The section When to Change Your Solvents lists the ranges of specific gravities at different states of your solvent's cleaning life. This section describes specifically how to measure that specific gravity.
- Use a cup to pour at least 400mL of your used part-cleaning liquid in a 500mL graduated cylinder.
- Use the When to Change Your Solvents table to determine what range hydrometer you need.
- Gently lower the hydrometer into the graduated cylinder and wait until it stops bobbing up and down.
- Record where on the hydrometer's graduated markings it hits the solvent's meniscus.
- Compare that value to what is in the acceptable range according to the chart in Step 2.
TIP: To reduce variation in measurements, liquids should be around 25°C (77°F).
TIP: Elma Tech A4 has a similar density to that of Figure 4 resin. Because of that, a hydrometer test will not work to test saturation. For this solvent, simply use your best judgment when examining printed parts to determine whether they are sufficiently clean. If part surfaces are sticky or shiny, it is a good indication that your solvent is not cleaning them enough.