Seaweed pinch pot

Seaweed pinch pot

Saturday, 5 October 2013

the web, my great teacher

A couple of steps forward in expanding my ceramic surface repertoire! Thanks to the internet and the generous ceramic folk who share their wisdom here.

Firstly, I am feeling very grateful to NZ potter Peter Gregory for sharing his high fired glaze recipes. I was especially excited to find Peter's glaze page because many (most) of the glazes he details are fired in his electric kiln with good results. Until now pretty much all the glaze recipes I'd found on-line were for reduction firings, and I rely on a firing service with only electric kilns. I have made up a couple of Peter's recipes - his 'buttermilk' and also 'black tenmoku'.  The above examples show buttermilk on the outside and the inside has the two glazes layered (buttermilk on top of tenmoku).

I'm enjoying the dappled and streaked effect of this glaze combination but not sure about this on the inside of a tea/coffee cup ... maybe a bit too close to looking mouldy or like curdled milk in your tea? (thoughts, anyone?) On the outside of a cup might be better, but I'm hesitating because it looks like it has run down the inside quite a bit (I dread the shame going to the 'work to pick up' shelf and finding mine is the work still fused to the kiln shelf!). A small test to the upper part of the outside surface... yes, that'll be the next of my seemingly endless experiments. (Oh and I did also try the Tenmoku on it's own but wasn't so keen on it - a bit too glossy and not as black as I'd hoped... maybe I need to have it thicker to get a better result).

Speaking of experiments and on-line learning resources, another recipe I tried out recently was for a coloured wax resist. I get the Ceramics Arts Daily email updates and I reckon I pick up a couple of good snippets of information each week from looking at these. A couple of weeks back they had something on resists including a coloured resist recipe involving iron oxide, cold wax resist and Gerstley Borate. You can see the results of my experiment with this on the three pieces shown below (also featuring above-mentioned glazes). I'm really taken with this. The only problem I'm having is getting some sense of control of the brushwork - it's quite tacky and I can't seem to get a nice smooth brush line, even a thick one. I had hoped to be able to use it for finer detailed work. I think I'll try some different brushes, and thinning down the resist. It wrecks the brushes though.

Be sure so check out all the other clay action on Mud Colony this week!


  1. They look great. Kind of see what you mean about the curdled milk ... You'll just have to try them out with various contents and see! What if you mask off most of the inner surface and just have this molten effect on the upper third or something like that? And I reckon the resist lines look lovely in their loose uneven state, especially the lines around the beaker, with specks of glaze left behind.

    1. Thanks Georgia! Yes, I was thinking along the same lines with trying just the top third of the outside. Will give that a go soon. By the way, I did end up trying re-glazing a few old pieces, as per your suggestion from several weeks ago - so far I've just tried covering a very milky 'clear satin' with a clear gloss, and was pleased to find that this layering did increase transparency as I had hoped! Now I'm assessing all my former glaze 'failures' for second glazing possibilities (although many pieces aren't worth the effort). Great to have your input!

    2. I've found some things that don't seem the effort turn out heaps better than I'd expected when refiring, maybe because I'm less precious about them in the first place. I can get a bit nervous sometimes when refiring if there are areas that already look ok, as I might lose those good effects. But if something is a total dud then there's nothing to lose! (Except the time/ glaze/ cost of firing etc ...)
      Anyway ... I wonder if you will get the same curdled effect with those glazes on the outer surface? I'm finding that glazes often behave very differently depending on whether the surface is concave or convex. Will be interesting to see!

    3. Your layered glazes would be spectacular on the inside of a large fruit bowl. I would happily drink tea from your bowls.

    4. Hi smartcat - a large fruit bowl is a great idea, I think you're right that the glaze would look good there. I have to build up my throwing skills to that scale though... might be a bit of a way off yet, although I've never tried, so who knows... maybe I have more muscle than I realise ;-). And nice to know you wouldn't find it too off-putting for tea either! Thanks.
      And Georgia - you are so right about good experiments happening when your less precious about things. I guess I was more thinking of the underlying form having to have some appeal to make it worth the time, but even when that is questionable it's all a good chance to just test stuff out. Good to be reminded of the value of duds!

  2. Hi Nina,
    I am so pleased that the page I have on high fired glazes is helpful to you. It is a real pleasure for me to see the glazes in use.

    The layering of glazes such as buttermilk over the black tenmoko glaze adds a whole new world of possibilities. Frequently such combinations do move or flow more than the glazes on their own. One thing you might consider doing to protect kiln shelves is to make some simple glaze catching saucers to put under pots where you suspect there might be risk of something running. If you make some that are about two inches wider than the foot of the pot (so as to give you about an inch all round the outside of the pot), and have a rim that goes up about half an inch to an inch high, then they will provide great protection against spills. Bisque fire the glaze catchers before using them. To help you release the pot from the glaze catcher you could also give them a good thick coating of kiln wash on the inside, or make up your own from a creamy mix of calcined alumina hydrate or calcined china clay, and a little ball clay added to help it stick. 500 gms of calcined alumina to 50 gms ball clay, and enough water to make it creamy is what I use.

    You can calcine alumina or china clay by putting a pile of it in a bisqued bowl, and including it in an ordinary bisque firing. This removes the chemically bound water, and prevents it shrinking and cracking when applied to your glaze catcher.

    (hope the glaze catcher description makes sense, let me know if not, and I'll put some information and photos on my blog)

    When I do crystalline glazed pots I have to put a glaze catcher under each one. I also make a stand for the pot to sit on in the catcher. The stand can be a little thrown ring of clay that is matched to the same diameter as the foot of the pot. The stand stops the foot of the pot "drowning" in the large quantity of glaze that will run of a crystalline pot in its firing.

    Whilst I do formulate some of the glazes that I use from scratch, I also make use of other potter's recipes. The collection of glazes that I have on my site are ones that I find helpful to me, and they are not necessarily my own (If they are not, I try to credit the source where I can. Buttermilk is from John Britt's "The Complete Guide to High-Fire Glazes", and BTM is a glaze I have "inherited" from another potter, and origins buried in the mists of time!). In most cases, I will adapt recipes to my own use, and will substitute materials to what I have available here.

    Anyway, sorry to do such a long comment, but I hope the information is of some help. I do like the pots that you are making, and the coloured resist decoration is full of promise too!

    Best Wishes, Peter

    1. Hi Peter - thanks so much that additional information about glazing and making glaze catchers. I think your description is very clear and I'll try to follow your suggestions when I get a chance. I can't thank you enough for taking the time to pass on your ceramics wisdom - it really is such a boon for someone like me whose trying to build up skills and knowledge without formal ceramics education.
      Thanks also for your encouraging words about my work. Hopefully there will be much progress made in the coming months/years!!
      Thanks again and all the best.