The final step toward getting your wares table ready requires that you handle each piece individually to decide how to best clean it for showcasing. This one-on-one time allows you to discover each piece’s subtleties and beauty. Depending on the type of kiln and firing process you use, cleaning can take a few minutes, or up to several hours or even days. These finishing touches are important; cleaning a kiln load will help you more fully see each pot and better understand the overall firing results.
Tools and Techniques
It’s always a great feeling to have a fresh kiln load of work and an even better feeling when the cleaning is done. This is when you really get to know the pots individually and are able to see their beauty and flaws up close. The following tools (1) and techniques are a few ways that I’ve cleaned my wares over the years, loosely listed from roughest (or strongest removal) to finishing with mild soapy water. There’s no need to do all these techniques at once, or ever for that matter. I’m always learning about new cleaning devices from other crafts and have no doubt that there are stellar cleaning strategies and tools that aren’t mentioned here. These methods showcase a variety of tools and approaches as a starting point. Caution: Always wear a properly fitted respirator (see 2) and safety glasses when you’re grinding, chiseling, sanding, or creating dust!
Chuck It: Don’t clean something that you don’t think is worth the time. Too harsh? Maybe. But as the saying goes: your favorite pot going in to the firing isn’t always your favorite pot coming out. Sometimes, the best decision is to let a pot go.
Bench Grinder: These work great for grinding off large wads that are fused onto a pot. Green-stone and flap-wheel sanding are a great combination. Grinding produces a lot of dust, so I recommend trying to grind outdoors to mitigate dust in the studio. This is a fast process, so make sure you have good lighting or you will quickly discover (but not quick enough) that you have ground a divot into your piece.
Masonry Chisel: If you’re looking at a fused wad and can see that there is a good buildup of fluxed ash at the base of the wad, a mallet (or hammer) and small masonry chisel work great to remove it. Always angle the chisel just above the pot and chisel toward the center point of the pot. While this method is quick when it works well, the risk is that a piece of the ware could pop off with the wad.
Dremel Tool: This is by far the most frequent way I remove wadding and other crusty bits from the firing that are too big to be removed by sanding alone. There are many types of bits available, but the two I use most often are the ½-inch green grinding stone and the diamond wheel. The diamond wheel is good for cutting around the base of a wad and knocking it off, while the green stone grinds everything else. Note: A diamond wheel lasts longer if it doesn’t get red hot. When I use mine, I spray water as I grind, which keeps it cool and also keeps the dust down.
When you use your Dremel tool, make sure to take breaks. Depending on your tool or if you’re using a flexible shaft, you will experience varying degrees of vibration. Putting your hand through extended periods of prolonged vibration can result in nerve damage. If you finish using your Dremel tool and notice that your fingers are tingly, you have used it for too long. It’s important to take regular breaks to eliminate this issue.
Silicon Carbide: You can purchase a silicon-carbide grinding disk for your potter’s wheel that will eliminate any wobble on the foot of a pot. A handheld extruded silicon-carbide post or stone is nice to work on one or two high points independently. Silicon-carbide mesh powder works well for smoothing out lid seats. Sprinkle the powder into the lid gallery, along with a little water, and then spin or rotate the lid until it’s smooth.
Sharpening Stone: Similar to the silicon-carbide stone, a sharpening stone is great to clean off single high points.
Wooden Paddle: When you are trying to remove wads that are more stuck or if a lid seems to be stuck on a pot, sometimes all you need are a few gentle whacks with a paddle. When hitting your wads, hit straight down to avoid chipping the bottom. When trying to loosen a lid, don’t hit it right on the lip, which is the most fragile point.
Diamond Grinding Pads (2): These work similarly to sandpaper but last a lot longer. They come in many different meshes, but the ones I use most often are 120, 200, and 400 grit. There are two different versions of these pads: one that is thick and less flexible, and one that is thinner with a lot of flexibility. I prefer using the thinner pads because they’re easy to wrap around a pot.
Wet/Dry Sandpaper: Wet/dry sandpaper is actually silicon carbide. I use sheets in 120, 200, and 400 grit and sponges in medium and fine grade. I find the sponges work really well on edges. On a side note, I also occasionally use drywall sandpaper to help level out wobbling pots at the greenware stage.
Scouring Pad: For a lot of raku and pit cleaning, this is all you need. A good scouring pad with mild, soapy water will successfully clean the surface.
Mineral Oil: After all the grinding and sanding is done, I like to rinse off the piece, dry it, and then rub a very small amount of mineral oil on the surface. This deepens some of the colors and makes it presentation ready. The mineral oil isn’t permanent and will eventually wash off. Let it set for a couple of hours to a day before water rinsing your piece one last time.
Bowling Alley Wax: This low-gloss seal gives pieces a nice sheen. The resulting colors will darken some with application. Use a clean cloth to rub on the wax and then buff it out with a separate clean cloth. Note: This wax is not food safe and shouldn’t be used on pots you intend to use for food. It’s most commonly used on raku and pit-fired pots.
Photos: Tim Robison Creative and Abram Eric Landes.
Excerpted from Mastering Kilns and Firing by Lindsay Oesterritter, published by Quarry Books, an imprint of The Quarto Group. To learn more, visit www.quartoknows.com/books/9780760364888/Mastering-Kilns-and-Firing.html, www.amazon.com, www.barnesandnoble.com, and the Ceramic Arts Network Shop (https://ceramicartsnetwork.org/shop/mastering-kilns-and-firing). Learn more about Lindsay Oesterritter online at www.loceramics.com or on Instagram @alindsayo.