Tuesday, July 25, 2017

Recycling a Large Batch of Clay without a Pugmill

wedged clay is nearly ready for bagging (after days of work)
Over the years I've tried to recycle clay regularly in my studio, but I haven't been particularly consistent. In 2014, I paid a studio assistant to help me clean and recycle clay in the studio, but I haven't done so since.

step 1: drying semi-dry clay chunks in the sun

My Usual Approach to Recycling Clay at Home:

My more typical approach to recycling clay is to recycle in small batches several times a month. I keep a slake bucket going in the studio. I add bone dry clay and throwing scraps to water. The bone dry clay slakes in the water and becomes wet clay again. After I have accumulated enough wet clay, I scoop it out of the water and let it dry in trays or shape it into arches to dry a bit faster.

step 2: breaking up dry clay into smaller pieces

After the wet clay has dried sufficiently, I wedge it in small batches at my wedging table and then either build with it or store it in bags for later use. This method is tedious, takes up precious studio space with drying, slaking, and drying clay again, and also tends to result in mottled or marbled clays if I try to mix more than one type of clay together. If I don't mix clays, I have to keep separate slaking bins and drying trays for each clay type I use.

step 3: spreading out dry clay in the pool; step 4: wetting dry clay

Recycling Clay at School:

At YVC we have an large mixer and a pugmill we used to recycle clay. These tools make mixing much less physically demanding and much faster, but fit into a large studio better than a home studio. A mixer processes fairly large batches of clay; a pug mill processes smaller batches on a regular schedule. I can't use a mixer at home without investing more space and appropriate ventilation. I also don't (usually) need to recycle much at a time. I wouldn't mind having a pugmill for recycling, but the cheapest I've seen is about $2300 and a pugmill takes up a significant amount of space relative to my small studio.

step 5: mixing slaked clay (and making sure all clay is slaked)

The Problem:

By the start of this summer, I realized I had let my dry studio clay collection get a little out of hand. It was taking up too much space in my studio, and I didn't really know what I had where. I started brainstorming options other than recycling all of it by hand. I considered a pugmill to be too expensive and couldn't really donate the clay to YVC because much of my clay is low fire and would cause problems in the studio, even if kept separate. I considered just tossing it out, but that seems wasteful--even if new clay isn't that expensive and would save me time.

step 6: mixing wet clay pieces into slaked clay slurry

The Solution:

While laying in bed one night, I got thinking of how we walked on clay to "recycle" it at the school studio in Japan. At the time I thought it was a bit silly, because we were clearly walking on store-bought and well-prepared clay and the use of our feet wasn't really an improvement over the use of our hands. But in my current studio, the problem was recycling a bunch of different clays and a pretty big quantity of clay overall. That I have so many clays is silly, but they've accumulated over the decade. I've bought clay at Clay Art Center in Tacoma (when my mother-in-law has lived nearby), and at Seattle Pottery Supply (again, when my mother-in-law lived close), and at Archie Bray when I took a workshop there. I've used low fire clay and mid fire clay for different projects (The Archie Bray workshop required cone 6 clay when I'd been using low fire), and people have donated clay to me. The total adds up to at least 8 different clays, as far as I can tell, including low fire, porcelain, stoneware, groggy, and red clays.

the clay slurry is fairly even but too wet

Getting Ready:

The longer I thought about it, the more fun a large scale, messy, foot-wedging solution appeared. And, I could take care of all the clay in one fell swoop. So, I collected all the various bags and containers of bone dry or mostly dry clay from around the studio, set the slightly wet clay out in the sun to dry, and proceeded to break apart the dry clay with a hammer. It took about 3 days to collect and dry all the semi-dry clay from around the studio. My family laughed at me as I found more and more partial bags of clay in various nooks and crannies.

leftover hand-wedged clay with marbling of different clays (and that pesky porcelain chunk near the top)

