Click here for information about DIGITALFIRE Corporation

Monthly Tech-Tip from Tony Hansen

I will send practical posts like these (from thousands I maintain). No ads or tracking. We are troubleshooting the confirm email, for now you will be subscribed immediately (the first monthly email will provide one-click unsubscribe).


Blog

First printed mold half of coffee mug is ready

3D printed mug mold

This is part of a project to make a slip-casting mold for a coffee mug. In the slicer, I split the print into two pieces 22mm up from the base. This enabled doing the bottom section right side up and the top one upside down. That drastically cut the amount of support generated (and thus printing time). I scotch-taped the two halves together and filled it with plaster to produce a rigid block mold. The two halves fit so precisely it is difficult to tell where they join. The big benefit of printing it upright like this is that the all-important front face is very flat (there is some warpage on other parts but that does not matter).

Context: Slip Casting Mold for..

Wednesday 20th March 2024

3D design, printing and use of a test bar mold

SHAB mold for casting clays

This is for making test bars of slip casting clays bodies for use in the SHAB test (to measure drying shrinkage, firing shrinkage and fired porosity). I designed it in Fusion 360 and 3D printed the rails and case mold. I poured plaster into that to make the two plaster working mold halves (top right). The funnels provide a reservoir so the bars be cast solid. This mold can produce a set of three bars in less than an hour.

Tuesday 19th March 2024

Lead bisilicate with his ugly borosilicate cousins at a cone 05 party

Boron and lead transparent glazes on terra cotta

The middle front mug is glazed with an 85:15 lead bisilicate:kaolin mix, the G3971 recipe. It is an absolutely "knock your socks off" crystal-clear hyper-glossy surface that transmits the terra cotta color beautifully regardless of whether the clay is smooth or coarse or the glaze thick or thin (this one was applied as a brushing glaze in three coats on L215). My lead testing kit passes it with no detectable lead release. The other pieces are done using brush-on versions of boron-based clear glazes (commercial and made from a recipe). At almost any thickness and whether on L215 or L4170B clouding occurs. The worst one is a commercial three-coater on the right, the best is G1916W (it has 2% added iron as a fining agent for the micro-bubbles). My terra cotta plan: Glaze the inside functional surfaces with that and the outsides with the leaded one (and using a kiln exhaust system).

Context: Lead Bisilicate Frit, A lead bisilicate frit.., 2 iron oxide in.., Boron blue in low.., A cure for long-time.., Is it impossible to.., Thick application clouds a.., Lead in Ceramic Glazes..

Sunday 17th March 2024

Use the same runny glaze as its own catch glaze

As runny glaze as its own catcher

This is G3948A, a super runny cone 6 iron red glaze. The clay body is M340. This glaze has to be runny, applied thickly enough, be held at temperature and cooled slowly to achieve this visual effect. When applied at the needed thickness it will run off the ware onto the kiln shelf during firing. Why has that not happened? A catcher glaze on the lower section. In this case, the catcher is the same glaze. On the left, the bottom half of the mug has just been dipped into the glaze quickly, giving a layer that is too thin to achieve the red effect. That dried within a few seconds and enabled pushing the top half down into the dipping glaze for twice as long (the inside has a liner glaze and is waxed up to the rim). The upper section glaze is guaranteed to run and the bottom is not thick enough to run. The result is complete blurring of the dividing line and coverage that looks natural and flawless.

Context: Stop a runny glaze.., Catch Glaze

Tuesday 5th March 2024

ChatGPT woke me up about making my own frits.

Frit melted in crucibles

I asked ChatGPT this question and got a very thoughtful answer that seems to confirm what I have observed in smelting material mixtures into ingots in alumina and zircon lined slip cast crucibles. The mixtures are melting well in the test crucibles (the upper one was fired at cone 4, the lower one at cone 6). But there are issues. There does appear to be phase separations. And bubble froth at the top. For some compositions alumina works better as a liner, for others zircon. We are getting closer to trying larger multi-kilogram batches and ball milling so time will tell.

Context: Crucible with alumina oxide.., AI in Ceramics

Friday 1st March 2024

Paint another layer onto a fired glaze? Yes. With CMC gum.

The cone 6 mug on the left has the G3933A glaze, applied as a dipping glaze. It turned out poorly - crawling from corners and looking thin and washed out. I made a brushing glaze version of this (which adds 1.5% CMC gum), I keep it around for this very purpose. It has a high specific gravity (unlike commercial ones that have high water contents - they will run and go on too thin if you try this). Because of the gum it dries hard, there is no shrinkage or cracking. On a second firing, using the C6DHSC schedule again, (mug on the right) the surface is transformed - thicker, more vibrant color (being picked up from the underlying body).

Context: CMC Gum, Six layers 85 Alberta.., Control gel using Veegum.., Convert a pint of..

Wednesday 28th February 2024

Iron red glaze fired at cones 6, 5 and 4

Iron red glaze at cone 6, 5, 4

These mugs are Plainsman Coffee Clay. The glaze on all three is G3948A iron red. They were fired at cone 6, 5 and 4 using the C6DHSC schedule (adjusted for top temperature). As can be seen, the red color depends on the melt fluidity achieved at cone 6.

Context: Same glaze on black.., Iron Red Glaze

Sunday 25th February 2024

Finished cast v1 stoneware beer bottles

Cast ceramic beer bottles

The center bottle is a standard glass one, the other two are ceramic, cast out of the version 1 plaster mold. The stopper fits perfectly. The clay is Plainsman M370 + 10% raw umber, it fires black. The glaze is GA6-B. They were fired using the C6DHSC firing schedule. The slightly larger size will enable inserts at the bases to inlay a logo or other info. These bottles are a testament to how 3D printing and 3D design now make it possible for even casual potters to make pieces never before practical or even possible.

