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How to Use a Paint Viscosity Cup

How to Use a Paint Viscosity Cup

Viscosity - the state of being thick, sticky, and semi-fluid in consistency, due to internal friction.

Using a viscosity cup for painting can drastically simplify and improve your painting but you need to know the right cup to choose for your coatings.

Whether your spraying wood finishes, industrial enamels, or anything in between a paint viscosity cup allows you to know just how thin your paint is. Additionally knowing the viscosity of your paint allows you to have a reference range so you can select equipment settings that will let you achieve a consistent result when painting.

To select a viscosity cup that will match the needs of your painting you can check the technical data sheets (should be available online of the manufacturers site) and see if a cup is referenced. You can then consider a viscosity cup conversion chart that shows the range of viscosities a particular cup can measure. Ford 4 Cups cover one of the greatest ranges of viscosities and are also generally more affordable.

Once you have selected a viscosity cup the next thing is to know the desired viscosity ranges of your coatings. Once you know the desired ranges you can add thinner until the coating is within the desired viscosity range.

After confirming the coating is properly thinned you would then right down the time the material took to begin breaking the fluid stream and this would give you your viscosity. With the viscosity range written down you then begin setting your paint application equipment to achieve the proper appearing finish you want. If you are unable to achieve the desired finish, try to see if your viscosity is to high (the paint is to thick) and add thinner as indicated on the technical sheet. With the viscosity written down and the equipment settings adjusted you will have a repeatable formula to achieving a paint finish.

It is important to allow the paint to stabilize at room temperature, or at whatever temperature you intend to measure the viscosity and spray at. Remember temperature will change the viscosity of your material. Measure the temperature for your records.

Quick Tips:

  • Hold viscosity cup by handle & completely submerge into paint.
  • Have a small container ready to place under the cup.
  • Hold stop watch ready to start.
  • Be sure to place your finger under the orifice to prevent the paint from running out of the cup. Pour in the paint then remove finger.
  • As soon as paint flow from cup breaks, stop the stop watch.
  • Check time on stop watch to Technical Data Sheet.
  • If time is out more than 2 -3 seconds either side, add reducer
  • Test again

The Gun Man shows what a Viscosity Cup is and how to use it in this step by step video on Mixing Automotive Paint Correctly to Specifications. He has also taken some time to explain how to read a paint can and what everything means. Demonstrate using Standox Crystal Pro Clear HS, DuPont Centari 6000 Basecoat and also Duxone clear.