Yay! Maybe.... Or not?

After last week's post, I tried a bowl without the line decoration.
Let me know what you think!

I trailed a line of my matte glaze all around the rim, and love the way it ran on the inside, and how it blends with the stripes on the outside. I need to work on consistency in terms of applying my darker stripe, and clean up those black pin stripes - I need to get them thinner! I also want to do some fine tuning on the form, beef up the rim a touch, and improve the curve of the bowl. But otherwise, as for the overall shape, I'm pleased.

I'm also anxious to try this with a pale, apple green and a complimentary shade of blue? yellow? orange?. I was trying these early on in this testing series, and I'm almost ready to go back and try again. First, I need to head to the paint department of my local hardware store to stare at paint chips to help me narrow down which oxides to start playing with. But it may be a while before I get the chance to get there.

I'm excited and anxious about these stripes all at the same time. I have to admit, I feel like I'm being pulled in all sorts of opposing directions when it comes to trying all this new stuff with my glazes and my work. It's a little unsettling and even stressful to some extent. It's kinda like heading out somewhere without really knowing where you are going or how to get there, but hoping you make it there regardless.

And I still can't shake this urge to decorate. I wasn't happy with my trailed linework on the previous version of this bowl but I feel like this one is missing something. I'm not sure what exactly that means, and where that needs to go. Part of me just wants to go explore fabric stores, but with my schedule filling up, I can't see finding time for that any time soon. Maybe it's best to push it into my subconscious and let that part of my brain work on it for a while.

And as for all of my testing: you may recall, when I first began writing this little series of posts, I mentioned that I was currently exploring two different directions with my new line of work. These stripes have been one direction. Stay tuned to see where else my creative mind had been going!

A Minor Victory, But Sweet None-the-less

Problems in ceramics tend not to surface until your full-on into production. Case in point: my slate matte glaze.

I love this glaze. I hung onto if for a year, working out how to use it in my work. When my glossy sky-blue glaze struck a chord with the slate matte, it was full steam ahead. Or so I thought. Most pieces were fine. Made it from start to finish with no problems. But anything taller, with straight-ish sides was a whole different ball of wax. I was losing anywhere from 50 to 95% of these pieces in each kiln load.
That's a lot of garbage to be making, and honestly, I can't afford to make trash.

The problem? Large pinholes, or what looks like blisters in the glaze that had popped, the edges healed, but the center remained bare clay. On the smaller of these pieces, like my tall cups, there would be one or two of these blisters. Enough to ruin the piece. Larger pieces, like my large vases, would be covered. COVERED in these blisters. Not a pretty site.

So where to begin?

There's any number of reasons why a glaze would do this, so I just started moving down the checklist trying to figure out what the hell was happening.

Perhaps some organics left in the bisque were causing the problems, but a higher bisque didn't help. Still got blisters.
Moving on, perhaps it was gases swirling in the kiln? I checked my kiln vent, adjusted it accordingly but that didn't seem to help either.

Okay.....

Next thought: water vapour. Thinking wet glazes were casuing problems, I let them dry before loading my kiln.
Nope. that didn't work either.

Okay. Maybe it's from overfiring the glaze? It only seemed to happen on these taller pieces, which also occupy the top shelf of my kiln. Cones indicated my kiln was firing evenly so I tried going from cone 6 down to cone 5. Boy did that ever make the glaze ugly and flat. And the blisters persisted.

With firing things ruled out, I moved on to the glaze recipe iteself. Was there something in there that could be causing this? I sent copies of it off to trusted glaze experts, but they didn't notice anything out of the ordinary. The EPK was a bit high, in the crawling range, but I wasn't experiencing any crawling, and even substituting some calcined kaolin for the some of the epk didn't solve my blister problem.

At this point I was beginning to believe it was an application problem. And I'm not set up for spraying glazes, so that wasn't even an option.

I moved on to glaze additives. First up was some CMC gum. Perhaps the glaze was drying too fast on the ware?
Nope. That didn't help and just made things messy.
Ugh.
Next was some Darvan and sodium silicate. I thought, what the hell, but that didn't work either.

Now it's important to point out that by this time, my husband just cringed whenever it was time for me to open the kiln. It's hard making work when you have orders and deadlines, and you have to throw most of it away. Many kiln openings were accompanied with cursing and/or tears. But I'm stubborn and I persisted.

Chatting with a fellow potter at a show, I asked him if he added anything to his bucket of matte glaze. The answer? Epsom salts. The same epsom salts that ruined my clay body. I tsp per 10kg batch of glaze.
And bloody hell, if it didn't work like a charm!

Epsom Salts, or magnesium sulfate, is a flocculant. These help prevent glazes from settling, which I didn't think my glaze needed since it had so much clay in it. But apparently they also help with glazes used for dipping or pouring. I had come to believe that air bubbles were being trapped against the surface of my bisqued pot when I dipped it, and that they couldn't escape until the glaze was melted. But being a matte, the glaze didn't flow enough to heal the surface like a glossy glaze would. The epsom salts create a porous surface in the raw glaze so perhaps its easier for those air bubbles to escape before the glaze melts?

At any rate, I guess there's a couple of lessons I take away here.
- Don't put out a line of pottery to my wholesale clients until I have worked with it thoroughly first, to try and spot any problems.
-Ask for help. I have no problems with this. Many times I'll get answers that I have already tried, but there's bound to be someone, somewhere, who's done something I haven't thought of.
- and most importantly, never give up! If you want to solve those problems, you have to keep plugging away at them. Now, it's better to do this if you don't have the pressure of HAVING to get things done by a certain date (see the first point) but perserverence pays off!

They're BaaAAAAck!

Well, the last few weeks have been nothing if not completely frustrating.

So here I am, custom orders on the go, wholesale orders on the go, desperately trying to stockpile work for upcoming Christmas shows, frantically trying to replace stock that has sold at summer shows. I'm busy. VERY busy. And I don't really have time for things to fall apart.

But alas. It had to be...

Remember that problem I was having a while back with my brand-spankin' new pug mill? Where my clay was corroding the inside of the mixing barrel and pesky little chunkies were making their way into my pieces?

Weeeeeeelllll....

The pugmill manufacturer recommended that I add epsom salts to my clay body. What this would do, I was assured, was change the pH of the clay which would in turn, prevent all those pesky little chunkies from forming in my pug mill. Okay. No problem. 44 grams, dissolved in hot water, added to 25 lbs wet clay. Mix, pug, throw.

No problem, right?

WRONG!!! What a complete disaster. Have a look for yourself:





Yup. Three kiln loads and counting. Ruined.

After much crying, cursing, Clayart-ing and phone calls, here is what I learned:

Too much epsom salt can cause blebbing. As a piece dries, the salts migrate to the area of the pot that is drying the fastest (the rim in most cases). During firing, the salts will turn to gas and generally burn off. However, if there is too much salt, and the clay begins to mature before all of the gases have escaped, you will end up with what I have in the photos. Lots and lots of little blisters, all over the rims of a couple of thousand dollars worth of pots. As my luck would have it, my clay manufacturer ALREADY adds epsom salts to their clay. So by adding more, I overloaded the clay.

So there you have it folks. My advice: talk to your clay manufacturer before adding ANYTHING to your clay body. No matter WHO told you to add it.

Aaaaaaand in addition to that...

Those f'ing chunkies are back, busily corroding away at my pug mill.

Yup.

oh! And that would be the NEW version of the pug mill. The one with the corrosion-resistant coating.

Yup. My luck.