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Firing Log

ancient kiln | 21st century logbook

March 1, 2009

Melting Floor Sand

Filed under: anagama, 11th,anagama, 6th,Firing,glaze,Pieces — odin @ 7:14 pm

I have received some surprise when I mention that my floor sand melts during firings.  It really does, but it will only become glassy where it is thin enough to spread out on something harder, like the bricks I pointed out in my previous post.  Where the sand is thick, only the top layer will melt.

Here is an example from the sixth firing, one of the most beautiful firings and the most disastrous due to multi-level shelf collapsing.

melted floor sand  Full size image.

This piece was just back of the firebox — a band of black koge can be seen in the front of the image.  The rest of the images from the sixth firing are posted on this site, but the location is pretty buried — I should add them to the photogallery.

Anyway, Furutani’s kiln design has no trouble melting sand.  In fact, it is beginning to dawn on me that I will have to work harder to keep firing temperatures down a bit, as I believe I’ve been overfiring to some degree.


  1. Hello Odin: I have a sand floor. Do you use silica sand? I have used some masons sand before and it contained some Feldspar and melted also. The silica sand seems to hold up fine for me, but it would be nice to know what sort of sand you use. I may be on the edge of disaster and not know it!!
    Thanks for the great site!!!

    Comment by Craig Edwards — March 2, 2009 @ 2:14 am

  2. The sand I buy comes from the Lane Mountain Company: White Silica Sand. They claim over 99% SiO2. From a sheet on the sand:
    Property Typical Value
    Silica (SiO2), % wt 99.56
    Aluminum Oxide (Al2O3), % wt. 0.24
    Iron Oxide ( Fe2O3), % wt 0.042
    Calcium Oxide (CaO), % wt. 0.0051
    Magnesium Oxide (MgO), % wt. 0.0079
    Titanium Dioxide (TiO2), % wt. 0.016
    Loss on Ignition at 1180 C, % wt. 0.13

    Comment by odin — March 2, 2009 @ 10:55 am

  3. aluminum properties…

    So, today is Monday and I was searching around for aluminum properties on google and you came number 3 in the UK, Just thought you would like to know….

    Trackback by aluminum properties — May 4, 2009 @ 1:28 pm

  4. great website odin! just looking at the photos from this firing it seems like you definitely got hot, really hot. are you still using only up to cone 11?

    Comment by zach sierke — August 12, 2009 @ 1:20 pm

  5. I’m fairly sure it is exceeding cone 11, but I don’t have any higher cones to see exactly where. It is possible however, that my temperatures are not that high, and I’m just seeing the effects of extended firings. The only evidence I have that the temperature is rather high, is the color from the firemouth at high temps: white, with severe purple blotches in visual field when looked at without welding goggles.

    Comment by odin — August 12, 2009 @ 2:25 pm

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