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Tony Hansen's Thousand-Post TimeLine

I am the creator of Digitalfire Insight, the Digitalfire Reference Database and Insight-live.com. ... more

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Hand-tooled jigger model vs. 3D-printed and cast

I am creating molds for a casting jiggering process to make mugs. I have a profile drawing I want to match (upper left). The solid model on the left is my first attempt at manual tooling. The metal template was time-consuming to make by hand, it worked poorly (the surface is rough). And the contour ... more

Friday 15th November 2019

The amount of encapsulated stain needed for intense color

This is about 1/2 gallon of glaze with 150 grams of yellow stain ready to mix in. That stain retails for about $30 so its cost alone is about $60 for each gallon (in 2017). But the incredible color it produces cannot be done in any other practical way.

Thursday 14th November 2019

Here is why quartz is good in clay bodies

The piece on the left is 65% ball clay and 35% nepheline syenite. The one on the right is 65% kaolin and 35% nepheline syenite. Both fire vitreous at cone 6. But the glaze is crazing on the kaolin and not on the ball clay. This is because the ball clay contains significant quartz, that raises the thermal expansion and that puts the squeeze on the glaze and prevents the crazing.

Thursday 14th November 2019

A terra cotta body fired from cone 06 (bottom) to 4

Terra cotta bodies are more volatile in the kiln than stonewares. They mature rapidly over a narrower range of temperatures, that process is accompanied by dramatic changes in fired color, density and fired strength. These bars are fired (bottom to top) at cone 06, 04, 03, 02, 2 and 4. This is ... more

Friday 8th November 2019

Four north American ball clays fired to cone 10R, 11 and 10 oxidation

It is amazing now similar different ball clays are. Clearly, soluble salts are an issue with all of them (the brownish scum). These bars are much cleaner on the backsides (since the solubles were left on the surface on the fronts during drying). The drying shrinkages, plasticities and fired maturities are also all remarkably similar.

Thursday 7th November 2019

G2934Y glaze on Standard #112 body at cone 6

Produces an appearance very similar to dolomite-matte-glazed ware fired in cone 10 reduction. The effect would be similar using speckled bodies made by other manufacturers. Pieces made by Tom Friedman.

Thursday 7th November 2019

What has the trust in online recipes come to?

These tests of a recipe called "Strontium Crystal Magic". The potter tried it on different bodies and firings. But instead of producing the magic crystals like the pictures, the surfaces fired totally matte. Reasoning "why would anyone put a recipe on line that does not work", she blamed one of the ... more

Tuesday 5th November 2019

White stain. Does it work?

This is G2934Y matte glaze base with opacifiers added. It has been applied to a dark-burning body to demonstrate the comparative degrees of opacity. The stain is Mason 6700 white stain. While it does not opacify nearly as well as tin or zircon, it does produce a smoother surface.

Monday 28th October 2019

Is it possible to make a thin flat porcelain tile from a plastic pottery body?

Yes. The body is Plainsman M370 (~ 25 silica, 25 feldspar, 30 kaolin, 20 ball clay + talc to tune maturity). It is 3.8 mm thick fired (vs. commercial tiles at 5-7mm). It was rolled (in the plastic state) and dried completely between sheets of plaster board. Bisque and glaze firing were on an alumina ... more

Sunday 27th October 2019

Same body, same glaze, same firing. Why did one crawl?

The body: M370. Glaze: G2934Y (with added green stain). Firing: Cone 6 drop-and-hold. Glazing method: dipping (using tongs). Thickness: The same. The difference: Wall thickness. The one on the right was cast thinner so the glaze took a lot longer to dry (the bisque lacked sufficient absorbency). ... more

Sunday 27th October 2019

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