PeterH
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Posts posted by PeterH
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1 hour ago, Min said:
I was wondering about the consistency of the frothed glaze and how it might change the application.
I suppose that it's just possible that some form of froth flotation is occurring, separating out some particles from the mix. It's certainly a technique widely used in mining/ore-extraction.
https://en.wikipedia.org/wiki/Froth_flotationA hint that silicon carbide might be a candidate for this sort of extraction from silicon/silicates.
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49 minutes ago, Taylor Crowell said:
I found my controller flashing "PLOG 134". My manual says PLOG is a diagnostic error that can usually be corrected with the enter key.
Looking at the manual on Orton site (via https://www.ortonceramic.com/autofire-controllers-resources)
I don't see a PLOG 0134 message mentioned, if you can't find one either it might be worth contacting Orton to find out what it means.
However, with the exception of PLOG 0011, they all seem to imply a pretty significant problem has occurred. Hopefully simply as a consequence of a transient such as a power glitch.
PS Pedantically the manual says that the error can be cleared. As you seem to have confirmed this doesn't mean that you can [always] just continue with the firing [well spotted].
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9 hours ago, Retxy said:
my needs: cone 06-04 glazes that don't craze. my hopes and dreams: cone 06-04 glazes that are utilityware safe. my pipe dream in the sky: strike it rich and go back to cone 6 firings so I don't have to worry so much that the body below isn't vitreous.
Sounds like a very rational analysis. It might be worth starting a new thread asking for recommendations of body/glaze combinations likely to meet those criteria.
PS Have you seen these discussions on glaze chemistry at Digitalfire. (Not recommendations, just low-hanging google fruit.)
G1916Q - Low Fire Highly-Expansion-Adjustable Transparent
https://digitalfire.com/recipe/g1916qG1916M Cone 06-04 Base Glaze
https://digitalfire.com/article/g1916m+cone+06-04+base+glazeG3879 - Cone 04+ UltraClear Glossy Base
https://digitalfire.com/recipe/g3879
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1 hour ago, Crooked Lawyer Potter said:
I draw 50 ml of the terra sig into my syringe and weigh it. It weighs 70 mg. I subtract the weight of the syringe (28mg) and then double the number, as in:
(70 - 28 = 42) x 2 = 84
Can you repeat the measurement process again? Once with t-sig and once with water?
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Can we check your figures, as SG<1 seems rather unlikely.
What are you measuring, and what where the values?
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How are you measuring the SG?
I've read several times that you cannot/shouldn't rely on hydrometers when measuring slips (i.e liquids with complex rheology).
If you did use a hydrometer can you recheck using a syringe and scale?
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I'm uncertain what types of glaze you are interested in, which influences what "chemistries" you will need to know.
For example are you interested in vice-free "reliable" glazes or those with "character"?
Which might mean a choice between:
- a liner glaze and one or more base-glazes that you can colour to taste.
- several different glazes with radically different properties and constituents: e.g. oil-spot, crackle, "wood-ash", ... -
You might also find the second half of Ian Currie's book Stoneware Glazes of interest.
https://wiki.glazy.org/t/ian-curries-stoneware-glazes/367.htmlIt discusses the constitution of a variety of "classical" glazes. Which might be considered to occupy some "sweet spots" in interaction space.
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3 hours ago, Retxy said:
because these older out of prints are very spens
You might try www.bookfinder.com, it's quite good at finding both old and new books. The later are sometimes surprisingly cheap.
I bought copies of the 1st and 3rd editions if "Parmalee" back in the 1980s. The latter is IMHO vastly superior, being "completely revised and enlarged" after Parmalee's death by a colleague Harman. Change this search to your postal region and currency. https://tinyurl.com/yv5dfyfx
I thought it was a great book at the time, but it's certainly not where I would start learning now.
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I found this page instructive: https://digitalfire.com/picture/huctibegac
This chart compares the decompositional gassing behavior of six materials as they are heated through the range 500-1700F. These materials are common in ceramic glazes, it is amazing that some can lose 40%, or even 50%, of their weight on firing. For example, 100 grams of calcium carbonate will generate 45 grams of CO2! This chart is a reminder that some late gassers overlap early melters. That is a problem. The LOI (% weight loss) of these materials can affect your glazes (causing bubbles, blisters, pinholes, crawling). Notice talc: It is not finished gassing until 1650F, yet many glazes have already begun melting by then (especially fritted ones). Even Gerstley Borate, a raw material, is beginning to melt while talc is barely finished gassing. And, there are lots of others that also create gases as they decompose during glaze melting (e.g. clays, carbonates, dioxides).
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5 hours ago, Ben xyz said:
Appreciate the correction in my math - the Marilee recipe was asking for 3.4 (not 7).
6 hours ago, neilestrick said:I've had glaze lava with less than 1/2 of 1%.
I think that there is some confusion/disagreement on the amount of SiC in Marilee’s Lava, possibly due to a historic typo.
Glazy gives +0.34 https://glazy.org/recipes/24043While this paper gives +3.5 https://www.thestudiomanager.com/posts/tag/lava+glaze
Many recipes list the silicon carbide in this glaze as 0.34, but I’ve seen enough others arguing that was originally a typo many years ago, so I went with the 3.5% recipe. -
You might find something in these ...
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1 hour ago, ShanRums said:
The controller is an Ipco Studio 3000, it only lets you input a target temp and not a target cone.
Yes it uses a target temperature rather than a target cone. But doesn't it also support program segments and ramp rates?
https://thermaltechnologies.com.au/wp-content/uploads/2020/06/IPCO-Studio-3000-Manual_1_.pdf
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19 hours ago, PeterH said:
I don't know if it's possible to find low-fire bodies and glazes which can be used at these temperature.
