Weight per Gallon Cups are used to quickly and accurately determine the weight per gallon, and also the specific gravity of paints, lacquer, pastes, semi-pastes, and other liquid or semi-liquid materials.

Until the middle of 1989, GARDCO weight per gallon cups were fabricated using Series 300 Stainless Steel for the sidewall and the easier machined but less corrosion resistant Series 400 Stainless Steel for the base and cover. Now, with the installation of state-of-the-art computer controlled metal cutting machinery, these cups are machined from Series 300 Stainless Steel solid bar stock.

1. Determine the weight of a clean cup in grams. As an alternative, the cup may be supplied with an accurate tare weight for use with two-pan laboratory balances. Note: Do not interchange tare weights between cups as each cup and tare weight is matched.
   

2. Remove cover and fill to within 1.7mm of rim with material to be tested.
   

3. Carefully replace cover so that the air and excess material is expelled through vent.
   

4. Wipe over cover to remove surplus and reweigh. By subtracting the original weight of the cup, the weight of the contents will be found. If a tare weight was used at the start, the balance will show the weight of the contents. Clean thoroughly immediately after use.
   

5. By comparing a water sample at a temperature listed in the chart below verification of cup accuracy can be determined.