.jpeg.e14571b8528e66a7a9c872fd28550125.jpeg)
Min
-
Posts
5,890 -
Joined
-
Last visited
Content Type
Profiles
Forums
Gallery
Posts posted by Min
-
-
No clue if it’s still current but there is a post in this thread from Clayart 2002 where he gives his phone number. http://www.potters.org/subject59787.htm
-
Hi Gabriella, there is a section here on the forum where you could post the kiln you have for sale. Link here to it: https://community.ceramicartsdaily.org/forum/33-community-marketplace-–-buyselltradefree/ If Craigslist is active in your area you could try there too.
-
You can inscribe it as soon as the wax is dry to the touch. Let the underglaze dry before wiping it back.
-
New Zealand halloyiste is really white but it's expensive. Could always add some zircopax to your epk if you find it isn't white enough.
-
Clay needs to be leatherhard, I would try sooner if it hasn't been crisp lines and see what happens. When I did it I waited until the sheen was gone, You are using a smooth claybody right?
-
13 hours ago, Denice said:
so I need 50 lbs of custar
Custer is a potash spar, that means there is more potassium than sodium in the spar. Kona F-4 is a soda spar, it has more sodium than potassium.
I for sure would hold on to the Custer given the recent closure of the mine. Kona F-4 hasn't been available for a few years, its replacement is Minspar 200 which works as a 1:1 replacement for Kona F-4.
I tend to hold onto materials, never know when you will need something if trying out new recipes or if something becomes obsolete.
-
Hi and welcome to the forum!
I've used Forbes wax resist with good success for this. What you don't want is a wax resist that is oil based (these are the ones that are difficult to wash out of brushes).
-
Hi and welcome to the forum.
13 hours ago, Batuu said:I had been absolutely blown away by the use/waste of energy and materials.
For sure it takes a heck of a lot of practice while learning to work with clay, who decides when a piece merits turning it from a recyclable lump of clay into something permanent that isn't readily recyclable? Is there value in a piece of functional work that with more experience a beginning potter could make better? I would say yes. Should the beginner be encouraged to only fire their best work? That's a difficult question to answer and I don't think there is a right or wrong answer here, it depends on the situation. I would argue for a child to have something permanent, regardless of the quality, it can lead to a lifelong enjoyment of ceramics and a feeling of pride. Should an adult with less than stellar skills fire their work? In a perfect world the instructor would have the student make multiple pots and follow this with a lesson in constructive criticism then with the students okay a culling of "lesser" pots encouraged.
Are there lessons to be learned as we progress with our skills to be learned from looking back at early work? I think there are. I have made a lot of real clunkers while learning, it can take years to really see the flaws in design or workmanship.
13 hours ago, Batuu said:further material lectures being a complete rarity. Nevertheless people are motivated to produce masses of products, never having heard about things like vitrification, abrasion, hygiene, glaze mistakes, etc.
Perhaps this is a reflection of the studio environment. Are these classes set up as instructional classes with glaze theory etc or are they recreational classes? Hiring practice for the instructors set high enough?
13 hours ago, Batuu said:I am not talking about some single pieces people give to friends or keep for themselves. I am talking about a whole new movement that does not seem to be interested the slightest in learning before/while making, but putting LOTS of effort into creating Instagram reels and corporate identities surrounding slow making and sustainability.
This is a really good thought. I don't spend much time on social media but for sure when I do go there it seems there are a lot of people working the system like you describe. Like I said though, I don't spend a lot of time looking, perhaps the question could be do makers of quality pots use social media and if so how heavily do they rely on it? @Callie Beller Diesel and @GEP, thoughts on this?
-
I don't know how the price compares to Brent but I like my Bailey wheel with the removable splash pan. (bumping this thread, hope to get more replies)
-
12 000 gram batch of glaze, made up approx 21 L which would be just over 4 1/2 Imperial gallons of glaze. Recipe contains china clay (grolleg?) at 15% so it shouldn't be hard-panning. 5 tablespoons of saturated epsom salts solution added but glaze slurry still leaving heavy drip marks. Typical amount of epsom salts solution would be in the range of 1 tsp per US gallon (0.8 of an Imperial gallon)
Has the efficacy of the epsom salts solution been tested? Have you tried a new saturated solution?
