Kelly in AK

It’s helpful they’re powders. Rutile was my first thought as well, it makes a really nice off-white. Be sure to test small amounts, thoroughly, before going all in. Rutile has a nasty reputation for producing pinholes in some glazes. 

Yes, they’re neodymium, from United Nuclear, the most powerful magnets I’ve ever seen. Your warning is well placed @PeterH, I don’t have any kids around and these things still scare me. I used the word “play” loosely. Not toys. 

Ouch! Hope you get better as quickly as possible.

When 19, had a major accident that did number to my lower back(seatbelt fracture). For years would get sore in lower back when having to lift using back muscles or arms extended. Fount that wedging clay helped, or hanging from an over head bar wiggling my hips with the weight stretching the spine. Temporary relief when repeated enough helped.
 
best,
Pres

I hope your back gets better soon,  bed rest always fixed my dogs back.   All of my dogs seem to have a little dachsund in them.   I would roll them in a blanket like a sausage and put them in their bed.   I would check on them every 4 hours,  take them out, water or feed them and them roll them back up.   After a couple of day the crisis would be over, I hope yours is.   Denice

The glaze applied easily and came out beautifully. Thanks so much for everyones input it was really invaluable. I have some shino questions coming up so stay tuned!!
 

It’s really no different than adding insulation to your house. Adding double reduces losses to ~ half. R value of materials are basically additive for homes, kilns are similar. How it’s done is key so if just building a kiln no worries. If retrofitting then removing the steel shell easiest way. The lid is also an issue as over heating the already banded bricks can cause larger deflections and lid failure. Easiest improvement for the effort I have seen is Add 2” rigid to the interior of top and bottom where maximum heat loss exists anyway. But to answer your question, more insulation, less power to make cone, but also slower to cool down.

I fired the kiln on Memorial Day. Some pieces from local clay, the bisque ware has been building up, I finally had time to glaze fire. Somehow I threw my back out (couldn’t be from those thick silicon carbide shelves, could it?), so I haven’t even peeked at the result. It’s a first, I’m usually standing there with gloves on wishing the kiln would cool just a little faster. In bed all day instead. Enforced rest period, I guess. 

I fired the kiln on Memorial Day. Some pieces from local clay, the bisque ware has been building up, I finally had time to glaze fire. Somehow I threw my back out (couldn’t be from those thick silicon carbide shelves, could it?), so I haven’t even peeked at the result. It’s a first, I’m usually standing there with gloves on wishing the kiln would cool just a little faster. In bed all day instead. Enforced rest period, I guess. 

Definitely use bentonite and then flocculate it with Epsom salts, that should help the suspension issues. There’s no clay in this recipe, maybe 2% bentonite. I believe Veegum fires cleaner than bentonite and has equal or better suspension properties. 

So I had some trouble with my Porthos rubber masters of my original plaster mold.  Having used a silicone rubber with a slightly lower shore hardness I had to rejacket my rubber mold masters to prevent warping.  I should have known better than to fall for that great sale!  Hahahaha.  Once past that I could finally pour my production plaster molds and yesterday I finally slip cast another of my Porthos sculptures.  For any of you who follow my album or my previous thread on this draft horse sculpture he is normally standing with his head turned to look back behind himself.  But as I am a sculptor I also like to play with the clay!
Instead of the usual assembly of the cast parts,  I fabricated him an all new neck, tail, and then shifted two of his legs around a bit.  I'm in the process now of fixing his shoulder and haunch accordingly and added the start of a mane.  Still plenty of clean up and fine tuning to go!  Once you slip cast a piece you don't have to dry and fire it the same as it came out of your molds.  You can also rework, resculpt, reposition, redetail to produce completely new and exciting one of a kind pieces!
By the time I am done with this boy and get him onto his base he's not going to look much like my original Porthos sculpture.  I've redone him to be a heavier continental European breed or even Russian Draft.  Clay is so much fun!   Soon as I get him to the point that he's ready to dry and bisque fire I'll cast another one to see what other repositioning and resculpting antics I can get up to.  Breyerfest is only about 6 weeks away so I don't a lot of time but I might manage to get two new pieces completed.  Wish me luck!

LOL.
I've found glazes sometimes behave like children, some just don't want to play nicely. Others have issues interacting with others. Some think they are princesses and need special attention. Some will just hunker down and sulk and not move while others want to run all over the place.  Mother of 4. 

