Measuring Viscosity

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What is Viscosity?

Measuring Viscosity

Measuring Viscosity: The 60 cc veterinarian's syringe is an effective tool for measuring this property. Just pull out the needle and time how long it takes the slip to run out from the 60 cc mark to the 10 cc mark. Calibrate the test on a sample of slip that performs well. If the syringe's hole is less than 2-3 mm, this slip will run out too slow. If that is the case, use the viscometer that comes with the Lehman Slip Test Kit. Thus, for any given viscosity there can be a whole range of possible specific gravities, and for a given specific gravity a slip can have many different viscosities depending on the state of deflocculation. The most common method of preparation is to achieve the specific gravity first using the needed deflocculant, then fine-tune the viscosity using a little more of the same deflocculant. Normally, beginners should try to achieve a specific gravity of 1.75, while experts will be able to work comfortably at 1.8 for most body types.
Various typical recipes for standard low-temperature whiteware and porcelain slips call for quite different amounts of water. This underscores the importance of being able to measure specific gravity and viscosity. Below, I have provided some guidelines on mixing a slip. Keep in mind that slip mixing is actually a three-phase project. The first few times must be dedicated to creating a workable recipe and technique. After this, a period of fine tuning will perfect a process that can be committed to paper for repeating on a routine basis. The notes to follow thus refer to the early stages of learning to mix a particular slip recipe.

   

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