The simplest way to lower the specific gravity of a glaze is to add water and mix it thoroughly. This reduces the density of the glaze.
Understanding Specific Gravity in Glazes
Specific gravity, in the context of pottery glazes, refers to the density of the glaze mixture compared to the density of water. A glaze that's too thick may have too high a specific gravity. Conversely, a glaze that's too thin has too low a specific gravity. Adjusting the specific gravity is crucial for achieving a good, even coat when applying the glaze to your ceramic piece.
Methods to Decrease Specific Gravity
As mentioned in the provided reference, there's a direct and effective method to reduce the specific gravity of your glaze mixture:
- Adding Water:
- The primary way to decrease a glaze's specific gravity is to add water gradually while mixing.
- This process dilutes the concentration of solids in the glaze and lowers the overall density.
- Be careful to add water in small increments, and mix thoroughly after each addition. This helps you avoid making the glaze too thin too quickly.
Practical Tips and Example
Here’s a step-by-step method to follow:
- Initial Measurement: Start by measuring your glaze's specific gravity using a hydrometer or by using the "two leaders, mark, and weigh" technique as the source implies. This gives you a baseline.
- Add Water Gradually: Begin adding small amounts of water to your glaze, such as 5-10 ml at a time if working with smaller batches.
- Mix Thoroughly: After each addition of water, mix the glaze very well. This ensures the water is uniformly dispersed and not pooling in one spot.
- Re-measure: After each mixing, check the specific gravity again.
- Repeat: Continue adding water in small increments and measuring until you reach your target specific gravity.
Key Considerations
- Consistency is Key: Maintaining a consistent specific gravity helps ensure consistent results from glaze application.
- Record Your Adjustments: Always keep a log of adjustments you make. This way you can replicate your adjustments in future batches.
- Trial and Error: Be prepared to do some testing to find the precise specific gravity that works for your particular glaze and application method.
