Javascript must be enabled in the security or content
settings of your browser for this site to work properly

To learn more about cookies search for HTTP cookie at wikipedia.com





Click here for information about DIGITALFIRE Corporation

Tony Hansen's Thousand-Post TimeLine

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

   All

Thermal expansions for body, engobe and glaze in ceramic tile

The upper line is the body. The center line is the engobe. The lower line is the glaze. The ceramic tile industry is very conscious, not only of glaze-fit but also engobe-fit. Engobes (slips) are employed to cover brown or red burning bodies so they glaze like a porcelain. Typically technicians tune ... more

Wednesday 18th January 2017

The high thermal expansion of a low-fire talc body

Talc is employed in low fire bodies to raise their thermal expansion (to put the squeeze on glazes to prevent crazing). These dilatometer curves make it very clear just how effective that strategy is! The talc body was fired at cone 04, the stoneware at cone 6. The former is porous and completely non-vitreous, the latter is semi vitreous.

Wednesday 18th January 2017

The rutile mechanism in glazes

2,3,4,5% rutile added to a 80:20 mix of Alberta Slip:Frit 3134 at cone 6. This variegating mechanism of rutile is well-known among potters. Rutile can be added to many glazes to variegate existing color and opacification.

Sunday 15th January 2017

Two glazes. One crawls, the other does not. Why?

The glaze on the right is crawling at the inside corner. Multiple factors contribute. The angle between the wall and base is sharper. A thicker layer of glaze has collected there (the thicker it is the more power it has to impose a crack as it shrinks during drying). It also shrinks more during ... more

Tuesday 3rd January 2017

I have always done it this way. Why is it not working now?

Are you really sure the problem is with the materials? I had been using an 85% Ravenscrag, 15% frit glaze for many years with no crawling problems. But then it started crawling. I tried mixes with new materials and the old ones. Still crawled. The problem? What was I thinking? An 85% clay glaze is ... more

Tuesday 3rd January 2017

A DFAC drying test disk of a terra cotta pottery clay from St. Ignacio, Sinaloa, Mexico

This clay is used by traditional potters in the Mazatlan, Sinaloa, Mexico area. This DFAC test shows a very wide main crack and number of edge cracks. These indicate very high shrinkage and plasticity. Although the clay has some coarser grains that help channel water out, this is a very poor showing ... more

Thursday 22nd December 2016

Slaking. What is that?

A slaking clay (a typlical potters clay). On the left the clay bar has been in the water for around 10 seconds. On the right, after a couple minutes, the rate of slaking has increased dramatically. Within about 5 minutes this bar will disappear into a pile on the bottom. Slaking happens most quickly ... more

Wednesday 21st December 2016

Example of a data sheet for Copper Carbonate

Notice it does not quote the amount of CuCO3, just Cu metal. It also does not quote LOI percentage (weight loss on ignition, it will be more than 25%). Theoretical copper carbonate is 71.94% CuO (sourced by a mix of copper carbonate and carbonate hydroxide). CuO is 79.9% copper and 20.1% oxygen. ... more

Saturday 10th December 2016

An extreme extremely runny glaze at cone 6. Is there a cost?

This recipe melts to such a fluid glass because of its high sodium and lithium content coupled with low silica levels. Reactive glazes like this produce interesting visuals but these come at a cost that is more than just the difficulty in firing. Recipes like this often calculate to an extremely ... more

Sunday 4th December 2016

The blue color in this porcelain develops more as maturity increases

These fritted porcelain bars are fired at cone 06, 04, 03 and 02 oxidation (bottom to top). The body contains 0.2% blue stain. Notice that almost no color develops at the lowest temperature. Glass development is needed.

Friday 2nd December 2016

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

Login to your online account

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. Download it from the Files panel in your account at Insight-live.com (no extra charge).


How to reach us

From within your account at Insight-Live.com or

What people have said about digitalfire

• However I do believe you have the most comprehensive information anywhere in the world, and I would not hesitate to contact you for any information I required for Ceramic Glaze. I will also refer my associates to you if ever they require assistance.

• Who needs sex when you have digitalfire.com!

• Thanks for the great resource Digitalfire is. I could not make our studio glaze without it.

• Thanks a lot for this sea of knowledge.

• Thank you for all the wonderful work you do for the ceramic community.

• I'm still reading about expansion and some of what you explained to me is in this article by digital ... so much lay men terms and analogies makes its more viewable to the mind and understandable... thanks - I continue to say thanks... Tony.... :)

• First of all I'd like to congratulate you for the incredible source of information and Guidelines in your website. We are changing our fast-firing process (cold to cold in 4.5 hours) to a slow-firing process (cold to cold in 24.0 hours) and all our glaze formulas have lost their acid resistant characteristic, after dipping in 24 hrs at Ph1.3.

• I have visited your website for many years to get ceramic information - your website is excellent ... Thanks again for all the great info on your website - hopefully one day I can repay you for your outstanding resourse.

• Great customer service!!

• After perusing your site for some time, I am really getting the sense of what a valuable resource it is. Thank you for it.


To see more (at random) refresh this page

DigitalFire Logo

1 - 530 Allowance Ave, Medicine Hat, Alberta, Canada T1A 3E3
(403) 527-7508
Privacy Policy