It takes very little reduction to keep a kiln in reduction during cooling. Small pieces of wood are an easy way to do it in a kiln that's already got bricks that are glazed up from soda or salt, but I wouldn't do it in a straight gas kiln because it'll make a mess of the fireboxes at cone 10. The other option is to seal off the burner ports and just have a small pilot burner going though a small hole.
If you want the clay to be black from reduction cooling, use a clay body that has 4.5% iron in it. Letting in small amount so oxygen at various points in the cooling will cause flashing.

Definitely use bentonite and then flocculate it with Epsom salts, that should help the suspension issues. There’s no clay in this recipe, maybe 2% bentonite. I believe Veegum fires cleaner than bentonite and has equal or better suspension properties. 

Hi Suzana, 
I missed this post way back in March but just stumbled across it today. In case you’re still playing with reduction cooling, I’ve been doing it a couple years now at cone 6 in a soda kiln. When I first tried it I noticed better flashing, more contrast, and fewer pots that were plain gray blending into boring tan. After a few more tries, I’m completely sold on it. It’s normally talked about in conjunction with iron rich clay, but I use white stoneware (B-mix 5) and buff stoneware (various bodies), and a flashing slip made from Helmer kaolin. The buff clays become much more orange than they would be in an electric kiln. 
 I use a fairly standard reduction schedule, start around 012 for around an hour, then light reduction to cone 6. I spray in soda when the cones are down and reduce it pretty heavily. I’m also throwing wood in while charging with soda. I charge it, let it recover, then repeat until the soda’s all in the kiln. I get it back to temperature, then shut it off.
The reduction cooling just consists of putting wood in the clammed up kiln periodically until it’s between 1450°-1650° or when I’m just too wiped out to care. I try to keep it always smoking, some smoke out of the bottom spy hole. It adds a couple hours to the firing. It’s probably not the easiest way to do it, but I know it works so I keep doing it.

Try emailing it to yourself and then try posting that image.
Rutile changes can definitely cause pinholes/blisters, would be one of the first things I would test for. If you have some titanium dioxide I would suggest mixing up a couple hundred grams of both bases and sub titanium dioxide for the rutile. Glazes will be missing some of the trace elements found in rutile (that are missing from titanium dioxide) but it likely won't make a significant difference to either glaze. For the Waterfall Brown use 0.90% TiO2 in place of the 1.00% rutile and in Spearmint use 5.35% TiO2 in place of the 6 rutile. (I took the rutile amounts from the recipes as published on Glazy)
It's usually best to just change one variable at a time.
edit: you verify your glaze firings with cones, correct?

Scarva, from what I see, doesn’t publish absorption numbers for this clay body. It’s a worthwhile test to do yourself. I believe you’re firing this clay at its upper limit. As @Min said, gas that’s trapped will form a bloat. It may well be from the clay sealing itself as much as the glaze sealing gasses in. It’s noteworthy your photos show single large bloats/blebs, rather than several evenly distributed ones. 

I love your monkey! The tail needs to go from thick to thin and be half as long. Long and skinny would be nice, but you’re asking far too much from the clay, if I’m understanding correctly. Especially if it’s expected to carry a load of bananas. 

What I’ve noticed about flocculation in general is that either bentonite or epsom salts alone work a little, but the 2 together work better.  Personally I’d rather have enough clay in the recipe and use the epsom for suspension. I dislike using bentonite because dispersing it properly is a nuisance. I don’t find the drying time from Epsom to be a problem with my workflow, but that’s a personal preference.
If the 4 % bentonite works for you, there’s no need to fix it. It’s just a different solution to the problem of how to keep non-gerstley glazes suspended .
 

I think you're right about the bentonite, it was one of those things where right after I added it I thought, "hmm, probably not going to help with what I'm trying to do." Then plowed right ahead anyway. Don't think I'll use it in the next batch.

