Pres
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Posts posted by Pres
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I guess all of you by now know that I use a Griffin Grip (GG) when trimming. Over the years I had used all sorts of trimming strategies usually on the wheel head, clay chocks, tapping in place, and rubber pads with a lid on top to hold the pot down. There were I am sure variations on these, but too long ago to remember. Back in the 70's though I started seeing references to a new tool the Griffin Grip. A few years later I had a little extra money in my Ceramics budget at the HS and bought one. After using it for a year at school, I bought one for home. Over the years It has saved me all sorts of trouble when trimming odd shaped pots like pitchers and others that required a thrown wet chuck, or a bisque fired one. Then I realized that with plumbing parts I could trim awkward pieces with more stability and have chucks that could be kept permanently to use, especially when making chalices or flagons(pitchers).
QotW: What sort of "trimming platform" do you use?
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I use 1/2 shelves in the bottom, sharing posts at the center positions. I have never had a downdraft blower before, and find that my glazes are brighter. That said, I wonder about the circulation using 1/2 shelves, better or doesn't matter? In the years before with the old kiln, shelf stilts almost never matched up vertically, and I probably broke all ot the rules at home concerning kiln loading, but got very tight loads with lots of pots. Had to take off top section ro reach the bottom and then put it back on to finish loading. Loved that old L&L, but baby sitting with a full load was rough on the sleep patterns! Now I load and forget, paying attention to the ap on the phone!
best,
Pres
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I have a 28" kiln where shelves are 26" half diameter. I make plates that are about 12-14" for patens in communion sets. I can only get 3 to a layer in a regular stack, but by using a broken shelf under two, I can get 4 of these to a kiln shelf. Does not seem like much, but in a load it means a lot.
best,
Pres
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Years ago, when I was working with glazes, I usually used tin oxide as an opacifier for white. Then as tin oxide became more expensive I started looking for different opacifiers for my white glazes going through the different -paxes and finding them not quite to my liking so I started using combinations of opacifiers for the whites that I liked as liner glazes. Then I played with adding rutile for a creamy looking liner glaze and a low percentage of cobalt for a icy glaze. HOwever, I have been wondering with the raise in price on glaze materials if others have found better solutions for opacifiers in their glazes?
Have glaze chemical prices forced you to make changes in your White glazes?
best,
Pres
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Like @Mark C., I have used a number of wheels over the years. I have found even in these later years that I can torque some wheels when centering for throwing off the hump. I also have not noticed much in the way of noise difference between 1/3, 1/2 or full. Years ago I used a Brent CX that was a gear drive, it was noisy! I throw on a CXC, and am using the original belts and have only had to replace a potentiometer when the shop got flooded. Over 20 years old now, but then I don't throw on it every day.
best,
Pres
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Great question, and as you see, there are reasons for different answers. I dip all of my test tiles, so the are the same on both sides. Then I use small shot glass type testers to see if the glazes interact with each other in weird ways. . . . why the shot glasses? Easy to throw off the hump, simulate a pot form and allows me to test inside and outside combinations. Finally if there are any weird interactions from different glazes that may cause the pot to crack, craze, shever or anything else, the shot glass shape is more stable and will keep the glaze from doing too much to the kiln. Lots of them can be fired as extras in any load.
best,
Pres
- PeterH, Magnolia Mud Research, Hulk and 2 others
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5
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When recycling clay for the ceramics classes before summer vacation, I would add a few ounces of vinegar into the pug mill. Over the Summer months the clay would set in 50gal plastic buckets with damp towels with a water vinegar soak in them. Every Fall the recycled clay was better than the clay direct from the boxes. Students noticed the difference and I did take the time to explain that the organic material in the vinegar had chance to age the clay with organic material.
best,
Pres
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QotW: How do you level the bottoms of thrown pieces?
