Sunday, June 5, 2011

about those glaze tests-

 More details on those glaze tests from the last post.-  I felt I should do a little checking on a couple of glaze ingredients, epsom salts and borax, I used recently on test tiles.  Mainly, I wondered if one or the other might damage the kiln elements. I found nothing that indicates this could happen.  Someone let me know if it does?

About Borax. O.K. I remember now. Back (way back) when I had just graduated from college I was looking for a way to work in clay. The problem being that I had no money to buy equipment and no space for it. I did a little research (without the internet- Wow!) and found info on handbuilding pots and doing pit and sawdust firings. Glazes were minimal, and included terra sigillata and a kind of slip with borax added. The borax acts as a low-fire flux. I tried these methods and got some interesting results. A lot of nice flashing from the pit firings, especially. I found it difficult to get the clay hot enough to vitrify using these methods, though.
Here's an interesting article showing a spatter-on method with borax. I wonder if I could get salt/soda fired results in my electric kiln doing this.
Here's another source for borax:
This next one answers another question I had- Can I use the stuff off the shelf in the laundry aisle at the grocery store? Apparently, yes. Which is what I took a chance on when I made up the glaze test. I wanted to make sure before I made up a whole bucket load of the stuff, though. Here's a thread about that:

The info on epsom salts was new to me.  Hey, why I didn't already know this? Epsom salts is used to keep the glaze in suspension.  Many of my glazes call for bentonite to do this.  This is the first time I've come across using epsom salts.
Check out this link-
And this explains why my Grace's yellow glaze is rock hard and takes 45 minutes of hacking and stirring to make usable.  Why didn't I know this?!!!

This is where I got the recipe for the Chun glaze.  It was posted on Peter's Pottery.  He suggests adding 10-20% borax to lower the firing temp to cone 6.  I used 10%.  I'm not familiar with what a chun glaze is supposed to look like by itself.  I would say this one is satin, mostly smooth with just a slight orange peel texture.
He layered the chun over a temmoku glaze.  There was one I've been wanting to try.  This Temmoku Gold is from Frogpond Pottery and it really does have flecks of gold.

A little rehash on the pictures-

 Back row, second from right is the Temmoku Gold.
Front row, middle is Chun.  Second from right in that row is Chun over Temmoku.  Far right is Chun over a brown engobe.

The epsom salts are in the clear glaze- back row, the first 3 test tiles. First is clear, no colorant. The next 2 with colorants, obviously. All the rest are Grace's yellow. I upped the rutile a little and played around with brushing a couple of clears w/Fe over the glaze here and there, which basically had almost 0 effect.  These are cone 6 glazes.

This looks very similar to the Chun over Temmoku combination but is actually Grace's blue over Albany Plum. Used a wick holder as I was out of test tiles. 

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