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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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Example of a logo done using a polymer plate

Example of a logo done using a polymer plate

Polymer plates are used in letter press and can still be purchased online (e.g. boxcarpress.com). Just create the artwork in a vector graphic drawing program and upload it to their website. Press it into a thin slab (using some sort of oil as a parting agent) and then attach that using slip to the ... more

Thursday 17th August 2017

Polymer plates. Great for stamping into clay.

Polymer plates. Great for stamping into clay.

These are samples made by Boxcar Press. They make different depths, you need the 0.047 relief depth. While the others will press a crisp design into the clay, the shallow depth will make it difficult to avoid rubbing out the color from the recesses when you a sponging it off the top. Traditionally ... more

Thursday 17th August 2017

Measure glaze specific gravity with these? Forget it!

Measure glaze specific gravity with these? Forget it!

Glazes need to be gelled, have thixotropy. That means these things won't bob up and down to find the right place. The one on the right is completely useless, the scale is too wide. Most glazes need to be between 1.4 and 1.5 specific gravity (40-50 on this scale). That is like reading seconds on the ... more

Wednesday 16th August 2017

How to make a ceramic time-bomb

How to make a ceramic time-bomb

This mug is pinging loudly and literally self-destructing in front of my eyes! Why? The glaze is under so much compression (the inside is pushing outward, the outside inward). Spiral cracks are developing all the way up the side. Small razor-sharp flakes are shivering off convex contours. Why? I ... more

Tuesday 15th August 2017

Drip glazing and bare outsides: Deceptively difficult.

Drip glazing and bare outsides: Deceptively difficult.

Why? Glaze fit. These are available on Aliexpress (as Drip Pottery) and they are made by a manufacturer that has a dilatometer to precisely match the thermal expansion of the glaze with the body. The inside glaze has to fit better than normal because of the absence of an outside glaze. Too low of a ... more

Monday 14th August 2017

Glaze at 1.7 specific gravity on green-ware. Way too thick!

Glaze at 1.7 specific gravity on green-ware. Way too thick!

This is G2926B clear cone 6 glaze deflocculated with Darvan. Because the Darvan is thinning it, 2.5kg of powder is suspended in only 1100 grams of water (half the normal amount). While the slurry in the bucket flows well and appears like it should work, a one-second dip produces twice the desired ... more

Monday 14th August 2017

Why you should not paint pure stain powders over glaze

Why you should not paint pure stain powders over glaze

On the left is a blue stain, right is a green. Obviously the blue is melting much better, even bleeding at its edges. On the other hand, the green just sits on the surface as a dry, unmelted layer. For this type of work, stains need to be mixed into a glaze-like recipe of compatible chemistry (a ... more

Saturday 12th August 2017

Mug made from a cone 6 black-burning stoneware body

Mug made from a cone 6 black-burning stoneware body

Black burning bodies are popular with many potters. They are normally manufactured by adding around 10% burnt or raw umber to an existing buff-burning cone 6 stoneware. Umbers are powerful colorants, they have high iron and also contain manganese (the latter being the primary source of the color). ... more

Saturday 12th August 2017

Can you make a black-burning stoneware using black iron oxide?

Can you make a black-burning stoneware using black iron oxide?

Iron oxide has been added to a buff burning stoneware clay and samples fired at cone 6. They contain black iron oxide (10%, 5% and 2.5%). Even at 2.5% the raw pugged body is very black and messy to work with. Did they fire black? Or even dark grey? No. We have also tried 20% (mix of black and yellow ... more

Saturday 12th August 2017

This is how New Zealand kaolin powder agglomerates

This is how New Zealand kaolin powder agglomerates

These balls are easily broken down by the propeller in a slurry mixer. But they do not break down easily in a dry mixer, even when in a mix with other materials (like silica and feldspar). They just bounce around on a vibrating screen. That means that without some sort of finishing device in the dry ... more

Wednesday 9th August 2017

Test, Document, Learn, Repeat in your account at insight-live.com

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Chemistry plus physics. The on-line successor to desktop Insight. Get an account for as little as $15. It does so much more.

Conquer the Glaze Dragon With Digitalfire Reference info and software

Still available for Mac, PC, Linux

Interactive glaze chemistry calculations.


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What people have said about digitalfire

• First I want to thank you for creating and maintaining your web site. I started as a potter and moved into ceramic engineering over the course of my career and your web site has helped me all the way. Currently I am working on digital ceramic ink jet printing.

• Thank you for all the great work you have done and the tremendous contributions you have made to the ceramics community.

• Your web site is wonderful. You guys are my knight-in-shinning-armor to slay that dragon. Learned more about glaze chemistry on your web page than in a graduate program at RISD.

• Just wanted to tell you I just found your site and find it extremely useful. Got it bookmarked and will be referring to it frequently. Great job! Thank you!

• Abundant thanks on you how much the huge information and useful for me and for domain of pottery and the academic arts and the students.

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• First of all, I want you to know what an incredible resource your work has been for me the past several years.

• Being new to this I was fascinated by the amount of information contained on your website and impressed by what you are willing to share.

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