Author archive for Derek

  • Software

    In Praise of Plain Text

    Note: This is my first post made using the new WordPress Gutenberg editor.

    I’ve spent the past day trying to export my mother’s Outlook email archives to a format that I can import into a new Gmail account I’ve set up for her.  It’s been a surprisingly frustrating ordeal given that her outdated Outlook 2007 installation is somehow slightly corrupted and Thunderbird is getting stuck importing the PST files.  The only option that’s worked is propriety software that will cost me $30 for a license that I’m too stubborn to buy.

    I can’t but help think of the Clayart email discussion list, one of the oldest and perhaps most popular lists used by ceramicists throughout the years.  The list archives have been converted to HTML web pages and posted on a number of websites and platforms throughout the years, most notably http://potters.org  These archives proved extremely valuable to me during my time in Jingdezhen when I was researching ceramics techniques and recipes.  The fact that the full Clayart archives are available in human-readable text formats like mbox and HTML means that they are hardy– much less fragile than proprietary binary formats like Outlook PST.

    It just happens that I’ve also been thinking of the best data format for exporting Glazy’s ceramic glaze recipes.  Throughout the years there have been a number of glaze calculation programs that have come and gone.  Some of these programs used binary file formats that can no longer be read, while luckily others used plain-text file formats.  The best example is probably GlazeChem, which used a simple plain-text format that looked like this:

    name   = Pebble Sculpture Glaze
    index  = 
    date   = 12/16/2012
    source = 
    type   = 
    range  = 03
    firetype     = Oxidation
    color        = White
    vistexture   = Mottled
    quality      = Lichen
    transparency = Translucent
    xtals        = 
    bubbles      = 
    flow         = 
    durability   = 
    flaws     = 
    tested    = 
    imagefile = 
    notefile  =  
    limform   =  
    by_vol    = n
    batchsize = 0
    component = Magnesium carbonate
    amount    = 35.7
    component = Lithium carbonate
    amount    = 7.1
    component = Borax
    amount    = 35.7
    component = Gerstley borate
    amount    = 21.5
    var  = |+ copper carb 2.9 + cobalt carb 0.3 - mottled semi-gloss blue-green
    var  = |+ rutile 6 - waxy mottled yellow-green when over black (iron) slip
    var  = |+rio 3.2 = Mottled brown
    var  = |+Zircopax 5.2 = Smoother mottled brown when over black (iron) slip
    var  = |+ 1.5 Chrome = over black (iron) slip mottled brown and green
    note = |Tested by Rhonda Chan.

    Although the GlazeChem software is no longer maintained, luckily a number of ceramicists exported their recipes and posted them online.  The most notable collection of GlazeChem archives is on Linda Arbuckle’s website:  http://lindaarbuckle.com/arbuckle_handouts.html  When seeding the original Glazy database, it was trivial to write a script to import the GlazeChem archives into the Glazy Mysql database.  More importantly, anyone can just download the articles and read the original plaintext recipes.

    Another notable file format for glaze recipes is from Digitalfire and uses XML:

    <?xml version="1.0"?>
    <recipes version="1.0" encoding="UTF-8">
    <recipe name="Cone 6 Ultraclear Glaze for Porcelains" keywords="Substitute for low expansion cone 6 G1215U, this sources MgO from talc instead of a frit" id="106" date="2015-10-30" codenum="G1216M">
    <recipelines>
    <recipeline material="Minspar 200" amount="8.600" unitabbr="kg" conversion="1.0000" added="0"/>
    <recipeline material="Ferro Frit 3134" amount="23.200" unitabbr="kg" conversion="1.0000" added="0"/>
    <recipeline material="Wollastonite" amount="15.200" unitabbr="kg" conversion="1.0000" added="0"/>
    <recipeline material="EPK" amount="24.800" unitabbr="kg" conversion="1.0000" added="0"/>
    <recipeline material="Talc" amount="4.300" unitabbr="kg" conversion="1.0000" added="0"/>
    <recipeline material="Silica" amount="23.800" unitabbr="kg" conversion="1.0000" added="0"/>
    <url url="https://www.digitalfire.com/4sight/recipes/cone_6_ultraclear_glaze_for_porcelains_106.html" descrip="Recipe page at digitalfire.com"/>
    </recipelines>
    <urls/>
    </recipe>
    </recipes>

    As with the GlazeChem file format, Digitalfire’s XML format is very easy to read either by humans or import scripts.

    Glazy uses a JSON (JavaScript Object Notation) lightweight data-interchange format for communication between server and client. It’s similar to the XML format used by Digitalfire, but drops the opening and closing tags and just uses names & values.

    {
        "data": {
            "id": 3262,
            "parentId": null,
            "name": "Leach 4321 +1% Red Iron Oxide",
            "otherNames": null,
            "description": "The classic Leach clear plus iron oxide.",
            "isAnalysis": false,
            "isPrimitive": false,
            "isArchived": false,
            "materialStateId": 2,
            "materialStateName": "Production",
            "materialTypeId": 490,
            "baseTypeId": 460,
            "materialType": {
                "id": 490,
                "parentMaterialType": {
                    "id": 460,
                    "parentMaterialType": {
                        "id": 100
                    }
                }
            },
            "fromOrtonConeId": 34,
            "fromOrtonConeName": "10",
            "toOrtonConeId": 34,
            "toOrtonConeName": "10",
            "surfaceTypeId": 8,
            "surfaceTypeName": "Glossy",
            "transparencyTypeId": 4,
            "transparencyTypeName": "Transparent",
            "colorName": "transparent",
            "hexColor": "ffffff",
            "thumbnailId": 518,
            "ratingTotal": 0,
            "ratingNumber": 0,
            "ratingAverage": "0.00",
            "isPrivate": false,
            "createdByUserId": 7,
            "createdAt": "2015-10-14T13:25:44",
            "updatedAt": "2015-10-14T14:44:52",
            "materialComponentTotalAmount": 101,
            "atmospheres": [
                {
                    "id": 3
                }
            ],
            "materialComponents": [
                {
                    "percentageAmount": "40.0000",
                    "isAdditional": false,
                    "material": {
                        "id": 15892,
                        "name": "Potash Feldspar (Zheng Yi SK7)",
                        "isAnalysis": false,
                        "isPrimitive": true,
                        "isPrivate": true,
                        "materialStateId": 2,
                        "analysis": {
                            "percentageAnalysis": {
                                "SiO2": "70.1200",
                                "Al2O3": "16.5200",
                                "Na2O": "2.9800",
                                "K2O": "9.5000",
                                "MgO": "0.0200",
                                "CaO": "0.2300",
                                "TiO2": "0.0100",
                                "Fe2O3": "0.0500",
                                "loi": "0.2600"
                            },
                            "umfAnalysis": {
                                "SiO2": "7.6011",
                                "Al2O3": "1.0553",
                                "Na2O": "0.3132",
                                "K2O": "0.6569",
                                "MgO": "0.0032",
                                "CaO": "0.0267",
                                "TiO2": "0.0008",
                                "Fe2O3": "0.0020",
                                "SiO2Al2O3Ratio": "7.2028",
                                "R2OTotal": "0.9701",
                                "ROTotal": "0.0299"
                            },
                            "molPercentageAnalysis": {
                                "SiO2": "78.6924",
                                "Al2O3": "10.9253",
                                "Na2O": "3.2421",
                                "K2O": "6.8006",
                                "MgO": "0.0335",
                                "CaO": "0.2766",
                                "TiO2": "0.0084",
                                "Fe2O3": "0.0211"
                            },
                            "formulaAnalysis": {
                                "SiO2": "1.1670",
                                "Al2O3": "0.1620",
                                "Na2O": "0.0481",
                                "K2O": "0.1009",
                                "MgO": "0.0005",
                                "CaO": "0.0041",
                                "TiO2": "0.0001",
                                "Fe2O3": "0.0003"
                            },
                            "weight": "0.0000",
                            "oxideWeight": "647.6175"
                        },
                        "thumbnail": {
                            "id": 4991,
                            "materialId": 15892,
                            "title": "",
                            "description": "",
                            "dominantRgbR": 222,
                            "dominantRgbG": 212,
                            "dominantRgbB": 202,
                            "dominantHexColor": "ded4ca",
                            "secondaryRgbR": 153,
                            "secondaryRgbG": 129,
                            "secondaryRgbB": 109,
                            "secondaryHexColor": "99816d",
                            "filename": "15892.5a6bafa381899.jpg",
                            "isPrivate": false,
                            "createdByUserId": 7,
                            "createdAt": "2018-01-26T22:45:57",
                            "updatedAt": "2018-01-26T22:45:57"
                        }
                    }
                },
    ........ etc. ......
            }
    
        }
    
    }

    But I don’t think JSON is the best way for storing and archiving recipes.  Below is my current proposal for Glazy recipe import and export.

    Steps to import:

    • If line equals “RECIPE:”, end current recipe or material and begin importing a new recipe or material.
    • Indentation and whitespace doesn’t matter (except for spaces between words).  As plaintext recipes are copied & pasted or converted to other text formats over and over again, it’s likely that whitespace will be modified.  For example, loss of indentation.  The data should still be readable even if this occurs.
    RECIPE:
    Name: Leach 4321 +1% Red Iron Oxide
    Other Names:
    Orton Cone: 9-10
    Type: Glaze > Iron > Celadon
    State: Production
    Surface: Glossy
    Transparency: Transluscent
    Description: The classic Leach clear plus iron oxide.
    INGREDIENTS:
        40    Potash Feldspar (ID: 15892)
        30    Silica (ID: 15400)
        20    Whiting (ID: 15457)
        10    Kaolin (ID: 15288)
        +1    Red iron oxide (ID: 15387)
    METADATA:
        ID: 3262
        Parent ID: 
        Analysis: False
        Primitive: False
        Archived: False
        Created By: Derek Au
        Created By User ID: 7
        Created At: 2015-10-14
        Updated At: 2015-10-14
    PERCENTAGE ANALYSIS:
        SiO2: 62.15
        Al2O3: 10.52
        Na2O: 1.18
        K2O: 3.76
        MgO: 0.00
        CaO: 11.20
        TiO2: 0.00
        Fe2O3: 0.96
        LOI: 10.08
    UMF ANALYSIS:
        R2O/RO:
            Na2O: 0.07     
            K2O: 0.15
            MgO: 0.00
            CaO: 0.77
        R2O3:
            Al2O3: 0.40
        RO2:
            SiO2: 4.00
        OTHER:
            TiO2: 0.00
            Fe2O3: 0.02
        SiO2:Al2O3 Ratio: 10.02
        R2O:RO Ratio: 0.23:0.77
  • Work

    12th Annual Simple Cup Show

    This year I was invited to participate in the Simple Cup Invitational at KOBO Gallery (https://koboseattle.com/).

    2 “Painted” cups in porcelain with Celadon glaze, cone 10 reduction firing, October 2018.

    2 “Splashed” cups in porcelain with Tenmoku glaze and Iron Red splashes, cone 10 oxidation firing, October 2018.

  • Glazes

    Iron Saturate Glazes

    During the next few days I’ll be releasing a series showing how to create a glaze using Glazy and volumetric blending.

    The first step is familiarizing oneself with the glaze type. For this demonstration I’m interested in creating a Cone 10 Iron-Saturate Red microcrystalline glaze also known as “Kaki”, “Tomato Red”, and “Persimmon”. Some historically examples are Chinese Song Dynasty Ding Persimmon-glazed wares as well as many of Shoji Hamada’s works.

    For each search, Glazy shows Recipe Cards with photos as well as a Stull Chart. The Stull Chart has five major regions: Unfused, Matte, Semi-Matte, Bright/Gloss, and Under-fired. There is another area, Crazed, that overlaps the other regions. In the next step, I will create a Biaxial Test using the Stull chart as a guide.

    From the analyses of Iron-Saturate glazes in Glazy, it is not clear what the ideal amount of Silica and Alumina (and the Si:Al ratio) should be. So our first step will be to re-create the Si:Al Stull Chart with a prototype Iron-Saturate glaze. In an Si:Al grid we can only adjust the amounts of Silica and Alumina, so we must set in stone the other characteristics of the glaze. Looking at the analyses of recipes in Glazy, it is apparent that we will need a good deal of Iron as well as Phosphorus. For our fluxes, apparently some MgO is required. As an educated guess, or initial prototype Iron Saturate glaze will have variable Silica and Alumina, while the following are set for all glazes: KNaO 0.2, CaO 0.6, MgO 0.2, Fe2O3 0.22, P2O5 0.12.

    We will use volumetric blending to magically create 25 glaze tests from only 4 batches of glaze. The four corner glazes composed using the Glazy Recipe Calculator. The columns originate from the Origin so that each column represents a specific Si:Al ratio. It is decided to put the “Left” column in the Stull Matte Region, while the “Right” column is pushed close to the Under-Fired Region.

    Batches of 500 grams are created for each corner glaze, and the test glazes are mixed using volumetric blending with samples of 20mg. The tests are ready to be fired!

    Note: The “educated guess” for our initial prototype glaze is informed in large part by the amazing work of Carol Marians. Carol has posted 8 years of glaze research on her website at:

    http://carol.knighten.org/

    I made a mistake on the Si:Al ratios for each biaxial column. The ratios should be approximately 4.3, 5.4, 7, 9.3, and 12.8

    Here are the results of the Iron-Saturate Biaxial. While the reduction firing with uncontrolled cooling results in brown, metallic surfaces, the oxidation firing with a controlled cool and hold at 1700°F (925°C) gives us more interesting results. The biaxial reveals that an Si:Al ratio of around 9-9.5 (the fourth column) promotes redder glazes. In particular, tile D4 (4th row, 4th column) seems promising.

    The oxidation firing schedule is adopted from Carol Marians, but simplified to:
    150°F/hr to 250°F (65°C/hr to 120°C)
    400°F/hr to 2050°F (200°C/hr to 1120°C)
    120°F/hr to 2250°F (50°C/hr to 1230°C)
    60°F/hr to 2290°F (16°C/hr to 1250°C)
    40°F/hr to 2310°F (4°C/hr to 1265°C)
    Hold of 10 minutes at 2310°F (1265°C)
    400°F to 1700°F (925°C) – Down-fire
    Hold 2 hours at 1700°F (925°C)

    See http://carol.knighten.org for many more examples of firing schedules for iron red glazes.

    From the Iron-Saturate Biaxial we choose tile D4 to work with.  We can now “zoom in” and refine the Si:Al ratio for this tile.  At Si:Al 8-8.5 the glaze seems more evenly covered in crystals.  As the Si:Al ratio is increased the coverage becomes more splotchy.

    It seems the Si:Al ratio for biaxial tile D4 was already pretty good.  Now we can move on to testing factors other than Si:Al in the prototype glaze.  In this test, we increase the level of R2O (KNaO, or K2O & Na2O) while decreasing the amount of Calcium.  I was surprised by the result for 0.3 KNaO, perhaps there would have been a better result if both Calcium and Magnesium were decreased?  Or decrease Si & Al? Anyway, based on this test I’ll just stay at R2O:RO 0.2:0.8

    Test of Iron-Saturate Biaxial tile D4 replacing Mahavir Potash Feldspar with Minspar 200 Soda Feldspar.  Not a 1-to-1 percentage replacement, but maintaining the same UMF (except K2O and Na2O).

    Now that we’ve established an R2O:RO ratio of 0.2 using Potash Feldspar, we can test the best proportion of Calcia to Magnesia.  With our R2O set at 0.2, 0.8 remains for the RO (including Calcia and Magnesia) portion of our UMF fluxes.  The educated guess of 0.6 CaO and 0.2 MgO in our original Iron Saturate biaxial turns out to be a good choice.  More than 0.2 MgO also gives some interesting glazes with a more metallic surface.

    Same UMF, different sources of Magnesia.

    Glazes are often split into two parts:  A base glaze and additives like colorants and opacifiers.  It’s like ordering a pizza (base) with toppings (additives). We’ve already tested many aspects of the Iron-Saturate base glaze including Silica:Alumina, R2O:RO, and Calcia:Magnesia.  Now we can move on to the additives: Iron and Bone Ash. (The decision between what is part of the base recipe vs. an additive is somewhat arbitrary.  Just as with a pizza that’s made it to your stomach, it all eventually ends up mixed together.) Additives are added in addition to the base glaze recipe.  So in this test, I did not alter the base glaze at all, the only difference is increasing Red Iron Oxide and Bone Ash. I was surprised to see that additional bone ash didn’t alter the glaze a lot more.

    A line blend of biaxial test D4 blended with the same recipe without Bone Ash (but maintaining the same fluxes to account for the missing CaO from the Bone Ash). Without P2O5, our glaze is a nice tenmoku.  At 0.03 P2O5 very faint traces of crystallization appear.  At 0.06 P2O5 crystallization is much more evident, and somewhere between 0.06 and 0.09 P2O5 there is a dramatic transformation.