Is the method of dipping the pots part of the issue? Is this a clear glaze high fire? How are the drips with a lower sg? How does the glaze look when fired with a lower sg?
-
Okay, so in a very simplified nutshell a glaze at any temperature will have 3 main components. Silica (think of this as the bones of a glaze), Alumina (think of this as the flesh of a glaze) and Flux(es) (think of this as the blood of a glaze). All glazes, regardless of cone or firing method, will be comprised of these components. Fluxes are almost always used in combination with other fluxes, ie a glaze will have more than one flux. Silica can be sourced in a glaze as silica and it's also in feldspars etc, a good source of alumina is kaolin or ball clay.
The higher the cone firing the less fluxes are needed, so by definition there will be room for more alumina and silica in higher firing glazes than lower firing ones. Sounds like your glaze is over-fluxed for the cone you are firing it too.
When you added silica to the WC554 glaze it "did the opposite" I'm guessing it went more gloss? I would hazard a guess this is because you altered the silica:alumina ratio. This can happen when you add silica to a high alumina matte formula. High alumina mattes are glazes where the ratio between the silica and alumina fall within a certain range, adding silica to it will move the glaze into the territory of a semi or gloss. (This works when there are sufficient fluxes to dissolve the extra silica)
What I would suggest doing would be to weigh out a sample amount of dry glaze, say 200 grams, then add both silica plus epk to it. The ratio of the two is important, for every 1 gram of epk you need to add 1.25 grams of silica. Start with adding 10 epk and 12.50 silica to the 200 grams base then mix/sieve and dip a test tile. Repeat adding 10 epk plus 12.50 silica twice more and repeating the test tiles. Fire those and see what happens, in theory it should help stiffen up the glaze and return it to less of a gloss. If it's still too glossy then try with just adding the epk and omit the silica. (or run this test at the same time) Between the 2 tests, one adding both silica plus epk and the other just adding epk I think there's a good chance of success.
If the colour is diluted too much by the silica/epk then address that by adding copper carbonate, have to see how the tests turn out before guesstimating how much of that to add. The purpose of these tests is to "dilute" the fluxes. Like I said this is a crapshoot as we don't have the recipe to work from but I think it's worth trying.
-
22 hours ago, Gonepotty said:
Clay is slightly grogged
Some people find it helps to dip pots in water very briefly before glazing if the body is grogged. Theory is the water expels any tiny air pockets cause by the grog so when the pot is dipped in glaze there isn’t trapped air which in turn can cause pinholes in the glaze firing. If the body is burnished with a rib after trimming this is reduced.
-
Falls Creek "Shino" and others that mimic that look are usually dangerously high in lithia. Ideally the maximum amout of lithia at the very top end shouldn't exceed 0.20 molar. Whichever iterations of that glaze you land up using I would really suggest lowering the lithia content if it's above that, whether it's supplied by spodumene, petalite or lithium carbonate. In your posted reciped dropping the lithium carb from 6.5 down to 4.5 and then really testing for shivering (expecially on low expansion bodies) would be a good idea. Before Alberta Slip became popular these type of glazes usually employed Redart (or a similar earthenware clay) to supply the iron, don't know if you have tried a sub with that? (and rebalanced)
What are the recipes you have tried that haven't worked out? Need a hand with reformulating the recipe you have?
- Rae Reich and davidh4976
-
2
-
It's going to be a real crap shoot trying to alter a glaze without the recipe. Which is the glaze that is giving problems, Laguna Turquoise ^10 WC554? Has the amount of reduction you are doing increased?
-
Hi and welcome to the forum!
Were they Mason stains for claybodies specifically? Which colour numbers?
-
4 hours ago, Dick White said:
The opposite is how to shorten it. Grasp short sections in both hands and push them together, until you have scrunched the whole length. This preserves the doubled ends and the overall resistance.
+1
This!
