About This Tool
This application is a digital lab notebook designed for potters and ceramic technicians. It calculates Specific Gravity (SG), which is crucial for glaze consistency. By weighing a fixed volume of liquid (using a Density Cup) or using a Hydrometer, you can ensure your glaze is exactly the same thickness every time you fire.
The Density Cup
Also known as a specific gravity cup or pycnometer. It is a precision instrument, usually stainless steel, with a hole in the lid to allow excess liquid to escape, ensuring an exact volume (typically 100ml or 100cc).
How to use: Weigh empty cup. Fill with glaze. Cap it. Wipe clean. Weigh full cup. Enter data into the calculator.
Baumé Hydrometer
A glass float used to measure the density of liquids. In ceramics, we often use the Baumé scale (°Bé).
While easier to use than a cup (just float it in the bucket), it can be less accurate if the glaze is thick (thixotropic). Use the "Unit Kitchen" in this app to convert Baume readings to Specific Gravity.
Pint Weight Management
Historically, specifically in the UK and US ceramic industries, potters didn't always have decimal scales. They used "Pint Weight."
They would take a standard pint jar (approx 473ml in US, 568ml in UK - this app uses US Pint standard for conversion), weigh the liquid, and record that weight.
Example: "This glaze needs to be 24oz per pint."
The app converts this historical measurement back into Specific Gravity (SG) so you can communicate with modern scientific standards.
Calculate Water Addition
The Glaze Dilution Fixer in the "Lab Tools" section helps you thin down a glaze that is too thick.
- Current SG: Enter the result from your density test (e.g., 1.65).
- Target SG: Enter what you want it to be (e.g., 1.50).
- Total Vol (ml): Estimate how much glaze you have in the bucket (e.g., 5000ml).
The result will tell you exactly how many milliliters of water to add to reach your target thickness.
Starting Standard Measurements
| Material Type | Specific Gravity (SG) | Notes |
|---|
| Water | 1.00 | The baseline. |
| Clear / Gloss Glaze | 1.45 - 1.50 | Thinner for dipping biscuits. |
| Matte / Opaque Glaze | 1.50 - 1.60 | Often needs to be thicker to cover. |
| Spraying Glaze | 1.60+ | Variable, but usually less water. |
| Casting Slip | 1.72 - 1.78 | Very heavy liquid clay. |