USG Plaster Slide Rule

Plaster Calculator Update:  1) Specify units in inches or centimeters, 2) Added @nbivins formula (via @jeffcampana‘s). More ideas for improvements?  Let me know in the comments! (link in bio)

Pictured here:  The original “gypsum cement & plaster VOLUME and MIX calculator” from USG with awesome 80’s graphic design. (Courtesy @earlyamericanrobotpottery)

Continue reading “USG Plaster Slide Rule”

Plaster Calculator

Calculate the amount of water and plaster you will need for various solid forms.

Bookmark this link on your phone’s browser for easy access!

The code is open source and available on Github:

Inspired by Keith Simpson’s (@earlyamericanrobotpottery) plaster handout and the USG plaster calculator.

The calculations are from USG (, Keith Simpson (Alfred University), and Andrew Martin (“The Essential Guide to Mold Making & Slip Casting”). 

Continue reading “Plaster Calculator”

Copper Red Biaxial

Attempting a Copper Red with “normal” flux ratio of R2O:RO 0.3:0.7. (Most formulas I’ve seen have higher R2O levels of 0.4:0.6 or more.) Fixed 0.15 B2O, 0.02 SnO2, 0.01 CuO (1% Tin Oxide and 0.35% Copper Carbonate). Fired together to Orton Cone 10 in reduction starting at cone 010 with 30-minute oxidation hold at peak temp. 
This time I’m labeling the X-axis with SiO2:Al2O3 instead of SiO2.  Using the silica:alumina ratio as the axis seems clearer to me.  The Si:Al ratios are 7, 8, 9, 10, and 11.

Continue reading “Copper Red Biaxial”

Saying Goodbye

Saying goodbye to the Alfred University Raw Materials Lab.
I’ve been incredibly lucky to have spent a year at @alfredceramics with @ceramicmaterialsworkshop, @kelleherceramics, @earlyamericanrobotpottery, @corybrownceramics and so many other amazing teachers and students.  Thanks for this opportunity!

#alfred #glaze #glazes#glazerecipes #glazetest #ceramics#pottery #ceramicglazes#glazechemistry #glazechem#glazecalc #glazy

Continue reading “Saying Goodbye”

Fine-tuning a Recipe

Cone 10 Reduction:

Cone 10 Oxidation:

Creating a small Si:Al biaxial test to “fine-tune” a recipe, in this case Reitz Purple.
Using the Glazy calculator, four “corner” recipes were created.  Volumetric blending using a syringe was used to create the intermediary glazes.  Tests fired to Orton Cone 10 in both oxidation and reduction.  For more information, see:

#glaze #glazes #glazerecipes#glazetest #ceramics #pottery#ceramicglazes #glazechemistry#glazechem #glazecalc #glazy

Continue reading “Fine-tuning a Recipe”

Harlan House Glaze Tests

Absolutely beautiful results from tests of Harlan House’s recipes.

Pictured here are tests of Harlan’s Jun, March Crackle, HH Shino and HH Celadon.  Both March Crackle and HH Celadon have lovely satin surfaces, while the Jun is one of the best I’ve seen, falling neatly in the same high-silica “Jun” region as the ancient Chinese originals. All tests fired to Orton cone 10 in reduction atmosphere starting at cone 010.

Continue reading “Harlan House Glaze Tests”

“My Work, My Way” by Harlan House

Newly-published book and recipes from Harlan House!

Earlier this year, the pioneering ceramicist Harlan House published “My Work, My Way: Fifty Years in the Studio”. Part autobiography, part studio guide, Harlan’s lovely stories are interspersed with technical tips, special techniques, and recipes he developed over decades.  Harlan is generously offering his book as a free download, and he has allowed me to publish his recipes on Glazy.  Thanks so much, Harlan!

Download “My Work, My Way”:

Glazy Collection of Harlan House’s Recipes:

Harlan’s Videos:

Harlan on Facebook:

#glaze #glazes #glazerecipes#glazetest #ceramics #pottery#ceramicglazes #glazechemistry#glazechem #glazy #harlanhouse

Continue reading ““My Work, My Way” by Harlan House”

Rare Earth Glazes in Different Lighting

Some of your requested my previous tests of Erbium Oxide, Neodymium Oxide, and Praseodymium Oxide in Oxidation at Orton Cone 6.

Here are tests using my Cone 6 base, Celadon Clear, on Standard #551 porcelain.  Two sets of photos, one in natural window light and the other in fluorescent light with appropriate adjustments to white balance.  The color differences between light sources are more prominent in person.  All recipes and photos available on

@ceramicmaterialsworkshop just posted some excellent tests by @laura_rainbowyoda showing the influence of different Alkaline Earth Fluxes on the color and quality of glazes with Rare Earth additions.

Continue reading “Rare Earth Glazes in Different Lighting”