-
8 hours ago, Gonepotty said:
with regards to increasing the second ramp, is this likely to alter the appearance of any glazes or cause any blistering etc? I’m quite new to using my own programmes rather than using the standard presets of the skutt kiln.
As long as the final segment is slowed down (as you are doing) then no, speeding up the second segment should't cause any issues. Have a look at the "slow glaze firing profiles" from L&L kilns, regardless of final cone reached the middle ramp goes at 400F / hr. (204.4C / hr).
A heads up though, when using a set temperature as your final cutoff point rather than a cone you will need to keep an eye on your results and or cones as your elements wear. Given that the kiln will need to fire longer to reach a set temperature the extra heatwork needs to be taken into account. If you look at the Orton cone chart you can see that for cone 8 (using self supporting cones) for the last 100C of rise using 15C/hr gives a top temperature of 1211C, at 60C/hr it raises to 1249C and at 150C/hr it needs to go to 1271C. So if you program in 60C/hr but the kiln can't actually keep up with that then the final heatwork will be greater. This is not a big deal if you are keeping watch on what your cones are telling you.
One other point re your pinholes, and the possibility it is being applied too thick, are you measuring the glaze specific gravity? Is your claybody a grogged one?
-
4 hours ago, Gonepotty said:
firing schedule (Celsius) is 1) 90o per hr until 300oC. 2) 115o per hr until 1080c 3) 60o per hr until 1220oc with a 20min hold. Pin holes could have been caused by a glaze too thickly applied
Pinholes can have a number of causes, if it's an issue that you haven't been able to fix I would be looking at trying a drop and hold (soak) schedule as a first possible fix. To do a drop and hold let the kiln free fall in temp to approx 40C below top temp then hold there for 20 minutes then kiln off (if you don't do a slow cool). If the glaze is fairly stiff then yes for sure having it too thick could be the cause of the pinholes.
I also think you could try increasing your second ramp to about 175-200C per hour up to 1120C. It shouldn't have any effect on the pinholes and it will decrease your length of firing. It's the last 100C of the firing that is typically slowed down to 60C/hr.
-
Hi Lilith and welcome to the forum.
Have you measured the resistance of the element(s) to see how much they have degraded since new? Any chance you measured the resistance of all the elements before you installed them?Do you have specs on APM elements for the 1231PK when new?
-
1 hour ago, Dave Earley said:
Here are the bowls fired to electric cone 10 with a semitransparent blue glaze
Nice! Are you thinking of running some absorption, shrinkage and warping tests on it? One time experiment or do you have enough of it to use for more pots?
-
I'ld call that cone 8. Do you do any sort of drop and hold/soak on the cool down? What is your rate of climb towards the end of the firing? Are the pinholes a new issue? Glaze recipe(s)?
-
@PaulineNL, link to cone information firing temperature chart from Orton in this thread. Have a look at how cone numbers go up as the temperature goes up. As you can see there is a big difference between cone 05 and cone 5. What you are doing is like trying to bake a roast that should be baked at 350F at only 150F, it just will never be "done".
Amaco Velvet underglazes can often be fired hotter than cone 05 without too much difference in the colour. Link here to a field guide from Amaco for their Velvet Underglazes, fired with one of their clear glazes, to cones 05, 5 and 10.
There is no point firing a cone 6 glaze, like the one you have applied to this work to just cone 05, this is far too cool and why your glaze is not fully melted.
If there is no risk of the glaze running onto the shelves then fire the kiln to cone 5. If there is a risk of the glazes being to close to the bottom of the pieces then I would sit each one on a small flat pad of clay (a clay cookie) that way if the glaze runs it will stick to the cookie and not the shelf. These clay cookies need to be totally bone dry before firing the kiln and can be reused.
Going forward match the clay maturity firing temp / cone to the glaze. Not all glazes will work well over all underglazes so it's a good idea to test first on test tiles.
-
How big is the kiln and what is your schedule for turning up the dials? Are your clay and glazes okay with the fast bisque firing?
-
Cress Kiln for sale
in Equipment Use and Repair
Posted
Post some pictures of the inside, outside and faceplate. Plus if there are any kiln shelves and posts.