Once all the clay was bone dry and had been smashed into smaller pieces, I got out my daughter's kiddy pool and spread the dry clay around it. I added water over the top of the bone dry clay and left it to slake for the day. By afternoon, most of the clay was slaked. I mixed it up a bit and made sure the dry clumps were covered with water. By evening, all the clay was slaked. My daughter was excited to get in, so I let her walk in the slaked clay. By walking in it, she was able to further smash some of the clumps of clay that were still semi-solid. I had some wet, but not wet enough clay leftover from previous recycling attempts (this clay was marbled from different clays mixed together, but not well), so I cut that up and buried it into the slurry to be mixed the next day. 

step 7: wedging the slightly dried slurry with the power of many (little) feet

The Fun Part:

The next day I invited some friends and their kids over to our house to walk in the clay. The kids had fun and got very messy, and maybe wedged some of the clay in the process, too. I had a bucket of water and several large sponges ready to deal with their dirty hands and feet. I didn't quite anticipate how dirty their bellies and hair would get, but the bucket worked fairly well for that, too. 

bonus step when kids are helping: a bath in the water bucket

As the kids lost interest, I got into the pool and used my own feet to wedge. At this point I stopped taking pictures because cleaning off the kids had completely dirtied my hands. The kids are all pretty small, so they didn't have the weight, strength, or balance to systematically foot wedge the clay. My friend and I were able to walk around the pool systematically, making sure all of the clay was worked evenly. My other friend scooped clay from the sides of the pool and piled them in the middle. This was a particularly helpful part of the process that I hadn't considered, because it mixed clay from different areas of the pool together more thoroughly.

step 8: foot wedging the clay again after it has dried for several hours

The Finishing Work:

The clay was still pretty wet and sticky at this point, so after my friends departed, I left the clay outside in the sun until evening. In the evening, my daughter went out to stand on the clay and I noticed she no longer sunk into the clay. The consistency was much improved, though a bit wet, still, underneath the surface. We ended up scoping the clay from the sides of the pool and piling them in the middle. My daughter needed to jump to make a dent in the surface, but I could stomp on the middle pile and mix the bottom clay and the surface clay. We smoothed the surface of the mound and left it overnight. 

step 9: piling up the clay to mix the different layers together

In the morning I was able to cut off large blocks of clay, shape them a bit and bag them. I made up four bags of clay, not quite as full as when they come from the clay supply companies. I figure I bagged a little under 100lbs (4 bags of not quite 25lbs). The middle and bottom of the clay mound was still too wet by afternoon. In the evening my daughter and I foot wedged again and so far this morning I have bagged close to another 100lbs.

step 10: using gravity to wedge on the cement sidewalk

The process is exhausting, particularly when it is hot outside. Everytime I have foot wedged, I have ended up drenched in sweat. Today's pile of clay is harder on the outside than inside and has more air pockets than the top layers did, so I have taken to wedging the ~25lb chunks on the cement ground where I can let gravity do most of the work. I took a break after just two rounds of this type of wedging because it is exhausting and I didn't want to hurt my back by lifting 25lbs over and over again with poor posture.

step 11: cleaning up the mess on the patio, cleaning out the pool, and cleaning all the tools and buckets. this step has not yet been completed

I am almost done with all the clay I had to recycle. The first 4 bags were fairly even in consistency and how well mixed the clay was. I can't see any marbling of clay colors in the first 4-6 bags, but there are some sections that are drier from being more exposed to the outdoor air.  In the last few bags I can see some marbling where the clays didn't mix as thoroughly and there are some air pockets as I cut the clay off of the center mount. The consistency is still probably better than mixing multiple clays together by hand. Hand-wedging (or gravity wedging) the last bags of clay probably makes them good enough for hand-building--if not throwing. Overall, this food wedging process is time consuming, tiring, and makes a huge mess, but I think the result (and certainly the speed of getting all that clay done at once) is an improvement over wedging by hand. And, of course, I saved myself $3000 by not buying a pugmill.

feet stay cleaner when the clay is drier.

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