One thing to keep in mind when measuring creams, gels, pastes, and other semi-solid materials is to maintain a consistent sample thickness. One option is to “sandwich” a fixed quanity of your semi-solid material in a suitable clear-bottomed container, so that it can be placed at the port for measurement.
A clear plastic dish with good optical characteristics can be used for this purpose. Just choose the appropriate diameter to completely cover the port and an appropriate height to make the sample effectively opaque.
To prepare the sample:
- Place the bottom half of the dish onto a scale and tare it to zero.
- You will need to empirically determine the appropriate sample weight that will allow the material to consistently fill the container to full when pressed closed.
- Pour a fixed quanity of the material such that it mounds up in the middle.
- Press the top half of the dish onto the bottom half so that the material squishes into the edges and presents a flat uniform surface across the entire bottom of the dish.
- Center the dish at the port and measure.