I have been working on some chalices lately, trimming the bowls and the stems before joining and got to remembering how . . . . in the day I would use a needle tool to the level pieces up, whether the were thrown off the hump or on a other wise. In the first days of learning to throw I threw on the venerable Randolph motorized kick wheel with the cup heads where a plaster bat would fit for throwing. They were marvelous as the next day things would be dry enough to remove and trim and then move on. Then came working with metal wheel heads, and trimming of and removing the pots from the wheel or working on a wooden bat. Seems I always got things a little wonky and out came the needle tool to even small things up. Then at Penn State someone introduced me to the hack saw blade held perpendicular to the pot held by both hands to level the pot. . . Wow! To this very day, any throwing with leveling needed is done in the same manner. Double that if throwing off the hump, as I whip out 20 cups in an hour and worry about level in the trimming. Same works for plates as 12" of surface with a cutting wire is not always level!
QotW: How do you level the bottoms of thrown pieces?
best,
Pres
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I have made several vase forms that have 8-10 inch bases, and some bowls that have 12-14 inch bases. Presently I use a bat covered with a felt type rug with rubber backing. Using the wheel running slowly, with some dampness on the rug I can clean the surface of a foot ringed of flat form quite easily. The larger the bat the bigger the form can be covered. Two people holding the form should be able to make it work pretty easily using the weight of the form against the covered bat with the hands of the two individuals holding it steady. I use the same technique to clean the bottoms of chalices and patens for communion sets.
best,
Pres
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I have a favorite glaze that uses talc, and up until lately have had quite a bit to use in glazes that I bought several years ago. However this last glaze batch found me with none left. Last year I had heard about a shortage of talc, and believed I would have to reformulate my glaze to work with a different component, maybe dolomite. Imagine my surprise when I found Fabi Talc listed at SC. So I will be ordering some to use in my glaze. However, it makes me wonder if anyone has had to reformulate glazes or clay bodies due to a lack of materials?
QotW: Have you had to reformulate any clays or glazes due to a shortage of materials?
best,
Pres
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@ABlancBest bet here is to assess the kiln problem, fix it, and then re-fire the load to ^6. Check your elements to make certain none of them has broken first. If they are in good shape, then the problem is probably in the lead boxes. Is this kiln run on a cone setter or a programmable controller? If in a setter was the cone in the setter still as if unused?
best,
Pres
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Density of the load has an effect on the way heat moves in the kiln. Kilns are heated by 3 different forms of heat transfer: Radiant, Conduction, and Convection. Understanding these will help you to understand the need to pack the kiln consistently. Radiant heat is occurs first in the kiln as the elements radiate heat to heat up the air and the pottery. The pottery on the outer edges will heat up to radiate heat towards the center of the kiln. Please note that while Radiant heat is going on Convection is also occurring in the kiln as air heats up and begins to move to the top of the kiln forcing cooler air downward. Overly tight loads will inhibit the movement of air in the kiln causing areas that do not get air to not reach expected cones. However, as this is going on Conduction, where heat is moving through a solid, is taking place, Conduction is a slower process but it allows the pots to heat up from the outside to the inside, and the kiln from the inside to the outside. This good reason to have proper distance from the kiln to outside walls or other materials that could ignite.
Hope this helps to answer some of you concerns.
best,
Pres
- Min, Babs and Callie Beller Diesel
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@Gonepotty, could you include a little more information on your kiln. Are you doing a manual ramp with a kiln setter, or are you using a programmable controller. Balanced packing on all shelves will help with evening out the temperatures, so yes having a tighter pack in the bottom will effect the firing.
best,
Pres
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Hi folks, we covered this a few years ago, but I was mixing glazes yesterday with my plastic bucket sieve, and a brush to run the glaze through the sieve into a spare bucket, and then back into the rinsed out original bucket. I have often wondered about buying a Talisman sieve, but in the long run the cost scares me away, and I really get along fine with my bucket sieve. I will pick up a digital scale as the cost of them has come down.
QotW: Talisman, Bucket or other type of sieve for glaze mixing?
bestg,
Pres
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Welcome to the forum! You may do searches using the search tools in each strand area, or you may do a search in the main screen to search all areas for a specific question/subject.
