I will send practical posts like these (from thousands I have made). No ads or tracking. One-click unsubscribe. Answer to correspond with me. If you are already subscribed the email will confirm it.
Some terra cotta clays can be used to produce stoneware by firing them a few cones higher. Terra Cottas are almost always nowhere near vitrified at their traditional cone 04-06 temperatures, so they can often stand much higher firing. However, clear glazes do not usually work well in higher firing since products of decomposition from the vitrifying body fill them will micro bubbles, clouding the surface. In addition, the body turns dark brown under clear glazes. But with a white glaze, these are not a problem. This is Plainsman L210 fired to cone 2. The glaze is 80% Frit 3195, 20% kaolin来不及说我爱你,河北彩铃网站,我的世界木鱼 and 10-12% zircopax, it fires to a brilliant flawless surface.
成年网站未满十八禁免费软件.跪在桌子下用嘴伺候主人.国产熟妇露脸在线视频456Thursday 22nd April 2021
This is important to understand that when looking at our firing schedule charts. “Degrees Fahrenheit” is a measure of the temperature of something. For example, 212F is the boiling point of water (the equivalent of 100C). "Fahrenheit degrees" are the divisions on the thermometer, there are 170 of them between the freezing and boiling point of water, for example (32-212, while there are 100 celcius degrees for the same span). "Fahrenheit degrees" are thus measures of change-in-temperature, not what the temperature is. In firing schedules, that is what we are talking about, how many degrees should the kiln rise during each step.
Context: Firing Schedule
Wednesday 21st April 2021
Quartz particles have a high melting point, they must enter the glaze melt by being dissolved by it (usually the last particles to do so). Obviously the silica should be as fine as possible to increase its surface area成年网站未满十八禁免费软件.跪在桌子下用嘴伺候主人.国产熟妇露脸在线视频456 to be more readily dissolved. The more that dissolves the closer the physical properties of the fired glaze will be its theoretical (e.g. degree of melting, thermal expansion, transparency, durability). This brand of silica, #90 (likely 45 microns) classifies as 200 mesh even though 2.8% remains on the 200 mesh screen. Not surprisingly, their #45 grade retains 1.9% on the 325 mesh screen. However, the most significant aspect is how much of the #90 is on the 325 and 270 mesh screens: 26%. The #45 grade only has 2.6! This is a huge difference and shows the value of using the finer material. It would take a typical ball mill hours to make this difference.
Thursday 1st April 2021
Can't get frit 3134 in early 2021? You are not alone. Don't listen to people who say you can just replace frit 3134 with 3124 in glaze recipes. That is wrong. Frit 3124 has five times the amount of Al2O3 (the second most important oxide in glazes) and half the amount of boron (the main melter). The glaze chemistry approach is much better, and easier than you think. To be able to do it you need two other Ferro frits, 3110 (or Fusion F-75) and 3195 (Fusion F-2). As it turns out, Frit 3195来不及说我爱你,河北彩铃网站,我的世界木鱼 is more important than is 3124! A key goal in the way I do this was to end up with at least 15% kaolin (to suspend the slurry). I have chosen three types of recipes to demonstrate. Dealing with each requires a unique approach. Two of the calculations produce improved slurry properties and one a recipe of significantly lower cost. I made a video demonstrating substituting Frit 3134, see the link below. If you have a recipe that needs this, get an insight-live.com account, enter it there and I can help you do the calculation.
Context: Ferro Frit 3134, Ferro Frit 3195, Ferro Frit 3124, 来不及说我爱你,河北彩铃网站,我的世界木鱼Is Ferro Frit 3124 a viable substitute for Frit 3134, Do you know the purpose of these common Ferro frits?, Substitute Ferro Frit 3134 For Another Frit
Monday 29th March 2021
This company was plagued with drying cracks in their solid porcelain pieces. After some time they discovered that the deaired plastic material received from their suppliers had laminations (revealed in a cross section cut of the slug). Since they were not wedging, but simply inserting the clay into their hand extruders and presses, these laminations produced built-in weaknesses, the stresses of drying later exploited these. The obvious fix seemed to be to buy a vacuum pugmill to remix the clay. But that did not work. Why? Commercial pugmills commonly have multiple shafts, hundreds of blades, large powerful motors, separate mixing and vacuum chambers, shredders, high-compression heads, etc. Small studio pugmills have none of these features. They are still great for recycling and mixing clay that will later be wedged. But for the machine-forming purposes of this company, this pugmill actually made the laminations worse!
Tuesday 23rd March 2021
Before jumping to conclusions consider all the factors that relate. Such bodies contain only about 0.2% of 60-80 mesh manganese granular compared to many glazes that contain 5% powdered manganese (as a colorant). The vast majority of the metal particles are encapsulated within the clay matrix. The tiny percentage exposed at the body surface are under the glaze. What bleeds up through the glaze, to either near or at the surface, is not the particle itself. Rather, the particles dissolve partially and bleed out in all directions. The glaze stains in relation to the MnO concentration and its own melt fluidity. The transparency and thickness of the glaze either amplify or subdue the appearance of the specks. Thus, a food surface stained by manganese is not at all the same thing as raw melted manganese in contact with food. Consider also that total area of manganese-stained glass on a functional surface is extremely small. Notwithstanding all of this, there is a public perception of glaze toxicity that must be considered, some potters thus use engobes under the glaze on food surfaces, these limit the ability of the metal particles to diffuse.
