07-23-2016, 09:32 AM
To add to what Barry said, you use a viscosity cup to measure and sometimes adjust the viscosity of whatever you want to spray. Many finishes are intended to be used at the viscosity they come in the can. In that case, you would measure the viscosity, look up on the chart what N/N combination is recommended for that viscosiity for your gun type, and start there. You might have to make a small adjustment in viscosity to fine tune how it sprays but you wouldn't be making any major dilutions. The other way around, diluting to adjust the viscosity to fit the gun N/N you have is much less desirable. Finishes start to run more easily, you have to apply more coats, etc. Sometimes, you have no choice, but it's almost never optimum.
Here's one source for a Ford #4 viscosity cup.
John
Here's one source for a Ford #4 viscosity cup.
John