Hope you get all the help you need to grow into producing for yourself and your grandchildren.
best,
Pres
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Couldn't help myself the other day. . . .I was at NCECA, and noticed a book cover I didn't recognize. . . looked closer and decided I needed a new book! It is another glaze book with Low, Mid, and High-Fire recipes. However, it sets itself apart by showing combinations of the glazes in 2 and 3 dipped coatings with rich photos of test pots showing the layers.Amazing Glaze Recipes and Combinations, Gabriel Kline.
best,
Pres
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I also "back fill" the joins at the bottom of handles also. Makes for a more comfortable handle and nicer looking bottom to the handle with the "visual return" to the pot form.
best,
Pres
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I'm sure we have had this discussion a few years back, but good to return to it for those newbies out there. Over the years I have used all three, and found that I prefer the Magic Water. When teaching HS in the early years, I had used slip as that is what I learned to work with. If you you were diligent about your scoring, and your paddling/compressing the seams along with regular gap filling and smoothing you would have a good seam with no problems. However, being lax in any way could leave a seam that would split, or leave and ugly hole to be noticed even after glaze firing. Students took a long time to discover diligence. Vinegar was the addition that I started adding to my slip containers, as the mild acid did help to work the seams better. However, I came to believe that it was too easy for students to cover up a bad seam with slip of any sort than to get the seam right. Along came Magic Water, and when I started using it myself, I knew that I had to start using it in the classroom. It did not change everything, but worked wonders with making seams and at the same time it was hard to hide a bad seam.
QotW: Slip, Slip with vinegar, Magic Water: What is your choice, and why?
best,
Pres
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You may find the book "Mud to Music" of help in your search.
best,
Pres
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A few questions here:
- Are all of the pots in the firing blistered as the one the picture shows all of?
- Is the pink glaze one that you have been using before?
- Is the blistering limited to the top third of the pot?
- Do you use a manual hold of any sort toward the end of your firing?
Presently my best estimation is gassing, as the pots do not seem to have allowed glaze gasses to escape. wiring the setter up, but cutting back on the power a bit to hold the temp may allow for the glaze to smooth up. I also wonder about the number of coats of glaze as the bottom of the piece looks normal for a gunmetal.
Others may have other ideas that may help you out, but this is . . IMHO
best,
Pres
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Hi folks, we have asked this question before, but it has been a while. Some of you may remember that I store my clay outside under my kayaks under a tarp. I have a platform that sits 4" off the ground and is 14'X2'. This allows me to stack a double row of 50# clay boxes 3 rows high that will hold almost 2000#. Obviously though, with PA weather often getting into the single digits this means the clay will freeze in the Winter to thaw in the Spring. I have tendency of wedging everything, and use the recycle clay in with the fresh clay.
QotW: Where and how do you store your clay?
best,
Pres
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A few years ago and older gentleman (bowling buddy) asked me to make him one to fit on his base as he had left the old bowl out in the winter. I have a plaster form that fits on the wheel that is a low dome about 20" across. I used a SC 630 at the time, and it did take me a few days to figure out how to make it right. I ended up throwing the bottom on the dome using a 2 inch thick slab that I pulled out to about 1/2 " with a foot ring pulled that was wide enough to fit over the base with allowance for shrinkage. I then made walls on a separate bat that were thrown cylinder raised 2 " and same thickness as the base. I attached the two pieces when leather hard and waited until bone dry before bisque firing. The first one I fired on the foot ring. . . .It cracked. The second I fired upside down no problem, and then fired the glaze on the base with glaze sponge cleared foot ring. He is still using this today as I have talked to him often, and he is very happy with the result.
best,
Pres
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QotW: What sort of "trimming platform" do you use?
in Int'l Ceramic Artists Network (ICAN) Operations and Benefits
Posted
I also hold my trimming tools with both hands, but I use the left hand to rotate the tool in my hand to the position I want instead of rotating the wrist of the hand holding the tool.
best,
Pres