I was afraid that you wouldn't be able to see the difference in the photos, but I could see it in person. Phrancis, if I was using non-water-based varnish I would go for disposable too since I hate using really hazardous chemicals to clean oil-based finishes. Since this is water-based, I figure I can use the more expensive brush and clean it easily. Just came back from coat 3 on the deck. I had the door open in the garage to help dissipate the fumes. About 62 degrees, and probably 40% relative humidity (is 30% outside the house based on my weather station reading, but I sprayed water in the garage). I could notice that the LPU dried much faster in the warmer, drier air compared to this morning when it was closer to 58 degrees, and I bet 50% humidity. I had to work fast to keep a wet edge (good thing I've been practicing!) Rdstarr, you were asking about what would be ideal humidity - I'd say definitely above 50%, closer to 60% would be even better. I thinned the LPU just a bit more and it helped, so this is another variable you can play with a bit if the humidity is lower. Good luck!