Context: Slip cast leather-hard full-sized.., Ceramic beer bottles with.., Beer Bottle Master Mold..

Saturday 24th February 2024

Version 2 ceramic beer bottle block mold

Casting a rubber case mold for the beer bottle

This time I printed the block mold, rather than the case mold, in six pieces on my consumer 3D printer.
Top: I printed the two halves upright (creating them in the slicer rather than Fusion 360). Because the print lines run concentric the quality is so much better than the previous version printed flat. The ribbing inside made the halves strong so they did not go out of shape when filled with plaster (to give them weight).
Second: The mold halves were simply laid against each other - they mated perfectly (and stayed in place because they are full of plaster). The four rails were then clamped in place.
Third: The PLA was soaped (using Murphy's Oil Soap) and rubber poured in (Smooth-On PMC-746). The next day it easily pulled out.
Fourth: The finished rubber case mold. The sides are pretty flabby so I made them rigid using the four rails (placed upside down).
Right: Using a plaster mold created from this rubber case mold I slip-casted a bottle using my L4768D recipe, glazed it with GA6-B and fired it at cone 6.

Context: Slip cast leather-hard full-sized.., Beer Bottle Master Mold..

Saturday 24th February 2024

This impossible AI porcelain mug suggests it is actually learning

A strange AI porcelain mug

Consider these porcelain mugs I "imagined" at MidJourney.com. At first, they look pretty typical but take a closer look at the one in the middle. The floral design on the one behind morphs into the actual 3D shape on the one in front. This seems like an indication that the AI is actually drawing these, not just plagiarizing them from its scraping activities online. The #aiart, #aiartwork, #aiartcommunity and similar hashtags generate millions of posts (albeit of questionable taste), but they are a harbinger of things to come.

Context: These pots are not.., AI in Ceramics

Saturday 24th February 2024

Contact Me

Use the contact form at the bottom on almost all the pages on this site or let's have a together.

Other ways to Support My Work

Subscribe to Insight-Live.com. It is about doing testing and development, not letting the information slip away. Starts at $15 for 6 months.

Tony Hansen
Follow me on

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

Login to your online account

Chemistry plus physics. Maintain your recipes, test results, firing schedules, pictures, materials, projects, etc. Access your data from any connected device. Import desktop Insight data (and of other products). Group accounts for industry and education. Private accounts for potters. Get started.

Conquer the Glaze Dragon With Digitalfire Reference info and software

Download for Mac, PC, Linux

Interactive glaze chemistry for the desktop. Free (no longer in development but still maintained, M1 Mac version now available). Download here or in the Files panel within your Insight-live.com account.


What people have said about Digitalfire

  • We have been aware of your company and website for many years and see it as a model in its approach to educating makers about the processes involved in making/drying/firing. You teach them to take responsibility for their work process rather than blaming the product.
  • Thank you for your wonderful site i am new to home made glazes and am teaching myself... your site is so help full thank you.
  • In the meantime I downloaded the book. It was an interesting reading without any stop. That was exactly what I was looking for. I will start my work after my summer vacation and see what I will be able to achieve. Based on the given information I hope to be able to create something.
  • What a great site! Such a wealth of information. The thing I appreciate most about the site is the orderly and thoughtful and thought through approach to glazing. We are learning and earning potters, learning the craft and acquiring some income from it as we grow, working with cone 6 clays and glazes. I've been visiting your site frequently recently because we are starting to mix our own glazes, and we wanted to be able to incorporate the textures, surfaces and colors of our choosing, not hit or miss due to trying untold numbers of blind recipes. I've found that even a glaze that I've seen on someone else's work, using the same glaze mix on my work, does not guarantee the same result in my kiln, due to clay differences, surely, but also how my kiln fires, what temps it reaches, what timing, etc. So we want be able to work out glazes that look and feel the way that we like, in our firing environment, on our clays.
  • 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.
  • I, personally, think Digital Fire's contribution to potters, and the Ceramic industry as a whole, is absolutely awesome, and I thank the gods there are people like you who have the knowledge and energy to provide us simple artist/educators with such exceptional tools.
  • Your work has been incredibly helpful. Magic of Fire especially.

What people have said about Insight-Live

  • I have done production pottery at cone 10 and 5 for 40 years, but during almost of full year of downtime due to COVID, I am exploring low fire terra cotta. Digital fire is an amazing resource. Thank you so much.
  • I want to first tell you that your site is amazing. i love the approach, the attitude, and the incredible information. the fact taht you share so much of your information to the public is truly wonderful. I recenly fell in love with ceramics and set up a home studio.
  • Thank you very much for creating these examples and explanations. I am getting a much better understanding for why Frits are so much better. Now that I am digging into InSight-Live and manipulating the chemistry, this documentation is the main place where I can find the facts and suggestions that help clear up my questions. Thank you for creating such a very practical and wonderful upgrade . The interface is so nice and even forgiving. Thank You Very Much,
  • I am a long time fan. I bought your downloadable book long ago and still refer to it frequently. Has bunches of my notes in it too. It expanded my college training with glaze chem. Appreciate you.
  • It's very impressive work you do. Thanks you for providing it.
  • I wanted you to know that, you have a fantastic program. Every serious potter should use it. And it would be a good starting curriculum for high school and college to learn from. Thanks for, I would imagine, many hours in developing time. Kudos sir. I hope, by God's good will that I will be able to enjoy it for any years to come.
  • And I want to add - you are doing a magnificent job with your webpage. Just unbelievable amount of work and information you put there. I have learned a lot from your webpage. Thank you.



https://digitalfire.com, All Rights Reserved
Privacy Policy

1