Attached are some more pictures of the slab roller. They're pretty self-explanatory.
The strap metal is 1 1/2" by 1/8" and 1 by 1/8"
Turning a wing bolts adjusts the thickness of the slab.
The cord is nylon clothes line.
In the stirrup picture you will see 2 stirrups. I usually only use the bottom one but if I'm pulling a very long slab I will have to also step step on the higher one.
One thing that may not be clear from the pictures is that the top of the bungee hooks into a loop in the top of the rope so that it pulls down and thus pulls the back sheet of canvass up when you remove your foot.
The 17" wide rollers are from a junked package moving conveyor that the local post office scrapped and it ended up in at my scrap metal recycling source. They have PVC tube slipped over them and glued to make them a little larger.
The scrap metal and rollers were purchased at $0.35 a pound and weigh about 10 pounds total
The canvas was about $10 and there were assorted bolts and nuts for about $4.
Judy asked if different canvasses could be swapped out. If you put hooks vs just tieing the canvas to the rope, it would work well..
The basic idea of this roller could be adapted in many ways and sizes.
I tried Peters drop lid making technique. I could never get the clay centered enough on the hump mold.. So I extended the idea a bit. I put three small countersink bolts from the bottom of a plastic bat,. 1 on center and 2 of them about 1.5 inches out from center. Then I made a series of hump molds on top of that bat (so I was sure the pin holes were lined up), similar to Peter's, for different size lids.
You can put a slab of clay over it or just a lump on top to center and shape.
This gadget makes very thin, even lids quickly. The thing I like best is that you can add knobs, and decoration in the same operation.
attached is a picture of a technique that I use that seems very secure.
I use heavy music wire with an 80° bend on each hand which slips into small holes in the plate. These holes can be very small and less than an eighth of an inch deep works fine. Just make sure you bend the ends of the wire so that the weight is resting on the point at the end of the wire. When I plan ahead, I put these holes in the greenware..Sometimes I forget. Then I to use a small diamond drill To make them.
Thank you for some very helpful and creative strategies.. I'm going to give them a try.
I wrote Sarah and this is what she said
"I leave the exterior of the pieces in their natural colour and just spray the colour onto the interior of the bisq pieces very carefully. Any overspray I clean off by hand. I don't use glaze but hand mixed terra sig colours; definition is much harder to achieve with glaze."
Attached is a picture of a cheap in "envirovent" that I built for my km 1227 Skutt. It slides underneath the kiln and the little spring pushes it up against the bottom of the kiln to form a seal. Enough cool air leaks around this interface to keep the exhaust gases cool. I use the rheostat to control how much suction it produces. The whole thing cost about $40 With all new parts from the hardware store.,
I'm not sure how much suction I really need but I tested by holding a butane barbecue lighter flame above a quarter inch diameter hole in the lid.(Courtesy of the prior owner of the kiln). If the flame is strongly pulled into the whole I assume that's enough suction, but I'm not sure. Advice on this point would be appreciated.
for throwing, I use a five wheeled secretary chair that has a small springy back. I have a stiff wire coming forward from the frame that has a loop on it. I made a stiff wire hook on the front of my wheel frame.
When I'm centering and need to have my rear planted solidly, I hook the wire on my chair to the hook on the front of my wheel. At all other times, I unhook my chair from the wheel.
This allows me to to roll around short distances to grab tools etc. The flexible back of the secretary chair gives me support in a number of positions without restricting my movement.
Orton sent me the latest version of their cone calculation software spreadsheet. Since it's not yet on their website, I thought others might like to have it now. Here is a link that you can download it from
The hard part of throwing your own ball mill jar is getting it perfectly round. I found a way to throw a very round ball milling jar.
On the base of your giffen grip, with the fingers pulled way out, throw a thick walled cilinder little higher and slightly smaller in diameter than you want to end up with. Get a piece of PVC tubing with an ID the diameter you want the OD of your jar to be and a little bit taller than you want your jar to be. Make sure you cut one end of it very square. I used an 11 inch ID pipe.
Slip the pipe over the cylinder you pulled and crank your Giffen grip down on it. Reach into your cylinder and pull it out against the inside wall of the pipe. Then you can reach in and collar the top down to the size of one of those plastic sewage pipe clamps that has a gear clamp around it.
Cut the jar with the tube off of the giffen grip and set it aside for a few days, It will shrink away from the plastic tube. It is then easily removed for further drying.
