clay shrinkage

[jrgpots]

I am using Laguna B-3 Brown clay with a 10% shrinkage to build Native American flutes. I extrude 1.1" and .825" diameter tubes as the starting point for the flute bodies. These should shrink to 1" and 3/4" after firing. The length of the tube determine the fundimental tone and the diameter and placement of 6 holes sets the scale notes.

 

So here is the crux of my post..

1. How much shrinkage occurs from wet to leatherhard stage? From leather to bone dry?

2. I have been tuning the flute during at the leatherhard stage. Should I tune sharp (sharp equals larger hole) by 10%- leatherhard shrinkage as an estimate of pitch?

3. How hard will it be enlarge the holes after cone 6 firing?o

 

Has anyone had experience flute making that could give their two cents worth? I know, "test, test, test."

[Pres]

I am using Laguna B-3 Brown clay with a 10% shrinkage to build Native American flutes. I extrude 1.1" and .825" diameter tubes as the starting point for the flute bodies. These should shrink to 1" and 3/4" after firing. The length of the tube determine the fundimental tone and the diameter and placement of 6 holes sets the scale notes.

 

So here is the crux of my post..

1. How much shrinkage occurs from wet to leatherhard stage? From leather to bone dry?

2. I have been tuning the flute during at the leatherhard stage. Should I tune sharp (sharp equals larger hole) by 10%- leatherhard shrinkage as an estimate of pitch?

3. How hard will it be enlarge the holes after cone 6 firing?o

 

Has anyone had experience flute making that could give their two cents worth? I know, "test, test, test."

 

 

No experience, but if I remember correctly much of what you are asking is in the book Mud to Music.

 

Link to a web site here:

 

http://ninestones.com/frommudtomusic/

 

Maybe you can find a copy at your local library or order one. It is an excellent resource for anyone working with ceramic instruments.

[Mark C.]

The only way I know is to make a shrinkage bar -you can search here on how to then as its in 10 millimeters you measure it in those various states and its a straight percentage. I have this info wet to bisque and bisque to cone 10 on a few bodies but not the info you need.

Mark

[jrgpots]

I am using Laguna B-3 Brown clay with a 10% shrinkage to build Native American flutes. I extrude 1.1" and .825" diameter tubes as the starting point for the flute bodies. These should shrink to 1" and 3/4" after firing. The length of the tube determine the fundimental tone and the diameter and placement of 6 holes sets the scale notes.

 

So here is the crux of my post..

1. How much shrinkage occurs from wet to leatherhard stage? From leather to bone dry?

2. I have been tuning the flute during at the leatherhard stage. Should I tune sharp (sharp equals larger hole) by 10%- leatherhard shrinkage as an estimate of pitch?

3. How hard will it be enlarge the holes after cone 6 firing?o

 

Has anyone had experience flute making that could give their two cents worth? I know, "test, test, test."

 

 

No experience, but if I remember correctly much of what you are asking is in the book Mud to Music.

 

Link to a web site here:

 

http://ninestones.com/frommudtomusic/

 

Maybe you can find a copy at your local library or order one. It is an excellent resource for anyone working with ceramic instruments.

 

Thanks for the direction. I have to get the book!

[jrgpots]

The only way I know is to make a shrinkage bar -you can search here on how to then as its in 10 millimeters you measure it in those various states and its a straight percentage. I have this info wet to bisque and bisque to cone 10 on a few bodies but not the info you need.

Mark

 

 

I'm afraid I will need to make shrinkage bars also. But, the flute has a bright tone to it even in leatherhard state. If it works out, I will post pics and an audio file.

[Marcia Selsor]

I make shrinkage test bars any time I use a new clay. It is amazing the variations. I find I usually have close to 5% in the bisque stage for most clays and porcelains that I use.

Then it will vary for the final firings. Some porcelain is 12-13%

Disheartening when the firing large pot comes out so small. Good luck with the flutes. I have collected a few. I admire people who can make them. It isn't easy iMO.

