The Limited Color Pallet

Right now I'm working on a group of acrylic New Mexico/Arizona pieces which will be up in two group-show galleries in August. I am trying something with these that I haven't done much of before: using a limited color pallet. Here are the only colors that I'm using-

(That's ultramarine blue -red shade, permanent rose, light green permanent, titanium white and cadmium yellow medium.) Limiting the color pallet is great for keeping the pieces more cohesive and also for staying with the color strategy initially decided on. Will have to have to use this trick more often. 

And here's a preview-

Rather jumbled/disorganized looking right now but not for long...I will post the finished pieces and that should be very soon since the deadlines are looming.