Cone 10 Engobe for H550
Recipe
Notes
Both Zircopax and Black Stain are shown as additions. Use one or the other (to get white or black). This recipe the product of a series of tests where the percentage of nepheline syenite was progressively reduced (from 25% originally) to reduce the firing shrinkage to match H550 (it is important that engobes shrink the same as the body or they will flake or crack off during firing or later during ware use). Amazingly only 10% nepheline syenite is needed to make this fit Plainsman H450, H550. Again, do not use this recipe on porcelains (e.g. P700) or whitewares (e.g. H570, P600), the recipe needs more nepheline for them (to increase firing shrinkage, we have another recipe, L3954J that does this). This creates very plastic slurry so it sticks well to leather hard clay (because of the high percentage of ball clay). If you do not have this brand name of ball clay then substitute another. The Zircopax version fires quite white, leave it out completely if that is too white. If on thick enough this will block and body speckling, glazes will react as if on porcelain. As an engobe this works best when mixed as a thixotropic slurry. Please follow the instructions for the cone 6 version at the L3954B page at the Plainsman Clays website.
Description
White