To calculate solid content, you determine the percentage of material that remains after the liquid (typically water or solvent) has been removed from a sample. This is done by comparing the weight of the dry sample to the weight of the original wet sample.
The fundamental formula for calculating solid content, often expressed as a percentage, is:
% Solids = (Net weight of the dry specimen / Net weight of the original specimen) x 100
Based on the provided reference, this formula can be broken down using specific weight measurements:
Where:
- A = Tare weight of the dish (the empty container used to hold the sample).
- B = Weight of the dish plus the original specimen (wet sample).
- C = Tare weight of the dish plus the weight of the dry specimen (after drying).
The net weight of the original specimen is (B - A).
The net weight of the dry specimen is (C - A).
Therefore, the formula becomes:
% Solids = { (C - A) / (B - A) } x 100
(Reference source dated 30-Sept-2011 provides this formula)
Understanding the Solid Content Calculation
Solid content is a critical measurement in many industries, including manufacturing, coatings, food production, and environmental testing. It tells you what percentage of your product or material is actual solid matter, excluding any solvents or volatile components that evaporate during drying.
Key Steps to Calculate Solid Content
Follow these steps to determine the solid content of a sample:
- Weigh the Empty Dish (Tare Weight): Place the clean, dry dish or container on a scale and record its weight. This is A.
- Add the Wet Specimen: Place a known amount of the wet sample into the dish and weigh the dish plus the sample. Record this combined weight as B.
- Dry the Specimen: Place the dish with the wet sample in an oven or other appropriate drying apparatus at a specified temperature and time until all the liquid has evaporated and the sample is completely dry. The drying method (temperature, time, vacuum) should be consistent and appropriate for the material being tested.
- Weigh the Dry Specimen: Remove the dish with the dry sample from the drying apparatus, allow it to cool (if necessary, to avoid thermal effects on weighing), and weigh the dish plus the dry sample. Record this combined weight as C.
- Calculate Solid Content: Use the formula with the recorded weights A, B, and C.
Example Calculation
Let's illustrate with a practical example:
Suppose you are testing a paint sample.
- Empty dish weight (A) = 25.0 grams
- Dish + wet paint weight (B) = 75.0 grams
- Dish + dry paint weight (C) = 45.0 grams
Now, apply the formula:
% Solids = { (C - A) / (B - A) } x 100
% Solids = { (45.0 g - 25.0 g) / (75.0 g - 25.0 g) } x 100
% Solids = { 20.0 g / 50.0 g } x 100
% Solids = 0.40 x 100
% Solids = 40%
This means that 40% of the original paint sample was solid material, and the remaining 60% was liquid (like water or solvent) that evaporated during drying.
Tabular Summary of Weights
| Measurement | Symbol | Description | Example Value |
|---|---|---|---|
| Tare Weight of Dish | A | Weight of the empty container | 25.0 g |
| Dish + Original Specimen | B | Weight of the container plus the wet sample | 75.0 g |
| Dish + Dry Specimen | C | Weight of the container plus the dry sample | 45.0 g |
| Net Weight of Original Specimen | B - A | Weight of the wet sample only | 50.0 g |
| Net Weight of Dry Specimen | C - A | Weight of the dry sample only | 20.0 g |
Calculating solid content is a fundamental analytical technique providing essential information about material composition and concentration.