Mine turned out perfectly round and could pass for a commercial model.
Sometimes I have more fun solving glaze and throwing problems than creating pretty pots. Once I get something to work well, I usually lose interest in it. I'm not inclined to reproduce that item, but then of course, hobbyist versus a production Potter.
Learning from failures requires extensive data collection so you can understand that caused the failures. No data, no learn. I have a database that allows me to take pictures of of everything I do after glazing and after firing, with extensive notes. When something goes wrong to this provides a lot of clues to solving the problem.
Lately, I've been running many hundreds of test tiles to try to get a better pallet of glazes. This approach is been invaluable in sorting out what works and what doesn't. Some days I think test tiles are my art.form.
I agree with everything you said up until last phrase, " look the kid in the eye and tell him not to try to get something over you again." if you're not careful many kids will see that as a challenge, "throwing down the gauntlet". You don't want to set up some game or challenge. you want to pay as little attention to inappropriate behavior as possible. However, a confrontation can underline it because it implicitly says the kid has gotten to you emotionally, which is a reinforcer.
When sanctioning kids you have to be very careful that you're not at the same time socially reinforcing the behavior that you're trying to stop. Almost any dialogue you, the high status person... The Man, have around inappropriate behaviors can actually reinforce the behavior even though your content is negative. Adults are too quick to explain things to kids that they already know on the assumption that the misbehavior is because of lack of knowledge. The implicit assumption is that at some point the kid will look up and sincerely say "Mr. Jones I'm so sorry I didn't know we weren't supposed to make bongs in here. I won't make any more". If you are not adding some truly new information, your interaction with them is likely to be acting as a reinforcer of the very behavior you're trying to suppress. Also adolescents males like to mess with "the Man", to see if they can push the dominant male off the top of the rookery.
However, you want them to know that they are not successful at flying under the radar. This means that you have to communicate with them, but maybe not personally. My recommendation would be at the beginning of the first day of class make a clear announcement about what the rules are about making paraphernalia etc,, so no one can say "I didn't know."
When you load the kiln anything that you deem inappropriate, note the signature then drop it in a barrel so that it breaks. No, you can't be sure it is what you think it is. But it's your job to make that call, and it's their job not to put you in a position where that's a tough call. They do so at their own risk.
Put the barrel of broken pots someplace near where the students enter. At the beginning of class, in the very unemotional matter-of-fact tone say something like, "when loading the kiln, I noticed a number of pieces that in my judgment were inappropriate. They are in the barrel over there. You are more than welcome to retrieve them." Then say no more. Repeat as necessary.
Which "red iron oxide" you use as a raw ingredient makes a huge difference in whether a red iron glaze comes our red or brown.
If you stay below cone 7, the red iron oxide you start off with is pretty much the red iron oxide you'll end up with. Fire the glaze hotter and longer, and you'll end up with black iron oxide which has to be converted back to red iron oxide during the cooling phase of the firing.
Using a synthetic red iron oxide with a large particle size will result in a large amount to red iron oxide crystals for free iron to form onto. Using a small particle size red iron oxide at higher temperatures may result in a complete degradation of the red iron.
Synthetic Red Iron Oxide is made with Iron Sulfate crystals, which is nearly 100% pure due to the crystallization process - crystallization is a cheap way to purify something. These green crystals are then fired with oxygen creating a Red Iron oxide of 98% purity or better.
This is a photo of US Pigment High Purity (synthetic) Red Iron Oxide and Laguna Clay Red Iron Oxide. Although they look almost identical, the Laguna product fires brown while the US Pigment product fires red.
Here's Richard Busch Nutmeg made with three different types of Red Iron Oxide:
Laguna Red Iron Oxide
US Pigment High Purity Red Iron Oxide
Prominsa Spanish Iron Oxide (sold by Laguna and many other vendors)
The difference between Promindsa Spanish Iron Oxide and Laguna Red Iron Oxide is less subtle.
Doc, are you using 15% RIO in the Readers Digest? Mine comes out a lot darker. Your gold color looks better.
Where does US pigments natural iron oxide fit into this?
I agree with that I agree that one needs to be picky about one's glaze Ingredients, but how do you know where the best ones are? You think a company like Laguna would not be supplying second-rate materials, but obviously they are. I know you can run tests on everything, but that would be an overwhelming task. At some point you've got to figure out who you can trust and who you can't. Can we make a list of quality suppliers? If I understand right, we can put US Pigment at the beginning of that list. Who else can we add?