired it beyond the point of vitrification ,, you call it "Coma-toast".    .......just a thought. :D


All kidding aside, it looks great.

#111095 My Kiln Build

Posted by jrgpots on 08 August 2016 - 01:05 AM

Olsen calls the straight brick sandwiched between the skew brick and the arch, a "throw brick."  I had never noticed this before and was curious about it.


I built my arch support wider than you suggest.  It is 34" WIDE.  That is a 1 1/2" overlap on each edge.  Olsen gives a minimal arch rise 1 1/2"/ft and a maximum of 3" ft.  So I will rebuild the support to the right width and a 6 " rise.  That keeps the kiln in the cube shape.   My final kiln space will be 15+ cu ft. (not bad for a beginner).


I will widen the flue. I like the idea of adding a split if needed.


I was rushing to get as much built this past week because this Wednesday I will have disc replacement surgery on my neck.  I will not be able to lift anything greater than 2 lbs for 2 weeks. (I hope it is only 2 weeks).  As you know I live in the desert.  And we almost never get rain.  Yet as soon as I started the kiln it has rained here for 5 days straight.  My friend in the neighborhood told me I had to stop building the kiln before we all floated away.  We have had about 7 " of rain in 1 week.  We normally only get 9"-11" in a year.. The rain gods need to talk to the kiln gods more often. Their cooperation would be very much appreciated.


Mark, Bruce, Neil, Marcia.... Thanks for your help... I would have hesitated more before starting project without your back up.



#110741 My Kiln Build

Posted by jrgpots on 29 July 2016 - 08:47 PM

I am finally getting around to build my kiln.  It will be about 16 cu ft in capacity.   the outer measurements are 43' x 43."

Here are the first pics from the project.   More will follow.



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#110306 Your Refractory Is Toast

Posted by jrgpots on 19 July 2016 - 11:45 AM

If you soaked the loaf of bread in Sodium silicate and compressed the loaf with a 10- 20 ton press prior to placing it in the chamber, then fired it in an Argon environment, you would have silicon carbide.....a kiln shelf.


There is a great article Feb 2005 Science daily about making petrified wood using similar technique.   They placed wood in acid to breakdown the cellulose a bit, then soaked it in hot sodium silicate.  It went into an Argon oven and came out petrified.    So you could make a kiln out of wood if you wanted to..






#110230 How Much Granular Manganese Dioxide?

Posted by jrgpots on 17 July 2016 - 08:03 PM

I have used basalt granules instead of manganese to speckle my white clay body. i have used 20-40 mesh grains in a concentration between 2 - 4 %. It is not toxic and gives a nice cookie and cream appearance.... just a thought.  It also doesn't play too badly with any glazing.

#109604 Birdhouse In Chinese Red

Posted by jrgpots on 29 June 2016 - 10:06 AM

wrens like to fill up any cavities that might entice other birds to move in too close to the wrens.  and their babies return to the house for some time after they begin to fly.  yesterday, the mother scolded my dog for walking into her yard.  



Years ago we had a pair of wrens claim our enclosed atrium.  We left a small upper window open.  The window had no screen.  So once the nest was made, we did not close the window until all the wrens left the nest an didn't return at night... The music was great. They sang as we ate breakfast.  Watering the atrium plants was not so easy.


  The nest was in an old discarded pot.







#107946 Mixing Clay Bodies To Get Desired % Shrinkage

Posted by jrgpots on 01 June 2016 - 07:10 PM

As Min mentioned, both clay bodies are cone 5, so it will not be as bad as mixing earthenware and stoneware.  it will be more like adjusting shrinkage by adding grog.  The changes in shrinkage comes from the added grog content.  I hope.


Yes, I use a shrinkage ruler.  I  measure the % shrinkage from wet (fresh out of the extruder) to bisqued as well as from bisqued to  vitrified. Knowing the amount shrinkage at each step makes it easier to predict hole placement.


I want to clay with a little tooth in it for strength, but more importantly I want to get as close to 10% shrinkage as possible.  I make Native American flutes.  The diameter and length determine the fundamental pitch, key and hole placement. Just a mm difference can drastically alter the sound.  I  tune the flutes after the bisque firing and tune then flat by  the amount shrinkage will occur in the final firing. Tuning at this point is much harder


My issue is that since I just got a new extruder, I need to make new tube dies.  My old dies don't work in the new extruder.  So, since I have to make new dies, why not try to simplify my calculations. I want the final tube diameters to be 1" and 3/4" after firing. Everything would be easier. For example, if the shrinkage were 10%, the linear length would be .90 of original and the area would be .81 smaller (almost 0.8).  I can calculate these in my head. It makes it much easy for hole placement and tuning.  But first, I have to make new tube dies.  Is everything as clear as mud?


I have about 100 lbs to play with  so the "test, test, test"-ing will start tomorrow. 



#107877 Community Challenge #6

Posted by jrgpots on 01 June 2016 - 12:53 AM

Has anyone thought about a more abstract self portrait?



#106339 Metal And Arcing In An Electric Kiln

Posted by jrgpots on 05 May 2016 - 02:15 PM

If the nails were galvanized, the galvanized material will "burn off." It kind of looks like sparking.