I can’t add more to this excellent discussion in technical terms, but offer some general principles that could be “useful ways to think” about your materials. Ball clay shrinks a lot. It’s great for keeping things in suspension while also giving you the alumina and silica the glaze needs. It has good green strength, so helps dry glaze be less powdery. Kaolin is the star for alumina and provides plenty of silica, among its other good qualities. It has lower green strength, but shrinks less, and will still aid in suspension. It’s more expensive, but that’s truly a drop in the bucket compared to your time. The reason bentonite is used in a glaze is to help with suspension, that doesn’t seem like a problem here. Both the ball clay and the bentonite hold on to water and will make the glaze dry slower. CMC may, by its sheer “gluey” force, may keep the glaze from peeling apart, but it will add to the time it takes your glaze to dry. 
My instinct when you said you added bentonite (to a glaze with 20% ball clay) was that it would make the problem worse because it’s only adding to the shrinkage issue. That’s my sense of the root of your problem. I think kaolin in general is a good direction. Calcined kaolin is the off-the-shelf workhorse for reducing wet to dry shrinkage. 
 

I can’t add more to this excellent discussion in technical terms, but offer some general principles that could be “useful ways to think” about your materials. Ball clay shrinks a lot. It’s great for keeping things in suspension while also giving you the alumina and silica the glaze needs. It has good green strength, so helps dry glaze be less powdery. Kaolin is the star for alumina and provides plenty of silica, among its other good qualities. It has lower green strength, but shrinks less, and will still aid in suspension. It’s more expensive, but that’s truly a drop in the bucket compared to your time. The reason bentonite is used in a glaze is to help with suspension, that doesn’t seem like a problem here. Both the ball clay and the bentonite hold on to water and will make the glaze dry slower. CMC may, by its sheer “gluey” force, may keep the glaze from peeling apart, but it will add to the time it takes your glaze to dry. 
My instinct when you said you added bentonite (to a glaze with 20% ball clay) was that it would make the problem worse because it’s only adding to the shrinkage issue. That’s my sense of the root of your problem. I think kaolin in general is a good direction. Calcined kaolin is the off-the-shelf workhorse for reducing wet to dry shrinkage. 
 

2% bentonite ought to be enough, but I’m not arguing with John Britt. Perhaps a more plastic form of kaolin? EPK is popular. (Edit-I was reading at unsafe speed and didn’t notice you were already using EPK).
Epsom salts, try it before going to great lengths to avoid it. I’ve spent too many precious minutes of my life scraping the sludge off the bottom of a bucket and get it in suspension. I never have that problem anymore. I sincerely mean never. I don’t know the dangers of using Epsom salts over increasing bentonite, I do know that I can adjust the viscosity of the glaze at will by flocculation and it works like a charm with every glaze I have. 
I use a glaze with 10% kaolin and 2% bentonite as the only plastic ingredients, frit and silica make up the balance. Epsom salts keeps it in suspension, doesn’t hardpan after months of sitting in the bucket. Another one I use is Selsor red, no clay in that one at all. The Gerstley borate helps with suspension, but if you leave out the bentonite (2%) it will hardpan in a day. Without Epsom salts it’ll still settle quickly. With Epsom salts it doesn’t hardpan over months. 
(Edit- I see you were offering an observation, not seeking a solution. It’s much appreciated. I’m down to fifteen pounds of Gerstley borate and I’ve got a couple glazes to reformulate myself. Been putting that off.)

I can’t add more to this excellent discussion in technical terms, but offer some general principles that could be “useful ways to think” about your materials. Ball clay shrinks a lot. It’s great for keeping things in suspension while also giving you the alumina and silica the glaze needs. It has good green strength, so helps dry glaze be less powdery. Kaolin is the star for alumina and provides plenty of silica, among its other good qualities. It has lower green strength, but shrinks less, and will still aid in suspension. It’s more expensive, but that’s truly a drop in the bucket compared to your time. The reason bentonite is used in a glaze is to help with suspension, that doesn’t seem like a problem here. Both the ball clay and the bentonite hold on to water and will make the glaze dry slower. CMC may, by its sheer “gluey” force, may keep the glaze from peeling apart, but it will add to the time it takes your glaze to dry. 
My instinct when you said you added bentonite (to a glaze with 20% ball clay) was that it would make the problem worse because it’s only adding to the shrinkage issue. That’s my sense of the root of your problem. I think kaolin in general is a good direction. Calcined kaolin is the off-the-shelf workhorse for reducing wet to dry shrinkage. 
 

Here's the little tray. I chickend out & didn't do much w/the manganese-I did wipe on then off, but very lightly & used it for the outlining. I'm happy-he's cute!