Continuing with my ash glaze tests! Starting out with just clay and ash, I did some button tests and some little bowls, mixing the invasive cattails, blackberry, and English ivy I helped remove with BC Wild Bird Trust at Maplewood Flats, and at Renfrew Ravine with Still Moon Arts during their land stewardship sessions last year. I decided to stick with the Ladysmith clay to reduce the number of variables.
The button tests are on Plainsman H550 grey stoneware and Plainsman H440 red stoneware, top to bottom and left to right: 100% cattail ash, 50:50 cattail ash and local clay, 70:30 cattail ash and local clay, 100% blackberry ash, 50:50 blackberry ash and local clay, 70:30 blackberry ash and local clay, 100% English ivy ash, 50:50 English ivy ash and local clay, 70:30 English ivy ash and local clay.
Then I made some little bowl tests on Plainsman H550. Left to right, 70:30 cattail ash and local clay, 50:50 cattail ash and local clay. 70:30 blackberry ash and local clay, 50:50 blackberry ash and local clay. 70:30 English ivy ash and local clay, 50:50 English ivy ash and local clay. The cattails seem to flux the best and make a glossy glaze without any crazing. Blackberry works too. The ivy seems like it behaves better with a higher ratio of clay? Next up, tests with some additional flux and silica!
I decided to focus on the cattails as they seem to be working the best, they dry and burn quickly, and there's plenty to be removed at Maplewood Flats. I decided to try various tests adding some calcium carbonate, nepheline syenite, G200 feldspar, or Mount Saint Helen's ash to the invasive plant ashes to increase the melt, and spent a lot of time on glazy looking for inspo and plugging in numbers to try and figure out where to start.
For anyone who's interested, Mount Saint Helen's ash was collected from an eruption of the mountain just across the border in Washington State in about 1980, and donated to me by Jay MacLennan at the Shadbolt Centre for the Arts. The chemical breakdown is available online and on Glazy so it's easy to plug into a recipe.
The calcium carbonate came from sintering shells collected from a local beach, and I think there's probably still a fair bit of salt in them, just to throw in another variable…
I didn't wash my plant ash, so I think that probably accounts for the fuming from soluble materials that remained in the glaze. And even though they were glazed right the way to the edges, some of them have crawled quite significantly, which I'm thinking is because the glaze was too watery?
Each of the pics show two different treatments of the same recipe: on the left the ash isn't sieved through a fine mesh and on the right it is sieved.
1. 40 cattail ash, 30 neph sy, 25 local clay, 5 calcium carbonate
2. 30 ash, 10 neph sy, 60 clay
3. 40 ash, 30 neph sy, 25 pioneer kaolin, 5 CaO
4. 30 ash, 30 neph sy, 40 kaolin
5. 40 G200 feldspar, 40 ash, 20 silica
6. 40 Mount St Helen's Ash, 40 cattail ash, 20 silica
7. 40 Mt St Helen's, 40 cattail ash, 20 clay
8. 40 Neph sy, 40 ash, 20 silica
9. 40 Neph sy, 40 ash, 20 clay
10 40 G200, 40 ash, 20 clay
I think the ones to keep working on are 1, 7, 8, 9, 10. And I'm kindof interested in 6?