How do I test the viscosity of my paint/stain (coating)?
There are two methods. For both, if the coating needs to be thinned, use the fluid that is recommended by the coating manufacturer. Conditioning agents such as Floutrol and Penetrol make travel through the spray gun easier, but they do not thin the coating.
Viscosity Stick Method
- Using the stir/viscosity stick that was packaged with the sprayer, stir the coating well.
- Lift the stick out of the coating and hold at a 45-degree angle. The coating will stream from the stick and eventually begin to fall off in droplets.
- Monitor the rate at which the droplets fall. When the droplets fall from the stick at a rate of 1 per second, the coating is at the proper viscosity. Add a thinning agent until the droplets fall at this rate.
While this is a less precise method, it allows you to adjust the spray pattern to your comfort level:
- Fill the sprayer roughly halfway.
- Spray onto a test surface. If the finish appears rough and inconsistent, increase the air and reduce the material flow. Add a thinning agent until the spray pattern is consistent and acceptable to you in size.