Cleaning the pugmill

1. See hard lumps around edges

I've had the Bluebird pugmill for 3 years now. It's a 1999 model that I bought used. I don't think I would have been able to continue reclaiming clay without it because it was causing too much strain on my wrists. Now, I put all my clay through the pugmill and then give it a couple of wedging turns and I'm ready to go.

A few months ago I started to get hard (very hard) and dry (very dry) lumps in with my pugged clay. I could ignore these pieces while throwing but they would end up as sharp bits on the bottom of pots or as dimples on the sides of pots. I could remove them while throwing and then fill in the hole left, but this would invariably throw my pot off center, and who wants to be doing that anyway?

2. Barrel removed. Making a mess.

Melissa Schooley of Raging Bowl had the same problem, but from her blog descriptions, it was much worse than mine. Check out her saga with pugmill "barnacles" here.

3. Barrel off motor box

So, I decided that the first step I needed to take was to clean out my pugmill. Here's what I had to do:

1. Turn on the pugmill and let it run until it has pushed out all the clay that it will. Add 1 pint of water when running the last amount of clay to help lubricate the barrel and make removal easier.
2. Switch the pugmill off and unplug it.
3. Unbolt the nozzle end. Run a wire between the nozzle and the barrel. Remove the nozzle end and clean. In the picture (1) you can see the hard lumps on the outer edges of the clay, especially at the bottom.
4. Use pliers to release the spring from the rod in the vacuum chamber.

4. Chris power washing the barrel.

5. Unfasten bolts holding barrel to motor box and front supports (3).
6. Remove barrel and scrape clean.
7. Scrape blades and shaft.

Of course, you're going to make a mess, especially when you remove the barrel. Be prepared for this. I wasn't and got splatter all over everything (2)

The best way found to remove the gunk from the barrel and nozzle was with a power washer (4). Once you've got it as clean as it's going to get, work backwards and put the thing together again. At this point you're going to wish that you had kept track of the screws as you were taking them off! 

5. Cleaned out nozzle.

This is as clean as we were able to get it (5 and 6). The red stuff is the red clay that the previous owner used, it's not rust. But we couldn't get it off... it was almost like paint. You can see the pitted places where the hard lumps form. You can read more about this in Melissa's blog. Apparently there's some sort of reaction between the aluminum alloys of the barrel and the materials in the clay.

6. Cleaned out vacuum chamber.

I always put wet sponges at the end of the nozzle and over the hopper and cover the pugmill in many layers of plastic when I'm not using it. But reading the manual more carefully I noticed the following tip: "Periodically add a cup of water to the hopper and slot in the vacuum chamber." I am doing that regularly now. My theory is that if the clay is nice and wet it will not form hard lumps along the outside of the clay log. So far, so good.

Reycling Clay

 I love my pugmill! It has really made recycling clay so much easier.

This is how clay gets recyled in my studio. I reuse the bags that the clay comes in to line a bucket that sits next to my wheel. As I work all the scraps that don't end up in the slop bucket go into this bucket. Periodically, I empty the contents of the slop bucket into the recycle bucket as well to hydrate the dried clay. 

Once the bag starts getting heavy I know it's time for the second step. I line a cat litterpan with some of the dirty towels in the studio and pour the contents of the bag into it. I cover it up with other towels and slip the pan under the work table. It will stay there for as long as it takes (depending on the heat/humidity) for the clay to be dry enough to wedge. 

At this point, if I'm not ready to put it through the pug mill I cut it up into manageable pieces and put it in a plastic bag to make sure that it doesn't dry out too much. Then it's into the pugmill! And out come these great logs of clay that only require a couple of turns wedging and they're ready to go!