A Low Cost Tester of Glaze Melt FluidityA One-speed Lab or Studio Slurry MixerA Textbook Cone 6 Matte Glaze With ProblemsAdjusting Glaze Expansion by Calculation to Solve ShiveringAlberta Slip, 20 Years of Substitution for Albany SlipAn Overview of Ceramic StainsAre You in Control of Your Production Process?Are Your Glazes Food Safe or are They Leachable?Attack on Glass: Corrosion Attack MechanismsBall Milling Glazes, Bodies, EngobesBinders for Ceramic BodiesBringing Out the Big Guns in Craze Control: MgO (G1215U)Ceramic Glazes TodayCeramic Material NomenclatureCeramic Tile Clay Body FormulationChanging Our View of GlazesChemistry vs. Matrix Blending to Create Glazes from Native MaterialsConcentrate on One Good GlazeCone 6 Floating Blue Glaze RecipeCopper Red GlazesCrazing and Bacteria: Is There a Hazard?Crazing in Stoneware Glazes: Treating the Causes, Not the SymptomsCreating a Non-Glaze Ceramic Slip or EngobeCreating Your Own Budget GlazeCrystal Glazes: Understanding the Process and MaterialsDeflocculants: A Detailed OverviewDemonstrating Glaze Fit Issues to StudentsDiagnosing a Casting Problem at a Sanitaryware PlantDrying Ceramics Without CracksDuplicating Albany SlipDuplicating AP Green FireclayElectric Hobby Kilns: What You Need to KnowFighting the Glaze DragonFiring Clay Test BarsFiring: What Happens to Ceramic Ware in a Firing KilnFirst You See It Then You Don't: Raku Glaze StabilityFixing a glaze that does not stay in suspensionFormulating a body using clays native to your areaFormulating a Clear Glaze Compatible with Chrome-Tin StainsFormulating a PorcelainFormulating Ash and Native-Material GlazesG1214M Cone 5-7 20x5 Glossy Base GlazeG1214W Cone 6 Transparent Base GlazeG1214Z Cone 6 Matte Base GlazeG1916M Cone 06-04 Base GlazeG1947U/G2571A Cone 10/10R Base Matte/Glossy GlazesGetting the Glaze Color You Want: Working With StainsGlaze and Body Pigments and Stains in the Ceramic Tile IndustryGlaze Chemistry Basics - Formula, Analysis, Mole%, Unity, LOIGlaze chemistry using a frit of approximate analysisGlaze Recipes: Formulate Your Own InsteadGlaze Types, Formulation and Application in the Tile IndustryHaving Your Glaze Tested for Toxic Metal ReleaseHigh Gloss GlazesHow a Material Chemical Analysis is DoneHow desktop INSIGHT Deals With Unity, LOI and Formula WeightHow to Find and Test Your Own Native ClaysHow to Liner-Glaze a MugI've Always Done It This Way!Inkjet Decoration of Ceramic TilesIs Your Fired Ware Safe?Leaching Cone 6 Glaze Case StudyLimit Formulas and Target FormulasLow Budget Testing of the Raw and Fired Properties of a GlazeLow Fire White Talc Casting Body RecipeMake Your Own Ball Mill StandMaking Glaze Testing ConesMonoporosa or Single Fired Wall TilesOrganic Matter in Clays: Detailed OverviewOutdoor Weather Resistant CeramicsOverview of Paper ClayPainting Glazes Rather Than Dipping or SprayingParticle Size Distribution of Ceramic PowdersPorcelain Tile, Vitrified or Granito TileRationalizing Conflicting Opinions About PlasticityRavenscrag Slip is BornRecylcing Scrap ClayReducing the Firing Temperature of a Glaze From Cone 10 to 6Simple Physical Testing of ClaysSingle Fire GlazingSoluble Salts in Minerals: Detailed OverviewSome Keys to Dealing With Firing CracksStoneware Casting Body RecipesSubstituting Cornwall StoneSuper-Refined Terra SigillataThe Chemistry, Physics and Manufacturing of Glaze FritsThe Effect of Glaze Fit on Fired Ware StrengthThe Four Levels on Which to View Ceramic GlazesThe Majolica Earthenware ProcessThe Potter's PrayerThe Right Chemistry for a Cone 6 MgO MatteThe Trials of Being the Only Technical Person in the ClubThe Whining Stops Here: A Realistic Look at Clay BodiesThose Unlabelled Bags and BucketsTiles and Mosaics for PottersToxicity of Firebricks Used in OvensTrafficking in Glaze RecipesUnderstanding Ceramic MaterialsUnderstanding Ceramic OxidesUnderstanding Glaze Slurry PropertiesUnderstanding the Deflocculation Process in Slip CastingUnderstanding the Terra Cotta Slip Casting Recipes In North AmericaUnderstanding Thermal Expansion in Ceramic GlazesUnwanted Crystallization in a Cone 6 GlazeVolcanic AshWhat Determines a Glaze's Firing Temperature?What is a Mole, Checking Out the MoleWhat is the Glaze Dragon?Where do I start in understanding glazes?Why Textbook Glazes Are So Difficult
Painting Glazes Rather Than Dipping or Spraying
Potters who are used to dipping and spraying glazes might be surprised to learn how well glazes can paint on if they have enough gum in the recipe.
Likely you have had problems getting glazes to apply evenly when dipping ware. Many dipping glazes either dry too fast or too slow, drip or curtain during draining, settle out quickly, crack during drying or go on too thick or thin. In industry 'lay-down' is considered a big factor in the ability to fire a piece with an even glaze layer free of defects. On small or delicate ware it can be very difficult to achieve good laydown.
If you have ever used commercial glazes from Duncan or Mayco you know that although the idea of painting glaze onto ware can be quite strange to potters, it actually works very well. It is just about impossible to evenly paint a typical dipping glaze, they dry way too fast and just don't flow like paint. So how does Duncan or Spectrum make a glaze 'paintable'. The answer is gum. Lots of gum.
CMC gum, for example is an organic sodium carboxymethylcellulose (like a glue) that is normally employed to harden unfired ceramic glazes (cement the particles together) for safer handling of the ware. Although CMC gum is not intended as a suspending agent, amazingly it can do exactly that. You can actually make fritted glazes that contain almost zero clay content and suspend and harden them totally using gum.
A very nice side effect of the addition of gum is that glazes dry slower. In fact, you can tune the amount of gum in the mix to achieve the drying speed you want. It should paint and flow nicely but dry fairly quickly after laydown.
How much should you use and how do you put gum in a glaze? Powdered gum resists dispersion in water thus it is difficult to add it to an existing liquid batch. However if gum powder is mixed with other dry ingredients before adding them to the water it can be done (often 0.5-1.5%). A much more effective method is to boil water, add about 25-30 grams of powdered gum per litre and mix vigorously with a mechanical mixer. Normally this mixture is added during mixing to replace part of the water however I have found that for brushing it should be used to makeup the entire water complement. There is room to use 40 grams per liter if needed.
Amazingly, even though the gum solution is quite thick and syrupy, added powder mixes in very easily. The gum solution seems to wet the particle surfaces better than water alone.
Each glaze will paint a little differently. If you find that a glaze dries too quickly and does not flow enough try adding a little more water before deciding that the gum content is too low.
Consider some of the advantages of painting glazes:
- If you make small pieces you can make small batches of glaze and even store them in glass containers (i.e. large baby food jars). Thus you can have a lot more glazes at your disposal.
- You don't need to bisque fire. Glaze paints onto greenware just fine, you just have to be careful when handling the ware if it is thin.
- You can apply very thin layers and apply multiple layers of different types of glaze for visual or decorative effects.
- You can make specialized glazes of very low clay content or you can use lower iron and less plastic kaolins (as opposed to dirtier ball clays) to make cleaner and whiter glaze surfaces.
Since CMC is an organic material there can be problems with microbial growth in your glazes. If this occurs, you can use a small amount of Dettol® (from the Pharmacy, actice substance chloroxylenol).