 

Marcia

[neilestrick]

I think no matter what you're going to have to do some tuning once it's fired. I guess the big question is whether you just need it to be in tune with itself from note to note, or if you need it to be in tune with A440. If just with itself, then if it's in tune when leather hard it should be in tune when fired. If you need it tuned to A440 you'll definitely have to do some work after firing. Just remember that you won't be able to add clay to bring it into tune. You'll only be able to remove clay by drilling or grinding. But cone 6 clay is not that easy to drill or grind. Wet drilling or grinding is best, so the piece doesn't overheat and crack.

[Biglou13]

Less destructive tuning maybe using epoxy to fill space depending on flute design, and if it doesn't change harmonics, but you're out of luck if you need to add legnth to tune.

 

But since its a ceramic flute you might not be expecting such exacting standards.

[jrgpots]

I think no matter what you're going to have to do some tuning once it's fired. I guess the big question is whether you just need it to be in tune with itself from note to note, or if you need it to be in tune with A440. If just with itself, then if it's in tune when leather hard it should be in tune when fired. If you need it tuned to A440 you'll definitely have to do some work after firing. Just remember that you won't be able to add clay to bring it into tune. You'll only be able to remove clay by drilling or grinding. But cone 6 clay is not that easy to drill or grind. Wet drilling or grinding is best, so the piece doesn't overheat and crack.

 

 

 

I made my first clay flute from poymer clay... easy as a lark. It is a great point about not adding to the flute length to get a lower tone. I t will take tial and error. I plan on making many of these things so I hope I will be able to better predict after a few ( hopefully not more that 20...lol) the size, pitch , etc. I will be making B flat , as welll as C and others. Initially it will be tuned to itself. In the future it may be tuned to actual scale.

 

Just watch, I will do all this and be the only one who wants a ceramic flute. Then again I may be in the process of making a boat load of "Christmas and birthday" presents for lots of DISTANT relatives. I can imagine it now... "ANYBODY want an extra flute?"

 

My first flute is bone dry now. Soon to go to the kiln..

 

Jed

[jrgpots]

Less destructive tuning maybe using epoxy to fill space depending on flute design, and if it doesn't change harmonics, but you're out of luck if you need to add legnth to tune.

 

But since its a ceramic flute you might not be expecting such exacting standards.

 

 

 

I expect a lot, but will settle for a whole lot less. You are right I can always fill some part of the holes with epoxy. I can even extend the flute with epoxy. I Have had to do that with wood. I might as well expect to do it with clay also...

 

I 'm excited to see the result. I used dark brown clay and will be glazing with an oatmeal base and tomato red over the oatmeal at the end of the flute.

 

Thanks for the advice,

 

Jed

[megzwakefield]

my kid has those kind of clay that he bought from the school. i guess that those are just the simply kind of clay, isn't it. but i wonder i can make use of it as a possible material for this kind of work? or their are really specific kind of clay just for this purpose also?

[jrgpots]

my kid has those kind of clay that he bought from the school. i guess that those are just the simply kind of clay, isn't it. but i wonder i can make use of it as a possible material for this kind of work? or their are really specific kind of clay just for this purpose also?

 

 

 

The polymer clay is easy to work with. It hardens in the oven at about 225 degrees. it takes about 20 to 30 minutes to harden in the oven. Lots of people use it to make jewelry beads and sculpting projects. It hardens to hard plastic. It is not very durable and easily breaks, so its uses are limited. But it's a good place to start to see if you like working with clay. Most people here will be talking about ceramic clays. There are 5 groups of ceramic clays that are cured in a kiln much hotter than the oven.

 

1. low fire... used in pit firing.

 

2. Terra cotta... This is the orange clay used in making flower pots and roof type.

 

3. Earthenware... It is harder than the first two clays and can be glazed. it will leak if not glazed.

 

4. Stoneware... It is harder and great for making dishes and cooking ware. it is water tight.

 

5. Porcelain... This clay can be made into fine china. It is strong and can be very thin and almost translucent.

 

Try using the polymer clay that your son got from school. You may find you enjoy it and get hooked like most of the people here.

 

Jed