Callie Beller Diesel

The digital fire link seems a pretty good example of the difference a smaller mesh can make.
 
The smaller the better in my opinion for melting silica. I remember back to my bubble experiments and removing quartz/silica additions and trying to source from feldspars/clays always had a better melt. Glazenerd did send me some super fine silica that is still on my list to test about 7 years later 

@tyler it could be a good idea to check with your local clay supplier if anyone who can do that for you. Every clay person I know likes to talk about what they like (clay) to anyone who will hold still long enough to listen to them. They’ll know someone who knows someone. 

Mostly throwing large amounts of items on a slow wheel with soft clay is an exercise in economy of motion. In the absence of knowing exactly what you’re doing/not doing, it’s hard to troubleshoot exactly. A good resource to check out might be YouTube though, because sometimes a video can reveal a lot in a short amount of time. If you find it difficult to watch a video tutorial, something that can help is adjusting the playback speed. But if you need text versions, I’ll tag @PeterH, as he’s got a gift for tracking down all kinds of good articles. 
I’m curious as to why you’d want to use a kick wheel if you’re going in to production pottery though. Kick wheels tend to be harder on the body than electric ones, and that’s an important consideration when you’re looking at a job that can have a high propensity for repetitive motion injuries.
Production pottery of any kind is about economy of motion and making things efficiently, so that you can make a lot. Any choice made about how you work that isn’t about efficiency has to have a compelling reason to be included in your process.  If you’re using a particular technique that takes more time, you have to find ways of offsetting that elsewhere in the process. Or the results have to be able to provide enough value in the finished work to be worth the effort. 
 

If you’re making functional ware, spray paint isn’t going to be a good route. Sculptural stuff? Cold finishes all the way. It opens up sooooo many cool possibilities.

It’s not for food. Liquitex matte medium, a room temperature finish, may fit the bill. It’s UV protectant. Produces a satin finish. Reliable and long lasting. Your fired pieces should be archival without that though.
 

50 years ago, the standard was also cone 10 reduction, and I think cone 6 was filed under “interesting but impractical.” So the extra heat work took care of the difference that the silica mesh size would have made. 200 mesh sil-co-sil was all I could get back in the 90’s, so I used it. And I was firing at cone 10 at the time, and it was fine. 
When I made the switch to cone 6, I came across much of the same info you’ve already listed, and the 350 mesh was more available. I was less concerned with crazing at the time, but I can say that the mesh size makes a difference in glaze clarity at cone 6. 
 
 

Mostly throwing large amounts of items on a slow wheel with soft clay is an exercise in economy of motion. In the absence of knowing exactly what you’re doing/not doing, it’s hard to troubleshoot exactly. A good resource to check out might be YouTube though, because sometimes a video can reveal a lot in a short amount of time. If you find it difficult to watch a video tutorial, something that can help is adjusting the playback speed. But if you need text versions, I’ll tag @PeterH, as he’s got a gift for tracking down all kinds of good articles. 
I’m curious as to why you’d want to use a kick wheel if you’re going in to production pottery though. Kick wheels tend to be harder on the body than electric ones, and that’s an important consideration when you’re looking at a job that can have a high propensity for repetitive motion injuries.
Production pottery of any kind is about economy of motion and making things efficiently, so that you can make a lot. Any choice made about how you work that isn’t about efficiency has to have a compelling reason to be included in your process.  If you’re using a particular technique that takes more time, you have to find ways of offsetting that elsewhere in the process. Or the results have to be able to provide enough value in the finished work to be worth the effort. 
 

Oh gosh, sorry, don't know how I missed that. Okay, so plan B would be to make up a slip and use some oxides to make a black. Slip needs to go on greenware, as soft leatherhard as possible to avoid fit issues. Also test the covering glaze over it before committing a "real" pot. There are recipes for black slips that contain various amount of colouring oxides, most include iron + manganese + cobalt and sometimes chrome also. Something along the lines of this recipe from Vince Pitelka. 

if you are thinking of firing that paint, it won't work.   if you finish firing to the final temp and have left some areas free of glaze so you can add some zing that would work.   a potter who did that was featured on the cover of ceramics monthly years ago and caused quite a stir.   i may remember his name later.

