What does “Caulk Ratio” or “Trigger Ratio” or “Thrust Ratio” mean?

Caulk Ratio or Trigger Ratio or Thrust Ratio is a ratio of the force you generate on the trigger versus the force that is generated to push the material. This term is only applicable to manual guns / applicators.

For example, an 8:1 caulk ratio means that for every 1 kg of force the user generates on the trigger, 8 times that force pushes the material. A higher caulk ratio means the user exerts less force to get more work done. This helps reduce fatigue, especially when working with high viscosity sealants / adhesives. Dual component epoxies, polyurethanes, construction adhesives all require high caulk ratio guns.