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Tony Hansen's Thousand-Post TimeLine

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


With porcelains, poor plasticity gets worse at the leather hard stage

This porcelain becomes quite brittle as it gets stiffer making it difficult to make these cuts in the foot ring. This creates extra sponging work when it is dry. It also means that dry strength will be low. Porcelains do not need to be this way, plenty of white burning bentonites are available (although they increase cost).

Tuesday 25th October 2016

Laguna B-Mix on Steroids! I have wedged in 10% and 20% Plainsman P.E.S.

Both pieces have a transparent glaze, G1947U. The bar in the front is PES (Performance Enhancing Substance)! PES is made from 50:50 Plainsman A1 and St. Rose Red, it behaves like a red fireclay. BMix has some specks anyway, so why not concentrate them into some awesome aesthetics? The addition does ... more

Tuesday 25th October 2016

Now that is a translucent porcelain!

These are two cone 6 transparent glazed porcelain mugs with a light bulb inside. On the left is the porcelainous Plainsman M370 (Laguna B-Mix 6 would have similar opacity). Right is a zero-porosity New Zealand kaolin based porcelain called Polar Ice (from also)! The secret to ... more

Tuesday 25th October 2016

Alberta and Ravenscrag Slips on two cone 10 reduction whiteware bodies

Laguna B-Mix (left) and Plainsman H570 (right). They are fired to cone 10R with pure Ravensrag Slip on the inside and a 50:50 mix of Ravenscrag and Alberta Slips on the outside.

Tuesday 25th October 2016

Can a decal firing melt a glaze? Yes!

Typical zero-boron high temperature glazes will not soften in a 1500F decal firing. But low temperature glazes will (especially those high in boron). Even middle temperature ones can soften. G3806C, for example, is reactive and fluid, it certainly will. Even G2926B, which has high Al2O3 and SiO2, ... more

Monday 24th October 2016

Cone 6 rutile floating blue effect lost. Then regained.

Left: What GA6-C Alberta Slip rutile blue used to look like. Middle: When it started firing wrong, the color was almost completely lost. Right: The rutile effect is back with a vengeance! What was the problem? We were adjusting firing schedules over time to find ways to reduce pinholing in other ... more

Thursday 20th October 2016

Rutile blue glaze effect completely lost! A temporary solution.

Left: 4% rutile in the Alberta Slip:frit 80:20 base. This glaze has been reliable for years. But suddenly it began firing like the center mug! Three 5 gallon buckets of glaze (of differing ages) all changed at once. We tried every combination of thickness, firing schedule, clay body, ventilation, ... more

Thursday 20th October 2016

Underglazes, engobe, a good transparent glaze and cone 03. Life is good!

The white engobe was applied by pouring at leather hard stage. The underglazes were also painted on at leather hard. The mugs were then dried, cleaned, bisque fired, dipping in clear glaze and final fired to cone 03. The clay and engobe have frit additions to make them vitrify at low temperatures.

Thursday 20th October 2016

Blistering in a cone 6 white variegated glaze. Why?

This glaze creates the opaque-with-clear effect shown (at cone 7R) because it has a highly fluid melt that thins it on contours. It is over fired. On purpose. That comes with consequences. Look at the recipe, it has no clay at all! Clay supplies Al2O3 to glaze melts, it stabilizes it against running ... more

Thursday 20th October 2016

Does it matter which transparent glaze you use over underglazes? Yes.

These porcelain mugs were decorated with the same underglazes (applied at leather hard), then bisque fired, dipped in clear glaze and fired to cone 6. While the G2926B clear glaze (left) is a durable and a great super glossy transparent for general use, its melt fluidity is not enough to clear the ... more

Thursday 20th October 2016

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What people have said about digitalfire

• You have such a goldmine of information available on your Digitalfire website and I am asking your permission to, not only use some of it, but to direct the students to your website for more info than I could ever convey.

• Tony Hanson is like the person that is always waiting to answer my questions. He is very thoughtful and quick with response. I wish he was my neighbor.

• Your resources are truly amazing and as an ex electronic engineer (now a potter), I really am impressed with your analytical approaches. Your site is almost a complete college level course on pottery (less the throwing & handbuilding). Thank you for your wonderful contributions.

• I'm trying to access a great article on deflocculation. I have formulated so many casting slips over the years with the help of what I learned in that article and on this site.

• I have a background in Geology (BS-1973-New Mexico Tech), and with a few other degrees here and there - and have been doing quite a bit of Pythoning, and hanging-around my wife who does (I think (but then, of COURSE I am biased)) terrific pots... I am always interested in what she does with glazes (especially when I see the mineral-names from my Geology days on the bins in her studio... BUT - as an "engineer", sometimes I want 'more' knowledge - and I find your web-site VERY VERY good at that, it tells me a lot of things - gives me 'value added' and 'information' that I haven't found elsewhere! Especially when I think about 'geo-chem'.

• I have thoroughly enjoyed the articles on your web site.

• is a fantastic resource!

• I have visited your site many times. We have the largest department in new england at the moment. I invited students to visit the school library to access your site directly for all its wisdom! You do far more good than you realize, fellow mud-diver.

• I enjoy and appreciate your work very much.

• Many Solution Regarding Ceramic Problems Got From Your Website.Thank You Very Much.

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