The answer is #3
#5. The kiln will stink more than usual as well
# 6 try it and learn .
School of hard knocks has the best lessons

Usually I work things pretty close together, so I don’t need a lot of “long term” (more than a week) storage these days.  Mostly I use a double layer of plastic to cover things, but I did get a large under-bed plastic tote for handles that I use in a similar manner to what you describe @Pres. I have to ask though: why the board or plate over the sponge? I’m picturing a small throwing sponge or similar, as that’s what I use. 

I found a reference on the Laguna website that said they acquired the Westwood Ceramic Supply company. I’d suggest reaching out to them. I didn’t find any glazes in their current catalog with a WR number, but they may have older records.

We had a situation about a year ago where we started to get crazing on glazes that had never crazed before. It took a lot of trial and error testing with known good batches of materials to determine the problem. It turns out that we had received a batch of 200 mesh silica by mistake instead of 325 mesh. Because there was no clear "mesh" marking on the bag, no one realized that we had received 200. The glaze mixers had unknowingly started using 200 instead of 325 in the glaze mixes. Switching back to 325 solved the problem.  Of note, the crazing happened only on cone 6. We did not get crazing on cone 10. My theory is that cone 6 was not hot enough to melt the 200 mesh completely, but cone 10 was able to completely melt all of the 200 mesh.

@davidh4976, good job on subbing the Custer out. I like how much silica and alumina are in the formula, will make for a good durable glaze. I could see a bit of iron in the recipe if you ever wanted to tone down the blue a little.

Your new teapot is unlikely to cause you any harm, short of breaking it and cutting yourself on a shard accidentally. It doesn’t have any warnings about lead or cadmium, nor do I see any colours or textures in that line of work that would lead me to suspect any use of those materials. If you’re super nervous about anything and want some reassurance, you can get lead test kits for pottery on the ‘zon, but I’d be surprised if this item came back positive.
In the product description from your link, where it says Material Icon, there’s a number of little care instruction and definition buttons. When you click on “Iron in Powder” (likely a translation vagary) it points out that there may be some dark specks that appear in the final piece from iron impurities in the clay. There’s going to be considerably less iron that could possibly come out of this teapot than, say, a cast iron frying pan.
Glaze doesn’t work the way you’re describing, no. Whoever gave you that description may have been thinking of earthenware that was painted with some kind of lead bearing decorative slip or underglaze, but even that has some dubious underlying assumptions. 
First, not all pottery is made in the same way. Without getting overly technical, different kinds of clay that people use in different parts of the world will have different levels of porosity, firing temperatures, and a bunch of other stuff. So items made in Japan won’t use the same techniques or materials that get used in, Mexico, or the US, or even Canada. And studio pottery will not be made with the same materials/techniques as industrially produced items.  But in general, glaze is used on a clay body to make it stronger, and to make it more waterproof and easier to clean than just the clay surface would be alone. Also, it makes it pretty!
****IF**** a piece of pottery were to contain lead or cadmium, it won’t be in the clay body. Those metals will typically be present either in an underglaze decoration (they make pretty reds, yellows, oranges and some greens), in some forms of china paint decoration, or in the glaze itself. It’s important to note that a lead free clear over a lead or cadmium bearing underglaze **might** not block all lead bleed through should those materials be present. It’s also important to remember that not all yellow/red/orange/green underglazes or glazes will have any of those things in them. There’s lots of ways to get those colours that don’t involve those metals, and are safe for daily use. 
 
 

It looks like it’s a mineral of some kind (likely iron) bleeding through the glaze from the clay body. It’s quite common in stoneware clay of any kind. Nothing out of the ordinary at all.

I’ve always lived in hard water areas (my city’s website lists PPM in the 180’s for most of the year), and my fingers have likewise always wrinkled with  extended exposure to water. 

I’ve always lived in hard water areas (my city’s website lists PPM in the 180’s for most of the year), and my fingers have likewise always wrinkled with  extended exposure to water. 

Your new teapot is unlikely to cause you any harm, short of breaking it and cutting yourself on a shard accidentally. It doesn’t have any warnings about lead or cadmium, nor do I see any colours or textures in that line of work that would lead me to suspect any use of those materials. If you’re super nervous about anything and want some reassurance, you can get lead test kits for pottery on the ‘zon, but I’d be surprised if this item came back positive.
In the product description from your link, where it says Material Icon, there’s a number of little care instruction and definition buttons. When you click on “Iron in Powder” (likely a translation vagary) it points out that there may be some dark specks that appear in the final piece from iron impurities in the clay. There’s going to be considerably less iron that could possibly come out of this teapot than, say, a cast iron frying pan.
Glaze doesn’t work the way you’re describing, no. Whoever gave you that description may have been thinking of earthenware that was painted with some kind of lead bearing decorative slip or underglaze, but even that has some dubious underlying assumptions. 
First, not all pottery is made in the same way. Without getting overly technical, different kinds of clay that people use in different parts of the world will have different levels of porosity, firing temperatures, and a bunch of other stuff. So items made in Japan won’t use the same techniques or materials that get used in, Mexico, or the US, or even Canada. And studio pottery will not be made with the same materials/techniques as industrially produced items.  But in general, glaze is used on a clay body to make it stronger, and to make it more waterproof and easier to clean than just the clay surface would be alone. Also, it makes it pretty!
****IF**** a piece of pottery were to contain lead or cadmium, it won’t be in the clay body. Those metals will typically be present either in an underglaze decoration (they make pretty reds, yellows, oranges and some greens), in some forms of china paint decoration, or in the glaze itself. It’s important to note that a lead free clear over a lead or cadmium bearing underglaze **might** not block all lead bleed through should those materials be present. It’s also important to remember that not all yellow/red/orange/green underglazes or glazes will have any of those things in them. There’s lots of ways to get those colours that don’t involve those metals, and are safe for daily use. 
 
 

Your new teapot is unlikely to cause you any harm, short of breaking it and cutting yourself on a shard accidentally. It doesn’t have any warnings about lead or cadmium, nor do I see any colours or textures in that line of work that would lead me to suspect any use of those materials. If you’re super nervous about anything and want some reassurance, you can get lead test kits for pottery on the ‘zon, but I’d be surprised if this item came back positive.
In the product description from your link, where it says Material Icon, there’s a number of little care instruction and definition buttons. When you click on “Iron in Powder” (likely a translation vagary) it points out that there may be some dark specks that appear in the final piece from iron impurities in the clay. There’s going to be considerably less iron that could possibly come out of this teapot than, say, a cast iron frying pan.
Glaze doesn’t work the way you’re describing, no. Whoever gave you that description may have been thinking of earthenware that was painted with some kind of lead bearing decorative slip or underglaze, but even that has some dubious underlying assumptions. 
First, not all pottery is made in the same way. Without getting overly technical, different kinds of clay that people use in different parts of the world will have different levels of porosity, firing temperatures, and a bunch of other stuff. So items made in Japan won’t use the same techniques or materials that get used in, Mexico, or the US, or even Canada. And studio pottery will not be made with the same materials/techniques as industrially produced items.  But in general, glaze is used on a clay body to make it stronger, and to make it more waterproof and easier to clean than just the clay surface would be alone. Also, it makes it pretty!
****IF**** a piece of pottery were to contain lead or cadmium, it won’t be in the clay body. Those metals will typically be present either in an underglaze decoration (they make pretty reds, yellows, oranges and some greens), in some forms of china paint decoration, or in the glaze itself. It’s important to note that a lead free clear over a lead or cadmium bearing underglaze **might** not block all lead bleed through should those materials be present. It’s also important to remember that not all yellow/red/orange/green underglazes or glazes will have any of those things in them. There’s lots of ways to get those colours that don’t involve those metals, and are safe for daily use. 
 
 

I’ve always lived in hard water areas (my city’s website lists PPM in the 180’s for most of the year), and my fingers have likewise always wrinkled with  extended exposure to water. 

It looks like it’s a mineral of some kind (likely iron) bleeding through the glaze from the clay body. It’s quite common in stoneware clay of any kind. Nothing out of the ordinary at all.

It looks like it’s a mineral of some kind (likely iron) bleeding through the glaze from the clay body. It’s quite common in stoneware clay of any kind. Nothing out of the ordinary at all.

The studio I work at does something similar, and we wind up using hair dryers to set up the surface of the piece enough to take a coat of underglaze that isn’t streaky.

The studio I work at does something similar, and we wind up using hair dryers to set up the surface of the piece enough to take a coat of underglaze that isn’t streaky.