When considering this it might be worth looking at the responses to this question on another thread.
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6 minutes ago, Dana Stripe said:
Bill I would think cone 01 would be ok for low fire.
Does the plate indicate a realistic firing temperature, or the maximum that can be reached with a full-spec power supply and new elements?
I've seen a lot of recommendations that you need a cone 10 kiln to regularly fire at cone 6.
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Nothing substantial to add, but this maybe of interest.
The description "fine art" amaco kiln seems to relate to a series of kilns, can you find a more specific model number (might look like FA-<digits>). I'd hope there is a plate somewhere giving voltage, current, model number, etc. ... Can you find it and post a photograph?
PS My impression is that these may not have been intended/marketed as general-purpose pottery kilns, for example the FA-44 is described as:
http://www.americanceramics.com/html/amacofineartkilns.html
The FA-44 is a well-insulated front-loading kiln with the capability to fire to Cone 03. Practical for small classrooms and studios, the FA-44 kiln is ideal for metal enameling, china painting, and glass decorating projects. An optional base is available for storing supplies and kiln furniture.
... @Callie Beller Diesel would you use a cone sitter for any of these applications?China painting typically relates to decorating already fired and glazed porcelain, hence:
https://kilnfrog.com/collections/porcelain-china
Porcelain or China Painting Kilns are typically smaller versions of Pottery kilns. They also typically fire at lower temperatures at 2000F. A kiln intended to function for pottery and ceramics is designed to fire to higher temperatures over 2200-2350F degrees, these high temperatures are necessary for firing the clay.I don't know if it's possible to find low-fire bodies and glazes which can be used at these temperature.
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3 minutes ago, azglp said:
We are comparing the color on Cafe Beirut font and the Arabic Text. The wave color pattern is a different color
Oops, in that case Babs is right.
- Piedmont Pottery and Hulk
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17 minutes ago, Babs said:
!!Is it illusionary because of amount of white surrounding the arabic text compared to the compact Cafe Beirut design?
A very good idea. Which I tried to confirm by picking up the colours in graphics program, but they do seem different.
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Perhaps a more eye-catching title title would be "Korean-speaking potter needs help".
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Good idea Pres.
May I suggest that @scottiebie considers trying to enlist the help of those Korean speakers on the forum. Perhaps by starting a new thread (with a title something like "Korean-language beginning-throwing videos and posters needed") explaining the problem. Maybe one of the more mainstream groups such as Studio Operations and Making Work would be more likely to catch their eye.
A very superficial search suggests that English speakers might easily get overwhelmed by the number of Korean-language items on throwing Korean-style pottery (usually by experts).
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1 hour ago, Bill Kielb said:
It’s too difficult an issue for me so to candle below boiling is conservative IMO.
I'm a great believer in "If it ain't broke, don't fix it". So I'm in total agreement that keeping to your tried and true process is the smart thing to do.
To play devils-advocate. You are ensuring that there won't be problems during candling (by keeping below boiling point), and relying on your experience to know that any residual pore-water won't cause problems during the bisque. While somebody candling to 240F is ensuring that there won't be problems during the bisque (by removing virtually all the pore-water) , and relying on their experience to know that this won't cause problems during the candling. IMHO both are admirable strategies.
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4 hours ago, Min said:
How much non chemically bound water is lost during heating up to
240K240F?Most of it according to the first diagram I could find. Their ramp looks faster than yours, but I've no idea how "dry" the clay needs to be before starting this bisque firing.
https://cawstudiopotters.wordpress.com/exp/kilns-firing/
Hamer & Hamer gives:
The water of plasticity dries out from the clay in the atmosphere.
The pore water is driven off by heat up to 120C (248F).
The bound water remains as part of the clay compound (Al20O3,2SiO2,2H2O) until red heat, 600C (1112F).Elsewhere H&H say: the point at which the clay is theoretically bone dry is 120C (248F).
I'm not sure what is meant by theoretically here. Is it the same thermodynamic style of argument that says diamond spontaneously decays into carbon (which it probably does, but it takes geological timescales to do so).I've no idea where (on the above diagram) all the water of plasticity has been expelled. Nor how much might be present before candling starts.
PS Looking athttps://www.lakesidepottery.com/HTML Text/Tips/Clay drying and firing process.htm
When the water has evaporated form between the clay particles, and all the remaining clay particles are in contact, drying shrinkage is complete. This is called the leather hard stage. The particles themselves are still damp, but their drying will not cause any additional shrinkage.
So maybe the terminology is as simple as:
Wet clay has water of plasticity, pore water & chemically combined water.
Leather hard clay has only pore water & chemically combined water.
Bone dry clay has only chemically combined water.
Bisque clay has no water at all.
... which still leaves the practical matter of telling when an actual pot reaches these idealized states. -
1 minute ago, Min said:
One variable that hasn't been explored is the heating up rate of 80F/hr to the target temp of 240F that I used. What is happening to the surface of the pot during that phase? What is the relationship between the clay thickness and the warming up period? What happens when this rate is increased? How much non chemically bound water is lost during heating up to 240K? At what rate did Ian Gregory heat his freshly thrown pots?
All embarrassingly good questions, I'll only answer the last one. Stuntman, singer and potter, he was somewhat of an exhibitionist and - at least at exhibitions - fired fast. His shopping-trolley kiln took about 10 mins for bisquit or raku, and 30 mins for stoneware. My vague memory was that his little-rocket reached cone 9 even faster. [Not certain if he used temperature or cones.]
Why my clay acts like this?
in Clay and Glaze Chemistry
Posted
This sort of idea is often recommended:
https://www.clayartcenter.org/clay-art-center-blog/2020/3/how-to-rehydrate-bone-dry-clay-easily
Video of the same idea on a slightly smaller scale: