Slipmaking 101 or how to make low fire ceramic slip.



Soda Ash and Sodium Silicate are DEFLOCCULANTS. They make the particles of clay all repulse each other (like two north poles on a magnet). Proper deflocculation allows the use of less water to make the slip a liquid, this keeps the molds from getting too wet.

CLAY: The 1-4 and Kaolin are clays, they are the actual clay in the formula.

This is for a ceramic slip, compatible with all Duncan, Amaco & Mayco low fire glazes. Bisque is cone 04, Most glaze fire to cone 06.

We sell it premixed in 1 gallon bottle, ups shipment only.

White Slip Recipe (cone 04)

The first time you make slip it all seems mysterious; it is especially important that you measure carefully and keep a written record of what you have done. There are seasonal variations in the ingredients; so, it is important to know what you have done in the past and be consistent. First figure out how many gallons your slip mixer will hold. It is easiest to make 25 or 50 gallons as you will not have to weigh the slip components. Test slip with a hydrometer, or scale, it should read 1.75, and weigh 14.5 lb. per gallon.

1.  WATER ----- 27 GALLONS the warmer the better.

2.  SODA ASH -----4 OZ. DRY

3.  Dissolve Soda in hot water and add to water and allow to stir with mixer running add your Clay.

4.  KT 1-4 Ball Clay----- 250 LBS. 5 BAGS

5.  Dolomite ----- 50 LBS. 1 Bag.

                       When the mix seems too thick start adding the Sodium Silicate a little at a time


7. Hydrated Magnesium Silicate ----- 200 Lb.

    Let the mixture mix for as long as possible and then rest overnight.


   1.   WATER ----- 27 GALLONS the warmer the better.

2.  SODA ASH -----4 OZ. DRY

3.  BARIUM CARBONATE ____4 Oz. Dry

         Dissolve Soda and Barium in hot water and add to water and allow to stir with mixer running add your Clay.

4.  REDART CLAY  --- 400 LBS. 8 BAGS


When the mix seems too thick start adding the Sodium Silicate a little at a time

6.  Hydrated Magnesium Silicate ----- 100 LBS. 2 BAGS add the Dolomite with the mixer running. If it clogs up at the top, Turn the mixer off and use a stick to help mix it in.

7.  Let the mixture mix for as long as possible and then rest overnight.



  • Barium prevents white scumming on the bisque.
  • Hydrated Magnesium Silicate functions to prevent the glazes from crazing and to make the bisque white. 

Testing your slip


















 There are two properties of slip that we want to test frequently. They are specific gravity and viscosity. Specific gravity means how much more than water does the slip weigh. For instance: A gallon of water at 70 degrees weighs 8.3 lb. Lets say we weight out a gallon of slip and it weighs 14.4 lb. Simply divide 14.4/8.3= 1.73.This is a ratio, it is generally accepted that 1.75 is good for slip casting. So our slip is a little light at 14.4 lb. per gallon, water weighs less than clay so we have too much water in our slip, we can’t take it out so we have to add more dry materials. (if the slip was too heavy we could have added water.) Okay, now we weigh the slip again and it is 14.5 pounds plus a little. Do the math and you can tell that you are right at 1.75.

 Unfortunately 1/10 of a pound is not as accurate as we would like so we use grams (1/10 lb. = 45.4 grams)

            The Viscosity refers to how thick a liquid is. With slip we like to change how thick it is by adding more deflocculant (Sodium Silicate) NOT by adding water.

            How thin do you want the slip to be? It depends on what you are making.  Hollow beads or tiny miniatures require thin slip, large items require thicker slip.

Measure viscosity by how long it takes (in seconds) to drain out of a container with a small exit hole. The best thing to do is find some slip you like, then time it using a viscosity meter how long it takes until the flow changes from constant to drips..

Each time you do this test try to do it exactly the same way.


If the slip is too thick and the specific gravity is right, then you can add some deflocculant, or some special slip thinner. These are very powerful in their action add only 2-3 drops per gallon.

           Other Qualities.

  • Absorption: How porous the bisque is determines how easy the glaze is to apply, it changes by what cone the slip is fired to, and the composition of the slip.
  • Thermal expansion: Determines glaze fit, a too tight fit and the glaze falls off (shivering ), too loose and the glaze crackles (crazing). Glaze fit is determined by the amount of talc in the slip and the bisque temp.
  • Shrinkage: Is complicated to control, but it is useful to know so that you know how to size the molds, more water in the slip gives increased shrinkage and increases cracking in the mold.
  • Over deflocculation: Slip casts slow, inside of cast appears sharp and greenware is brittle, hard. Noses and other high points may turn brown when dry.
  • Under Deflocculation: Slip casts fast, seems soft and flabby, molds get wet sooner. inside of casts look smooth.

this from Duncan 1982......


The first requirement for making a good casting slip is the realization that it cannot be done by any hard-and-fast rule. Many factors enter into the making of a good slip, any one of which will change its quality and working properties. The main factor is the purity of the water, but many other factors will have their effect. 


1. For each 100-pound batch of clay, pour five (5) gallons of clean water into the mixing barrel or container.

2. Draw off one (1) pint of this water into a separate container and add one ( 1) 01;1nce dry soda ash to it. Mix thoroughly.

3. To the soda ash-water mixture, add one-quarter (1/4) cup of sodium silicate ('N' Brand) and mix well. (Other brands may vary in performance.)

4. Pour the mixture into the mixing barrel.

5. Gradually add 100 pounds of dry clay to the water mixture, stirring constantly to allow proper dispersion. If mixture becomes too thick to be stirred easily, an additional 1/4 cup of sodium silicate can be added A FEW DROPS AT A TIME. Resume adding remainder of dry clay, mixing thoroughly to prevent lumps of undissolved clay powder.

6. Draw off exactly one quart (32 fl. oz.) and weigh on a scale. (A diet scale which shows ounces and grams is excellent for this purpose.) This quart should weigh approximately 56 oz. net. If it is heavier than 56 oz. net, add small amounts of water to the entire clay mixture and draw off a new sample for weighing. Repeat if necessary. If the quart weight is between 50 and 56 oz., allow some of the water to evaporate to increase the weight. If the weight is less than 50 oz., solids can be added back, however, this is very difficult and tricky to control. Care and accuracy in mixing is the best assurance of proper slip.

7.     Allow the slip mixture to set overnight before using, to permit proper aging.

8.     As a safety factor, strain slip as it is poured into containers which will be used for casting. This will remove any foreign materials which may have fallen into the mixing barrel as well as catching any small lumps of clay.


1.  Short, crumbly or brittle greenware -caused by too much sodium silicate in the slip mixture.

2. High shrinkage or cracking in mold -too much water in the slip.

3.      Gummy ware after the normal set-up time-too much soda ash or too little sodium silicate in the slip.

4.      Clay settles to the bottom of slip container, leaving a large waterhead; (sometimes floating black particles are visible on the surface) -can be caused either by too much sodium silicate and/or too much water in the slip. 

5.      Thick slip after normal aging period -high evaporation of water.


  • Ermine White Stoneware with speckles

    $0.68 Per Pound As low as: $0.44 Per Pound

    Ermine - White Stoneware w specks Cone 6

    Ermine Is a midrange white stoneware with  fine speckles that bleed into the glaze imitating cone 10 gas reduction looks.
    An excellent plastic throwing body.
    Works with most glazes, testing is recommended with Amaco PC9,10,11 

    A great beginners clay as it is very forgiving and easy to throw. Most glazes look bright and colorful on this white clay. This body resists crazing and can be used for small outdoor tile.
    Also available Especkled.

  • Mayco SW219-P Opal Lustre ^6 Pint

    Regular Price: $17.00

    Sale Price $14.45

    MCSW219-P Opal Lustre ^6 Pint
    What are Micros? Micro's are short for microcrystalline which is a glaze that develops small crystallization from the the zinc and silica during the cooling process. Micros do not actually contain a glass crystal like our other stoneware crystal glazes, Rather, the effect is created by the glaze itself during the firing process. These glazes can be fired from cones 5-10, but the crystallization may not form at higher temperatures. The micros are not dinnerware safe due to surface durability. We recommend using micros on the outside of dinnerware, below the lip line or on decorative wares.

    Cone 6 oxidation (larger image): Opal Lustre is a glossy, semi-opaque glaze that displays variegated shades of blues, greens, and purples. Breaks warm brown over texture.

    Cone 10 reduction (smaller image): Color flattens, and warm undertones come through.

    TIP: This glaze is semi-fluid at 3 coats. Additional coats or increased application thickness may result in movement. Can be used in oxidation or reduction firings. Results may vary. The choice of clay body, thickness of application, firing process, and temperature will greatly affect the fired results. Always test your application on your clay body in your kiln environment. 

  • China Paint Set


    Concentrated Color Ceramic Overglaze Paints

    On a previously fired glaze surface paint as you would watercolors.

    Clean up with water. Fire to cone 017 1400F

    Includes 4 strips of 6-colors 

    Concentrated on-glaze color pigments, firing temperature 750-850 degrees C

    No grinding required, just apply with a brush or pen

    Open the cover to use, can be used for DIY ceramic painting.

    Most China 

  • WLO-W WHITE EARTHENWARE (04) with slight texture

    $0.74 Per Pound As low as: $0.49 Per Pound

    WLO-W White Low fire  clay With slight texture (04) 25 lbs.

    Sold in 25lb increments. Is a smooth white clay with added fireclay and temper. 

    The clay is smooth, softer and because it has a little texture easier to work with . It looks like porcelain in the bag and after throwing it has just a hint of texture.

    It is our most popular clay with schools and teachers because it is very soft and easy to use. It is excellent for all types of modeling projects and compatible with all MAYCO glazes.

                                           FIRE TO CONE 04 BISQUE, O6 GLAZE FOR BEST RESULTS.

    Now with Hydrated Magnesium Silicate !