Anyone heard of Calispar?

Mike the only thing I could find on the web was an Indian site that wouldn't load. There are other resources to check for material information, but they won't load either...damn viruses! I'll put it on top of my list, and do some more research when I can.

could it be Cal-Spar?

Are you sure it's Cal potspar? There was a Cal N spar, which was a soda spar. The RO column was 1 NaO

Regards, June

Here's the formula for Calspar Potash feldspar

Calspar K Mol. Weight: 623.25

Category Feldspar Fill Oxides KNO

Molecular Analysis:

K20 0.395 Al2O3 1.040 SiO2 7.306

Na2O 0.373 Fe2O3 0.009 LOI 0.208

Regards, June

MgO 0.009

Thanks for the info. These posts have been a great help to me. I think Calspar Potash Feldspar must be what the material is. Now if only we potters could learn to label/spell materials correctly. There would have been no question what the stuff was.

- Mike

You can do a button test of the material next to another potspar. If it's potspar the melt should be pretty close. If it's the cal soda spar, it will melt quite a bit more. Also, when you are looking for information on raw materials the Matrix glaze software site had a database of raw materials and the Tony Hansen Insight software site does as well. Any search engine will find those for you.

Regards, June

Make a slab of clay about 5X8" and about 3/8" thick. Bisque it. Then fill a thimble (I use a porcelain thimble type tiny cup available at medical/laboratory equipment tores). Press the spar in there enough to compress it so it will stay intact when you invert the thimble or cup onto the bisqued tile. Use some stain or ceramic marking pencila to put the name of the spar in front of it; but make sure you leave at leave about an inch of space to allow for movement of the material during the firing.

Then move down the slab and put another Potspar or soda spar. You can fit a bunch of them on one tile. Then fire to cone 10 and you will see the level of melt, the color and what if any crazing that particularly spar exhibits.

Regards, June

Thank you! (would it serve any good to make thimble sized indents into the slab before bisque firing or do you want to see the spread?)... Donna

You probably wouldn't get the indents deep enough to do a proper job; and then you'd have to make sure your indents were all the same size. The thimble types give you are better indication of just how much each one melted.

Regards, June