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?
I'm definitely going to keep the big-runney feet on these pots. This is the result of overenthusiastic application of a oil spot glazes. I was told to make the pot really thin so that when I just kept piling on more and more glaze the whole thing wouldn't end up to thick. I guess on more vertical forms, one doesn't have to worry about the glaze getting too thick. Rather one just has to make sure you have enough kiln wash on your shelves.
Maybe with a little thought, big fat feet could be turned into a more guided and artistic process.
If you like the kinda stuff these people sell, its very high quality and about half the usual price. I take about 20 g of their D-ribose sugar every day. It massively improves my energy level. D-ribose is a weird non-dietary sugar that the body manufactures to make adenosine triphosphate, DNA and RNA. It has zero metabolic calories.
If you like your digital scales, you might post the links where one can buy them.
I started out with the dial o matic because a couple of years ago when I was beginning to fit out my pottery studio. I was advised that the digital scales were sometimes inaccurate and I would be better off with the triple beam. I wished I had originally gone with the digital now because of how much faster they are to work with.
I buy a lot of "Chinese junk" off of eBay and a little at Harbor freight. Most of it is quite well-made and extraordinarily cheap.
Harbor freight is a very clever distributor. The exact the stuff I see on eBay clearly from China, They rebrand as Chicago Pneumatic, Pittsburgh Power Tools etc... ..good stuff we trust made, in America (spelled China) right from of the Rust Belt. . Whoever said , "the truthful over" was a blind ideologue.
I really like the double hanging knob pot. I have two bench grinders. I've never been hesitant to use them, until now.
I've attached a couple of pictures of the pots I'm talking about that have really serious big runny feet. Please excuse the primitive photography but I'm so new at pottery, I haven't put together a good glare free photo box yet. From these photos, it is hard to see the patterning of the feet and how it works with the pot.
Thank goodness I use tons of kiln wash on my shelves.
I just finished reading this book. I thought others might enjoy it.
It is an articulate synthesis of the theory of aesthetics.Though the author uses architecture for concrete examples, it is equally applicable to any form of art, including ceramics. It greatly clarified my thinking about design
Dipping or spraying doesn't matter if everything else is right. I double dip every pot I make. But if the glazes are too thick they'll peel off. If the surface cracks like dry mud as the glazes dry, they're too thick. I keep my glazes at a creamy chocolate milk consistency. First dip gets a 6 count, second dip gets 4.
I disagree. The difference is extreme and it matters a lot. Layering 5 or 6 glazes on a pot with a spray gun is easy. Layering that many by dipping and you'll either have the glazes peel off (if you're lucky) or run off when fired.
Doc, I think you should bite the bullet and spray. When I'm doing test tiles I use an airbrush. It has a little cup on the side that rinses out quick and easy and is almost as easy dipping plus I have accurate tests instead of test that have little in common with the actual application.
After doing some tests, I agree with you. If you want to know what it glaze will look like sprayed, you have to spray it. Sometimes dunked test tiles looked nothing like the sprayed glaze. Thanks for the salient advice.
Thanks the link to the Stephen Hill Specials. They look good.... so does Surface Techniques of Steven Hil.
My cheapo Chinese guns look amazingly similar to the Stephen Hill Specials. I started by boring out the orifices. That seems to work quite well and still produces a nice round spray pattern. And heck, for less than $10 they are worth it for throwing at the next dog barking too late at night