Russ

One thing you can do to increase your success. Put your dry dry pieces in an oven at then turn it on to 200f for an hour. Then slowly bump the temp up to 250 for a bit and then let cool. This will remove the physical water and give it a better chance to make it thru a pit firing. Ive also done this on top of a wood stove and had the same good results in both pit and sawdust firings.

Experiment experiment experiment. Give it a try with many variables and see what works the best. Dont forget to document and mark what was done to each test piece.

Ive used portland cement as a glaze for many years. Mixing a small amount at a time and using it within an hour works best. I then fire it to c10 and it looks quite similar to a runny ash glaze. Portland is comprised of lime, magnesium, iron ox, and silica. Like Callie said its not something you want to mix alot of because it sets fairly fast.

Ive found out thru experience thats its not the glaze fit but rather the clay body that cant handle the sudden temp shock. Thru research and long conversation with Tony at digitalfire we came to the conclusion thatthe clay body I was using had an unusualy high amount of silica.... micro crystalline silica. A change in the Hawthorn clay ore body prooved to be the culprit. This led me to completely change the clay body Im currently making and using now. With the clay body I have now I can take a mug straight from the freezer and pour in boiling water with no detrimental effects...

Yep an old modified plaster mixer outside and a pugmill. The clay ingredients from my formula are weighed out in proportion and put into the mixer in 100 or 200lb batches and dry mixed for a few minutes then water is added. Clay pulled out and put in 40 gal trashcans and wheeled inside and run thru the pugmill. Pugs of clay are placed in another trashcan and covered with plastic at each layer. Been doing it for years. I once bought a box of clay in the late 80s but none since.

Hi NancyE Well Ive been formulating and mixing my own clay body for ever.. its just part of the potter lifestyle for me. I do have a large converted mixer that will mix about 200lbs at a time and then run it thru a pugmill. I enjoy the process and although its an all day affair to mis and pug 800lbs its therapeutic for me. And im still doing it in my 60's so it can be done.

It seems that the ore body being mined has changed somewhat. I figure that the tile and paint industries are not having problems with the composition so they dont really give a hoot. I have switched all my glazes that contained custer to the G200eu with no problems whatsoever because of how "dirty"...for lack of a better term custer has become.

My guess is that its rutile.

Ive used a high fire stoneware or porcelain with very fine grog- bisque fired only and then some cork backing to prevent moisture from reaching furniture.

Its plain and simple. You just need a new Dr.

Ive used a bit of bleach added to the clay in the pugmill....to kill the bacteria IF it becomes unbearable. On the other hand the bacterial breakdown of organic matter adds plasticity.

They will for the most part BUT as always test test test. Wood firing is such a harsh "dirty" environment and its difficult to control the amount of reduction as each time the kiln is stoked it goes into heavy reduction and then moves to a more neutral stage. this will effect glazes in different ways early inthe firing but more so after the melt. Ive searched for years to get good stable glazes that endure the nature of wood firing.

This looks like delamination bloating. Have you broken the piece to see if theres a bubble or void?

Water lines are put in at 4ft here in northern NM. Ive seen frozen ground 3ft deep. Cold? Zone 5 so it can and has got down to 20 below zero f. Dry? Some winters we get plenty of snow others minimal. Ive seen it snow in December, rain in January and back to snow in February so we have the wackiest of weather. So Gregg... what type of plants are you using these collars for?

I use a Cerdec inclusion red that I use straight on a porcelain. basically i wet my finger and rub the porcelain and the dab my finger into the cerdec and then rub onto the wet porcelain. Then bisque fired and glazed with a clear and fired to c10. It remains really red. You can see the cerdec red in the gums. i do it this way because it would be almost impossible to do it after the piece is built and saves me a huge amount of frustration.

I get my wood from a small lumber mill here. It comes in a 1 cord bundle and consists of small strips, an average of 1inx2in by 8ft. Cut into thirds its perfect for tossing into my fireboxes. Its pine so it burns very fast and with a long flame and doesnt have lots of bark which is what I prefer. .. it keeps the glazes much cleaner. if you want ash buildup use larger pieces with bark which prolong the firing allowing more time for ash to settle on shoulders. Keeping in mind that the ash wont begin to melt till way late in the firing. Oh and here in SF county a kiln is not considered open burning. Its more along the lines of a wood stove and is not subject to the burn bans.. this info from the fire chief who showed up during a firing many years ago. But check it out in your area for yourself.

One thing to think about is that wood fired kilns are unbearably hot to be around in the warmer months. Mine is fired in the colder months of nov thru mar. I considered this when I built mine and went with a large size to accommodate a large amount of wares. About ash buildup. Choose woods with a lot of bark attached . The bark is where most of your fly ash will come from. PM me José and Ill send some pictures of mine.

A few years back I installed a bathroom vent fan in the wall. It moves a few hundred cubic feet of air per hour and its on when Im doing anything in the studio. It keeps the air fairly clean and I figure its better than nuthin.

Minspar200 is a soda feldspar whereas Custer is a potash feldspar. ....maybe someone knows of a substitute? Are you asking because its not accessible to you?

Any easier? Dont know. I formulate and mix my own clay and after its mixed its run thru the pugmill. It takes about 2hrs to run about 600lbs. Its fairly good about me feeding and not having to push the clay too hard down the hopper.

I have the smaller shimpo nra04. 4 bolts come out and the barrel comes off. takes about 5-10 minutes max to clean it.

Iron oxide is the main colorant in practically every glaze i make. Rutile would come second not as a colorant but just for the effect it has on glazes. 3rd cobalt ox or carb.

Overfiring causes the clay body to bloat. If you have not burned out all the organic material in the bisque this will also rear its ugly head in the glaze firing as bloating. .nothing can remedy the bloating in the glaze firing if you havent burned out all the organics in the bisque. You can however fire to correct temp of clay and the reduce temp a bit and hold. This will give time for the bubbles in the glaze to pop and heal over while allowing the clay body to mature and finish offgassing. The amount of time is variable but its just a timing issue.... is the body finished offgassing?.. is the glaze fluid enough to heal? Is the glaze fluid enough at the lower temp to heal over? All hard questions that take time and experimenting to figure out. OR you can dump the black clay and get a more suitable clay body for what youre doing. My 2 cents.

I still make my own clay body. I rarely wedge anymore. I figure thats what a pugmill is for. Giffin grip is used on almost every piece made.

Invest in a good mop and mop bucket and use it frequently. Your lungs will thank you.