Do I need to add a wetting agent such as Floetrol to General Finishes Milk Paint?

No. General Finishes already adds excellent wetting and flow agents to our Milk Paint. Adding another wetting agent is superfluous, and it may even be harmful to your finish if the formulas don't coordinate.

Milk Paint can be thinned if desired with 5-10% distilled water. You can increase "open time" if needed with 10-15% GF Extender. GF Extender will improve the flow, leveling and give more working time in hot, dry climates.