November Third Friday Commercial Cone 6 Glazes: Crawl Glazes

By Marsha Neal Studio

Welcome to the November 2010 Cone 6 Commercial Glaze Post.

This month I wanted to try out some Crawl Glazes I've have been fiddling with but haven't really ever gotten into testing fully.
I don't know why - I just haven't.

Marsha Neal Studio Detail of Cone 6 Crawl Glaze Tests.

The picture above is just a quick sampling of some crawl glazes from my 5 test tiles. I have also heard this type of glaze referred to as lichen glazes (any other names, please post in comment). The overall thing is that when you are applying them in nice thick coats, they crack upon drying. The part that does not crack should stick to the underlying material. Just like any other good clay to glaze bond.
The edges can be very sharp or rough, so keep that in mind - especially when glazing beads that may come into contact with bare skin or clothes.  

Underglazes, Application of Crawl Glazes, After "Glaze Firing" @ Cone 5.

The way I set up these tests were to take some 4" square textured tiles that were bisque fired to Cone 04,

Glaze in lines with varioust Amaco Velvet & Spectrum Underglazes (1-2 coats were all that was necessary).

After drying I applied lines of the 5 different crawl glazes perpendicular to the lines of underglazes.

I then fired them in my small kiln to Cone 5 (not cone 6 because in my smaller kiln, that would have been hotter than cone 6 - it's a heat vs temperature thing). 

While glazes are drying, cracks can be seen forming...

If you enlarge the above picture, you can see the cracks forming as these areas are drying. If you don't see cracks now, you probably won't see any after the firing. 

Five test tiles: Underglazes on Front, Listed on Back (flipped so they actually match photos), After  Cone 5 firing.

The Crawl Glazes in the above tile are from top to bottom:
(Click on the names below to go to the mfgr website).

Amaco, Arroya Soft White

Coyote, Blue Crawl #62

Coyote, Cactus Crawl #63

Coyote, Chocolate Crawl #64

Georgies, GLW15 Jujube White

Ok, so you can see that in the above picture, when you click on it and enlarge it, that the underglazes help change the color of some of the crawl glazes. I really like that - and the way the underglaze shows through the crack area...

The Georgies Jujube White glaze (bottle or catalog) said that you can add a certain glaze/colorant to it and it would make it a different color. Will have to try that! This one really cracked nice (and sharp).

The Arroya one went on like white glue and came out looking like white glue. Not surprised at that. Maybe it was too thin or likes shinier glazes better. Will have to experiment further with that one…

Three Black Underglazes and Crawl Glazes Test Tile Up-Close.

The very bottom tile (I enlarged it and put it right above so you could see the detail in the differences) the three black underglazes… How different can three black underglazes be - really? Hmmm - interesting!

Too Skinny with large surface area (warpage & cracking - but still ok for testing).

I don't know if you happened to notice or not some of the cracks in the tiles I used for these tests. I have a tendency to roll out slabs thin, texturing them makes them even thinner… I blame it on years of production of pendants, striving for thin, even pieces…  The intention for these tiles was to be test tiles, not actual tiles to be used somewhere. So I let them dry for a bit in between two pieces of drywall, but even that did not help the memory of the clay (see the warping on the left). The one on the right had a crack in it. Peeves had stepped as gently as a cat can on the drywall when they were drying, but I guess these cracks were so small they did not even show until after the bisque firing. Oh well - hope you don't mind too much. I don't… especially on such early tests.

If you want to search the previous posts I've made on Cone 6 Commercial Glazes, click HERE then scroll down the posts (most recent should be first).

So that is all I have for this glaze posting about the crawl glazes I have…
What experiences have you had? What have some of your tests looked like?
Oh, and look at the goodie I snagged not too long ago click HERE. I couldn't help myself (she may have more too if you want one to love…)

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