Don’t use a brush. Trying to paint lattice with a brush is a pain in the ass. The secret: use spray paint.
I’m building a railing for my deck, using lattice for the middle area so my kids don’t kill themselves on the 6 inch drop off the deck (yeah – inches). The deck and frame for the railings are built; I just have to cut the lattice to fit the railing frames, paint them, then figure out how to attach the railing frames to the deck (I didn’t install posts).
I first started using a brush to paint the lattices and it took FOREVER to do one side. I said fuck this and bought 6 cans of spray paint instead, doing four lattices in the time it took me to do one with a brush.
So save yourself some time and patience: use spray paint for lattices.