    Testing different sources of iron using tile D4 from the Iron-Saturate Biaxial.  I’m not sure what’s going on with Yellow Iron Oxide.  It would be interesting to see other sources of iron, especially iron phosphate.

    Adding Titanium Dioxide in 1% increments to tile D4 from the Iron-Saturate Biaxial. Titanium Dioxide is often present in analyses of Song Dynasty Russet/Persimmon glazes as well as Japanese Kaki glazes, but usually in amounts of less than 1%.

  • Techniques

    Mixing plaster in a plastic bag

    I’m not a plaster master, so I don’t know if this is a good or even original idea.  By mixing plaster in a plastic bag, it seems easier to remove bubbles from the mixture, while pouring is much more controlled.  It’s the same idea as using a garden watering can for pouring glaze:  You pour from the bottom where pressure is highest and bubbles are fewest.

    Add measured amount of water, then plaster into plastic bag supported by bucket.

    Let sit for a minute or two, then stir for about 5 minutes, being careful not to entrail air into the mixture.

    Lift the bag out of the bucket, checking for leaks.

    Check for air bubbles in the mixture.

    Air bubbles trapped in the plaster mixture.

    Pat the plastic bag, vibrating the air bubbles to the top.

    Cut a small corner off the bag, and control release of plaster using fingers. Pour in a controlled fashion against a wall without splashing.

  • Glazes

    Cone 6 Oxidation Blue Triaxial Blend

    In Chinese Glazes, we learn from Nigel Woods that the cobalt used for underglaze blue & white underglazes and blue glazes came in a range of chemical compositions and grades of purity.  Thus, there are many shades of blue due to the quality of cobalt-containing stone as well the overlying glaze.

    In the same book, Nigel presents a lovely Chinese blue stoneware glaze which, in addition to cobalt, contains iron and manganese “impurities”.

    In fact I’m personally not fond at all of glazes and underglazes containing only cobalt as a coloring oxide.  Pure cobalt often comes out as a garishly blue color.  In the triaxial blend below, I take a nice clear glaze (Sue’s Clear) with added 1% Cobalt Carbonate.  Then I blend with 1.5% Red Iron Oxide (bottom left) and 1.5% Manganese Dioxide (bottom right).  The resulting colors on the bottom row are much more pleasing to my eye.

    The full image can be viewed here:  http://www.derekau.net/wp-content/uploads/2014/12/BLUE_TRIAX_ALL.jpg

  • Glazes

    Orton Cone 6 Clear Glazes

    Having not fired cone 6 since college, I started by first testing a number of clear cone 6 glazes on https://glazy.org

    I also studied up on cone 6 glaze chemistry via Matthew Katz​’s Advancing Glazes course and his papers: Boron in GlazesMid-Temperature Glaze ScienceGlaze Safety/Durable Glazes Presentation.

    Click here for full image of cone 6 clears.

    Out of these tests, there were two glazes that I preferred.  The first, Sue McLeod​’s Clear, is a soft clear with minimal clouding and has B2O3 at 0.18 which, according to Matt’s information, is ideal for cone 6 glazes.

    The second glaze is a shop glaze available at the Wellsville Creative Arts Center called WCAC Celadon Clear.  With B2O3 at 0.45, it is really high in boron and possibly less durable than the lower-boron clears I tested.  However, WCAC Celadon Clear is by far the clearest glaze I’ve tested, almost like a layer of pure glass or honey.  Even on dark stoneware it’s really clear with almost no clouding.

     

    Sue's Clear on cone 6 porcelain

    Sue's Clear on cone 6 Brooklyn Red

    WCAC Celadon Clear on cone 6 porcelain

    WCAC Celadon Clear on cone 6 Brooklyn Red

    Being new to cone 6, I was curious as to the effect of boron levels on clear glazes.  So, I created two biaxials, both with R2O fixed at 0.2.  In the first Sue’s Clear inspired biaxial, B2O3 is set at 0.18.  In the second biaxial inspired by Celadon Clear, B2O3 is doubled to 0.36.

    Each biaxial resulted in a nice clear, with the higher Boron clear being almost completely transparent and glossy, while the Boron 0.18 clear is translucent and soft.

    Standard Cone 6 Porcelain Body #551

    Link to full-size image here.

    Same chart but with words describing each test glaze:

    Best Clear at B2O3 0.18

    The best clear resulting from the B2O3 0.18 biaxial is here: C6 R2O 0.2 B2O3 0.18 Best Clear

    B2O3 0.36 Biaxial

    In order to test the effect of higher B2O3 levels, I doubled the amount of Boron in the initial biaxial from 0.18 to 0.36 while maintaining the same R2O:RO ratio.  I also made the boundaries of the tests a little higher (see map comparison).  I was surprised to see that the only clear glazes in the 0.36 Boron test appear much farther down (lower in Si & Al) in the chart.  But the “clear” region is still in the same Si:Al Stull region.

    Link to full size image here.

    Best Clear at B2O3 0.36

    The best clear resulting from the B2O3 0.36 biaxial is here: C6 R2O 0.2 B2O3 0.36 Best Clear

    It is similar to WCAC Celadon Clear in it’s glossy, transparent quality.

    High-Boron Clears

    After testing WCAC Celadon Clear and seeing the results of my B2O3 0.36 biaxial, it seems there is definitely a region of very glossy, very clear glazes at higher boron levels.

    Coincidentally, I tested an old glaze recipe posted to the Clayart mailing list by Laura Speirs in 1996:  https://glazy.org/recipes/21102  As with the WCAC Celadon Clear, the Speirs recipe is also very high in Boron (0.51), and it also fires very clear and glossy:

     

    VC Easy Glossy

    One afternoon I began discussing the WCAC Celadon Clear with a WCAC member, Nancy Alt.  I was very surprised to discover the interesting history of this glaze.

    In 2009 Nancy Alt had visited Val Cushing’s home and purchased a vase with a lovely blue-green celadon glaze. Nancy asked Val if he could share the glaze recipe, and he not only shared it but converted it from cone 9 to cone 6 (the temperature Nancy was firing). Val’s email is copied below. It shows the extremely generous nature of this amazing potter and teacher:

    From: Val Cushing

    Subject: Re: celedon glaze

    Date: May 12, 2009 at 12:46:57 PM EDT

    To: Nancy Alt

    Dear Nancy,

    This glaze is one I made for C/9 oxidation electric firing, so that it would appear to be a blue green celadon. I have revised it for you to be the same color and texture only for C/6 ox. electric . I will give you two to try , first VC Pale Emerald, C/6 , glossy , blue/green , celadon looking. as follows………. Kona F/4 feldspar 24, Ferro Frit 3134 24, Dolomite 4, whiting 14, barium carbonate 2, zinc oxide 2, flint 24, and EPK 6. ADD TO THAT , 1/2 % COPPER CARBONATE for blue green. VC/easy glossy, C/6 ox. , electric , celadon looking , green. Cornwall Stone 46, Gerstley Borate 20, Ferro Frit 3124 26, Ball Clay 8. — add 2% copper carb. and 1/2 % red iron oxide for celadon looking green color. Test these two Nancy and if the color is not exactly what you expected let me know and we can make a revision. We may have different “tastes” about color , but we can get what you want…My pale emerald should be quite a bit like the glaze on the jar of mine you now have. and THANK YOU . Val

    So it turns out that the glaze I liked so much, WCAC Celadon Clear, was actually a Val Cushing recipe called “Easy Glossy”.  I checked Cushing’s Handbook for the recipe and didn’t find it.  Nor could I find similar recipes in the Glazy database.  So it’s quite possible this is a newly discovered Val Cushing glaze recipe.

    However, the WCAC Celadon Clear had been modified from the original “Easy Glossy”, most notably subbing Gerstley Borate for Gillespie Borate.  I wanted to see not only the original recipe but also the color variations that Cushing was working with.  So I created a triaxial blend.

    Below is the triaxial blend using Copper Carbonate and Red Iron Oxide.

    Click here for Val Cushing’s “Easy Glossy” on Glazy.org

    Click here to download full size image.

    From Safety & Durable Glazes Presentation

    From Boron in Glazes

  • Photos

    Smartphone Macro Photography

    I’ve tried a number of smartphone lenses in the article Smartphone Microscopy.

    Today I received my first macro lens for smartphones, the Xenvo iPhone Camera Lens Kit Pro – Macro Lens & Wide Angle Lens with LED Light.

    The lens was a bit expensive ($35), but opening the package I was surprised at the weight and feel of quality materials and real glass.  I’ve only taken a few photos so far but the image quality seems pretty good.

    Xenvo iPhone Camera Lens Kit Pro with LED Light

    Macro Lens & Wide Angle Lens attached to iPhone 7

    Macro Lens attached to iPhone 7

    I’m still not sure how I’ll incorporate macro photos of glazes into my documentation.  So far I’m pretty happy with how the macro photos reveal glaze details not visible in normal photos, but still show the character of the glaze (as opposed to microscopic images).

    Here are some images of Katz-Burke Matte with 5% Rutile 5% Mason 6600.

    Normal photo taken with iPhone 7.

    Macro photo taken with iPhone 7 & Xenvo lens.

    Here are some images of WCAC Clear Celadon:

    Normal photo taken with iPhone 7.

    Macro photo taken with iPhone 7 & Xenvo lens.

    Just to test, here is an example from the Xenvo Wide Angle Lens.  It’s a bit blurry on the edges.

    Original photo from wide angle lens.

    Same photo corrected for lens distortion.

  • Uncategorized

    Clear Cone 6 Oxidation Glazes

    Link to full size cone 6 clear glaze comparison image here.

    Recently I joined a community studio that only fires cone 6 oxidation.  Last time I fired cone 6 I was in college!  So I am learning about cone 6 glazes from various resources:

    Boron in Glazes by Matt Katz

    Mid-Temperature Glaze Science by Matt Katz

    Understanding Cone 6 by Sue McLeod

    These clear oxidation cone 6 glaze recipes all came from Glazy:

    Clear, cone 6 glaze images by Derek

    My personal favorite is Sue McLeod’s clear, followed by the WCAC Celadon Clear.  However, the Celadon Clear is high in boron and may have issues with durability?  The Digitalfire “G” glazes are also quite nice.  Campana clear is very clear on porcelain but peforms badly on the stoneware.

  • Uncategorized

    Clay Akar Yunomi 2018

    Special thanks to those of you who supported ceramic artists in the Clay Akar Yunomi 2018 Show!  I feel very lucky to have my five cups sold.  There are still lots of great cups for sale:  https://www.clayakar.com/pages/yunomi-creators-2018

  • Work

    Jun Variation #2

    Another variation of the Jun glaze, with 2% Bone Ash and 1% Iron oxide.

  • Tests

    Tichane’s Tests

    Some of Robert Tichane’s glaze tests and reproductions of Chinese Glazes donated to the Freer and Sackler Galleries: https://archive.asia.si.edu/collections/edan/default.cfm?searchTerm=tichane&btnG.x=0&btnG.y=0&btnG=Search

    Glaze sample: Jun with copper red; Small bowl with two copper-red spots on outside, two on inside

    Modern reproduction of Yaozhou ware bowl from original mould in Metropolitan Museum of Art

  • Work

    Waxy

  • Work

    Last-minute

  • Craft

    72 Hands

    From the Tiangong Kaiwu (天工開物) encyclopedia compiled by Song Yingxing (宋应星) at the end of the Ming Dynasty comes the oft-cited quote:

    “共计一杯工力,过手七十二,方可成器”

    For the total work required to make a single cup, it must pass through 72 hands, and only then can it become a vessel.

    72 Hands is an effort to document all types of ceramics techniques.  The video style is very simple- a single take of each technique focusing on the artisan’s hands.  Each video is accompanied by an article with a description of the technique and photos.  Videos are shot in high-resolution 4K Ultra-HD resolution which gives a clear view of the technique.

    Support 72 Hands

    To support the continuation of this documentary series, please consider becoming a patron.

  • Work

    From, In, to Jingdezhen

    “From, In, to Jingdezhen; Eight Experiences”, an exhibition organized by Jae Won Lee, brought together a mix of artists who make work in Jingdezhen.

    For this exhibition I refined the porcelain slipware that I began last year, exploring new designs with brushed slip.  I also began a documentary project, 72 Hands (72hands.org), in which I am recording traditional craft techniques in high-definition video.

    Gimhae Clayarch Museum Exhibition Page

  • Work

    Lobed dishes

    A series of lobed dishes inspired by Song dynasty lacquerware.

  • Photos

    Ticking away