Making a new liner glaze (Calcium crystals)
If you have been following me for a while you’ll probably know that I am in love with a liner glaze commonly found in Susan Filley’s work. I think it is a calcium glaze that she uses as a liner; I am not sure tbh. This has inspired me to make my own. Of course this means I will have to get into using liner glazes in the first place. I work at cone 6 oxidation. This means that I will have to have boron to some extent in this glaze; Something I forgot in my first 2 tests. I won’t show you test #1 and #2 because they're absolutely monstrous. They did not melt whatsoever because I had 0 boron in them.
One thing has always bothered me about calcium based in glazes in general. Are they technically crystals? For the purposes of this blog I am calling the semi-matt alumina that develop, crystals… But… isn’t that what a matt glaze is?….. a crystal?…. Let’s not think about it too much. My main question is, how are we able to see the crystals without either some type of background or colorant added to the glaze? You don't need to add color to make the “crystals” (if that’s what they are) visible? The answer? …… You kind of can't. You see, Susan Filley’s crystals are only recognizable because she overlaps them with another glaze. So you kind of need something like another glaze behind it or you need to mix it with some other color and hope the white crystals are more visible. That's when it hit me…….
I've done this before! By total accident too!!! Do you remember when I made a blog about Matt crystal calcium based glaze? Before I thought they were titanium crystals but that's not what titanium crystals but now I think they are just a matt glaze with too much TIDI in them; I just didn't have the eyes for it back then. Here look, I still have the pictures.
See the little white dots?
Here is a better spread of them.
This was a test to make a matte glaze a while back that had 7% titanium dioxide in it. As a result I thought it was a titanium Crystal. Titanium crystals don't look like that. I think (and I am open to correction here) these are calcium crystals, the exact thing I've been trying to do. When I look at the recipe it has 0.7 molar amounts of calcium in the umf. Yup, that will do it. I'm pretty sure titanium crystals need some type of barium to even nucleate there crystals and I have no barium in this glaze. I know of two people that do titanium crystals and they were like “ yeah that’s not what titanium crystals look like, mate (one is Australian). keep in mind I have never experimented with barium I could definitely be wrong, please feel free to correct my hypothesis with your tests. I’d love to see them.
Realizing this I got straight to work developing three glazes; one of which I hope is a better version of The accidental calcium crystals you see above. I've decided to call the glaze, Antylamon. I ended up putting black under glaze on a few of the test tiles to give it a background just in case a few of them do crystallize. I won't be able to see white on white. All tests after this will put on a hold at 1800° f for 30 minutes after reaching cone 6 to promote crystal growth. If this goes well I should be able to put other colors to promote the same background without messing up the crystal growth. After about 4 tests I finally got one I am very happy with.
Here are the results.
Test #3
Sg : 1.43
application: 4 second dip
clay: laguna 16 porcelain
cone : 6 ox
This is a bit too thick, no hold, but i saw potential.
ok, I like this but I can’t see anything. How will I know if the alumina developed with no background?
At this point I realized I needed some kind of color. Like Susan’s work, I can’t see it unless I look reaaaaaaally hard. So i started to put mason stain in this base. luckily for me the glaze is prime for mason stains in that it’s calcium based.
calcium liner 3 + stain 60001 15%
Sg : 1.43
application: 4 second dip
clay: laguna 16 porcelain
cone : 6 ox
IIIIII love it.
No hold.
oo yeah, that’s what I’m talking about.
Look, I’ll level with you. I am not sure if Susans work is just a semi matt liner glaze or if I am allowed to call them crystal glazes on a technicality or what. What I do know is I made a good liner glaze for cone 6 ox that takes mason stains very well and when I put this glaze on a little hold where crystals grow…. they grow. I’m going to call this a success. I think after all this time I was just trying to develop a good liner glaze. The next step is to put it on a hold or add titanium dioxide to it to see what it does.
