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Post by jack33001 on Mar 28, 2018 20:20:30 GMT -6
Hi Everyone, I'm a high school student who's been working with ceramics for a few years, and I've become interested in mixing some of my own crystalline glazes. As I am a student, I have no control over the firing schedule, so I'd like to know if the routine at my school is possible to get crystal formation from. We fire to about 2200, but do not hold it. It is a steady ramp up to that temperature over 6-8 hours, and it cools at 83 1/3 degrees Fahrenheit per hour from 2200 to 200, then we open and unload the kiln (its a gas kiln). I've heard you can get crystals in a cone 5 firing, so I feel like it gets hot enough, my main concern is that we don't hold it and the cooldown seems a little fast. If this does sound plausible, I'd appreciate any tips as well.
On an unrelated note, what mesh size should my sieve be?
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gczop
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Posts: 202
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Post by gczop on Mar 29, 2018 8:28:39 GMT -6
Hi, You may or may not get small crystals as the temperature falls through the growth range. Seeding improves chance of nucleation and growth. G.
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Post by jack33001 on Mar 30, 2018 10:47:17 GMT -6
If I were to make any changes to the firing schedule to facilitate larger growth, what would you recommend?
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Post by jfox on Mar 30, 2018 14:46:13 GMT -6
put a hold at around 1100 C on the way down one hour will start to show 5 would be better
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Post by tileman2 on Mar 30, 2018 17:40:43 GMT -6
Firing schedule aside; two other points of interest. 1. Standard yellow zinc ( sphalerite) does not like lower temps. I have grown crystals with a peak temp of 2185; however I used metallic zinc in one experiment and white zinc in the other. 2. Lithium carb was increased to four percent.
It can be done, but some changes to the basic recipe are needed.
Tom
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Post by jack33001 on Mar 31, 2018 20:00:15 GMT -6
I found a ^5 formula that I like the results of, any tips before I go ahead and buy my materials?
50% ferro frit 3110 26% zinc oxide 20% Silica 325m 3.9% Lithium Carbonate .1% Titanium Dioxide (seeding agent)
I'm also going to see if I can convince my teacher to mess with the firing schedule, I can probably get him to add 1 hold.
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gczop
Full Member
Posts: 202
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Post by gczop on Mar 31, 2018 21:10:51 GMT -6
Go for it and let us see your results, you have some interested bystanders willing to assist. We may learn something as well. G
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Post by jack33001 on Apr 6, 2018 17:42:05 GMT -6
Just headed to my local ceramics shop and picked up all my ingredients, next ^5 firing will be a week from Monday. Wish me luck!
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Post by jack33001 on Apr 17, 2018 12:52:00 GMT -6
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Post by Arnie Benton on Apr 18, 2018 9:57:35 GMT -6
Hi
You should add some bentonite or vgum T to your glaze recipe - I usually use 1 or 1.5% of vgum T. But even with this addition, the glaze has to be remixed - stirred with a spoon - every few minutes -
Good luck!
Arnie
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Post by jfox on Apr 18, 2018 13:54:18 GMT -6
I do single fire so i add 7% ball clay I also add 2% gersley Borate because i believe it improves brushing and settling problems I think it acts as a defloculant but dosnt cause the problems i get with darvan or cmc. my glaze stays suspended and dosnt form that rock hard precipitate. i take out some of the silica to balance the added clay
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Post by jack33001 on Apr 28, 2018 13:17:09 GMT -6
Alright everyone, the first batch is done! I see a few things that could use improvement (ie. the crazing and lack of shine in the middle of the crystal), but it’s a good start. Here’s the link to the new google drive uploads. drive.google.com/open?id=1--oc3MNB-mXu43PVB7pj65jUE76j5KbLSo now my to do list seems to be as follows: 1. Solve the crazing 2. Solve the shine issue within the center of the crystal 3. Begin playing with colors I'd love some input here, especially with a few cheap pigments to begin with. Also, how does one color the base glaze a certain color without coloring the crystals the same?
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gczop
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Post by gczop on May 4, 2018 8:07:14 GMT -6
This is about your note on glaze and crystal colors. Willemite crystals have a preferential uptake of some colorants; see Microscopy and microanalysis of crystalline glazes article table below. You will see from the table that for example Co in low concentration may be completely removed from the glaze (ground). Ni usually colors crystals a type of blue while ground is different. Cheers, Gordon Pot Willemite crystals Glaze Element Mean composition (at%) Element Mean composition (at%) P1 Cobalt 0.38 Cobalt 0.09 P2 Cobalt 0.10 Cobalt 0.00 P3 Copper 0.49 Copper 0.71 P4 Nickel 0.93 Nickel 0.40 P4 Iron 0.11 Iron 0.28 P5 Iron 0.36 Iron 0.69
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betty
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Post by betty on Dec 1, 2023 7:08:09 GMT -6
Wonder how it turned out? I’m in the same predicament, Community gas kiln will be ramped up to cone 10 with a natural cool. Recipe calls for a tiny amount of lithium Cone: 10 Firing: Ox. or Red. Recipe: Percent Batch Lithium Carbonate 0.18 Zinc Oxide 28.77 Ferro Frit 3110 43.59 Bentonite 2.18 Flint 25.28 Hopefully some crystals will show. I’m not sure where to find seeding agents. Any thoughts? (Canada)
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gczop
Full Member
Posts: 202
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Post by gczop on Dec 2, 2023 11:03:29 GMT -6
Hi Betty, previous post: {anything above 1200c ok}: Mar 18, 2020 at 5:59am serian said: I take 162.8g ZnO and mix it with 60.1g SiO2. These are the stoichiometric amounts for the formation of willemite. I burn this mixture during a normal crystal glaze firing. This gives me a rather hard product, which I then break up and sieve out. 0.3mm - 0.4mm pieces are ideal for seeding crystal glazes.
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