Potters & Sculptors - Making Rock from Mud
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I have tested Floating blue on porcelain and stoneware. Hideous murky green on stoneware. Beautiful deep blue on porcelain. Perfect on some pots, but with small sharp holes on others. Does anyone have a clue about these?
Thanks Donna, I understand about the floating blue and I am not making any so that will not be an issue. I have never had the luxury of reduction but I do dream about it! Someday when I win the lottery...I will keep you posted. N
The only glaze I have had problems with on a slow cool is floating blue. It can turn a snotty green color (has rutile, cobalt and RIO as the colorants - I assume the rutile crystals are making the green). Some people like it, I do not. The high calcium glazes will be more matt like (satin rather than glossy clear) but that is what they are supposed to do. Have you looked at the masteringglazes.com FAQ page? I am guessing so since you mention them. If I were doing reduction firings I would expect less but darn it, this should be less magic and more controllable in oxidation. It seems we should be getting some benefit from the loss of the magic of reduction (which I miss a great deal). Ok, that was my complaint for the day. Do look forward to your next tests.
I also like spodumene glazes (but miss the old grey spodumene). The one I offered does not have the problem questioned in Annie's Tan (same basic glaze minus the rutile) and it may be because of the high amount of RIO. It stands up well over time. As I mentioned in the glaze recipe the synthetic RIO is another critical ingredient for me. I agree that the test kiln was probably not adequate for an actual test since this glaze is so dependent on that soak and slow cool. Would love to hear if you get this worked out. Always nice to have more information on what is working with a Saturated RIO glaze.
The link that you provided was to an analysis of Annie's Tan. Johns comments concerned the very low alumina level. From what I have learned if you don't have at least .25 alumina (unity value) then it will not withstand repeated dishwasher use. I will try adding bone ash and switching the feldspar and then we shall see. I really have great respect for John Post and John Hesselberth. I fired to John Post's recommendation but I suspect that the test kiln was part of the problem, it is a 110/20 amp and therefore I cannot connect it to my controller. Also it is not vented so I vent via peep hole and that is not nearly as good. I remember that after I added the kiln vent it made a huge difference in color development. The additional reading that I have done is that these iron reds are finicky re a soak at cone 6, some say not to others say one hour plus the slow cool! When it works I love the bricky red that the iron reds make. On another topic I love what Spodumene does in glaze, seems to make a much nicer glass.
My bad. Your Randy's is completely different from any I have ever come across. I tried several different Saturated RIO glaze recipes that work for other people and did not work for the studio I was in when we were having problems with the glaze. Included in that was John Post's glaze which he put a lot of testing work in. The one posted worked for us. You can switch the feldspar as well and see how that works for you if you decide to try it. This glaze is mentioned on John Hesselberth's site. The bone ash is going to make it slightly less opaque making it break a bit more but I was happy with it. Testing in the big kiln may also make a difference because of the heat work. I love this glaze when it works. Hate it when it doesn't. JH's comment http://www.frogpondpottery.com/glazestability/glaze0015.html
Thanks Donna!
Here is what gave my poor results:
Silica 30
EPK 5
Feldspar G200 20
Talc 15
Spodumene 12
Frit 3134 18
Additive:
Bentonite 2
RIO 15.
The unity values were good with silica at 3.995 and alumina at .290
I don't know much about the Talc, got it from Bennett's here in Florida. I will find out what I can. I will add the bone ash and when I have the courage to try it again will re-test in my big kiln.
Gerstley 33.5
Flint 30
F4 Feldspar 20
Talc 14
EPK 5
RIO Special 15.15
Bone Ash 2.5
Synthetic or Special RIO - Spanish RIO will not work
Low cost flat lapping disc can be used on you potters wheel if you, drill bat pin holes in it, and provide a trickle of water to cool it. At amazon.com, 120 grit for aggressive material removal. Click the image to purchase
Members have had great things to say about John Britt's new book, Mid-Range Glazes. Click the image to buy from Amazon.com
Purchase Glazes Cone 6 by Michael Bailey, The Potters Book of Glaze Recipes by Emmanuel Cooper, or Making Marks by Robin Hopper, all available at amazon.com. Mastering Cone 6 Glazes by John Hesselberth & Ron Roy is now out of print.
Harbor Freight is a great place to find unbeatable prices for better HVLP spray guns with stainless steel parts and serviceable economy models, as well as detail guns, all tested by our members for spraying glazes, as well as compressors to power the guns. As yet no one has tested and commented on the remarkably inexpensive air brushes at harbor freight.
The critter siphon gun is a spray alternative that is well liked by some of our members, and is available at amazon.
Amazon is also a competitive source for photo light tents for shooting professional quality pictures of your work. They also have the EZ Cube brand favored by several of our members. You might also want to purchase the book Photographing Arts, Crafts and Collectibles . . .
If you are up to creating videos of your work or techniques you might want to invest in a flip video camera
Following are a few scales useful for potters. Ohaus Triple Pro Mechanical Triple Beam Balance, 2610g x 0.1g, with Tare $169.00
And finally a low cost clone of the OHaus. The Adam Equipment TBB2610T Triple Beam Mechanical Balance With Tare Beam $99.62
ebay is a great alternative for many tools and the equipment used in the ceramics studio - kilns, wheels, extruders, slab rollers are often listed there both new and used.
If you just want to spout off, it is best accomplished as a blog posting. If you want to get more guidance and ideas from other members, ask a question as a new discussion topic. In the upper right corner of the lists for both types of posting, you will find an "+Add " button. Clicking it will open an editor where you create your posting. 4/16/2014
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