Tuesday 23rd March 2021来不及说我爱你,河北彩铃网站,我的世界木鱼
G2934Y is a fabulous base glaze but it is not without issues. It has significant clay content in the recipe and high levels of Al2O3 in the chemistry, these make it susceptible to crawling. While it is normally fine as is, when you add certain stains to color it (especially at significant percentages) or 来不及说我爱你,河北彩铃网站,我的世界木鱼opacify it using zircon (this has 10%), it can become more susceptible to crawling. On this mug, the glaze layer thickens at the recess of the handle join, that produces crawling during firing. Crawling can also happen on the insides of mugs, where wall and foot meet at a sharp angle. This happens, both because the glaze cracked here during drying and because the zircon stiffens the melt, making it less mobile. Rounding such contours will help. Even better, adjust the glaze recipe so it shrinks a little less on drying (by trading 5% of the raw kaolin for calcined). Adding a little CMC gum (e.g. 0.1-0.2%) will make it adhere better.
Saturday 20th March 2021
Why are these happening (on this piece by Paul Briggs)? It is not completely clear. The glaze has plenty of carbonates, including copper, enough for over 20% LOI来不及说我爱你,河北彩铃网站,我的世界木鱼. But these normally produce high populations of small blisters, this is the opposite. The melt appears to have enough surface tension that the bubbles survive and endure top-temperature-soaking. And they don't pop until the temperature has dropped so far that insufficient melt-mobility remains to heal them. The glaze has an unconventionally low SiO2 content, that makes it flow vigorously, well enough that the melt is moving and collecting in surface contours. The glaze recipe is quite unconventional, any effort to "improve" its adherence to limits would likely lose the visual aesthetic. A drop-and-hold firing schedule is likely the key to alleviating this.
Friday 19th March 2021
Simulating a white-on-black oil-spot effect at cone 6 oxidation proved to be a matter of repeated testing (that got me past some misconceptions). Stopping to think about the results at each step and keeping a good audit trail with pictures, in my account at insight-live.com, really helped. I had three black glazes: G2934BL satin (G2934 with black stain), G2926BB super-gloss (G2926B with black stain) and G3914A Alberta Slip black. Going on a hunch, I mixed up a bucket of the G3914A first (with some gum to help it survive second-coating without lifting). Rather than just try any white, I created 成年网站未满十八禁免费软件.跪在桌子下用嘴伺候主人.国产熟妇露脸在线视频456G3912A by substituting as much CaO and MgO as possible for SrO in the G2934Y base. I later learned this to be an error, SrO reduces the surface tension, I should have used MgO (the G2934Y is a high-MgO glaze so it would have been fine as-is)! As you can see on the far right, this white still worked (at cone 5, 6, 7, 8). Why? There is another factor even more important. The effect only works on the Alberta Slip black. But its LOI is not higher than the others. And it worked even after ball milling. So I need to continue to work on this to learn more about why this works.
Friday 19th March 2021成年网站未满十八禁免费软件.跪在桌子下用嘴伺候主人.国产熟妇露脸在线视频456
No. Because you will face a whole array of problems. This is the first, poor mold release, or more correct, impossible mold release! Plates will be too thin walled. If you cast them longer wall thickness will be uneven. Edges will crack like this (because of poor plasticity). They will warp during drying. They will lack dry strength for handling. They will warp during firing. You won't be able to get a good rim. You won't be able to cast a foot ring without an indent showing on the inside. Note here that another issue is at play: The clay is either not plastic enough to cut cleanly at the rim, without tearing. Or, it is being cut too late or with a dull knife. These tears provide places for cracks to initiate. Plates are much better made using the jiggering, ram pressing or dust pressing processes. Or by throwing them on plaster batts.
Tuesday 16th March 2021
Use the contact form at the bottom on almost all the pages on this site.
Subscribe to Insight-Live.com. It is about doing testing and development, not letting the information slip away. Starts at $15 for 6 months.
Login to your online account
Chemistry plus physics. The on-line successor to desktop Insight. Get an account for as little as $15. It does so much more.
Maintain your recipes, test results, firing schedules, pictures, materials, projects, etc. Organizing that data and learning from it will empower you. You will formulate and fix your own recipes and processes. Because it is on-line you can access your data from any connected device. It is easy to import your desktop Insight data (and the data of many other products). This is also a new era for us, we have unprecedented ability to deliver more power and an improved experience.
Teaching ceramics? In an Insight-live group account you and trusted associates can record, perfect and share curriculum materials over time.
Still using desktop Insight? Convert to the new system. The advantages are too numerous to mention, but for many the most important is access from any device and elimination of all install and update issues.
Group accounts for industry and education. Private accounts for potters. This is the future! Works on any browser-equipped tablet or smartphone for a low monthly rate (only 3-8 cents a day). Get started.
Download for Mac, PC, Linux
Interactive glaze chemistry calculations. Free and unrestricted (legacy, no longer in development).
Teaching ceramics? Use this as the least-hassle way to teach glaze chemistry. Students can later upgrade to our state-of-the-art Insight-live.com online system. You can download this here or in the Files panel within your Insight-live.com account.