MonoCoat Reducer Monocoat does not need reduction, however it helps when you want to spray it. Use Monocoat Reducer to help preserve your leftover Monocoat in the can for a short time period. Add a half an inch on the top layer will help prevent the air getting into the product after opening. Using this reducer will help prolong Monocoat for roughly 3-4 days once opened. Q&A Q: How much Monocoat Reducer do i add in the can to "preserve" the Monocoat left in my can? A: Add a half inch barrier. Eyeing the measurement will be ok Q: Can I just use the HR Reducers?? A: No! These are not the same, at all!! Even if you are in a pinch, this wont work. Q: How much Monocoat reducer do i add to spray? A: You can add up to 25% Monocoat reducer, tip size should be 1.8 @ 25% reduction. YouTube Videos Customer Video: https://www.youtube.com/watch?v=pbra3DYuHWM .