Last summer my gf ordered some Zuzzy mats for me for my birthday. The challenges I faced in actually getting them delivered to me have been well documented in various places on the internet already, so I'll simply reiterate: don't order from Zuzzy. They have awful customer service, which is a shame because their products are really quite nice.
Ok on to the real stuff. When I did receive my items, also included in the package were several sample mats. They're not big enough to game on, but serve well as test pieces for trying out the techniques and colours for painting your large size game mats. I had tried doing a winter-themed test on one of the very small pieces I also received and had been unhappy with the results.
So I decided to try out a desert kind of theme on one of the larger sample pieces. I've got two of these large mats and want to do one up for western or post-apocalyptic types of games. Yellows, browns, greys etc. Here's what I ended up with.
I'm using various craft acrylics from Michael's on these, since painting them with miniature paints would cost a small fortune. I started out with a yellow/cream mix to dapple over top of the grey of the mat material, which was followed up by a brown wash over the entire piece.
After letting the was dry over night I mixed up a light grey colour to cover some of the flatter patches, aiming for a dry mud or cracked earth kind of feel. The dirt I mixed another batch of the yellow/cream and dry brushed on the spots that looked like sand. On top of that I used an off-white to pick up the highest spots.
Finally I went over some of the spots that would be rocks with another light grey to pick out those areas. It's not quite as desert-feeling as I'd like, but I'm actually ok with the results as they are. In retrospect, what I ended up with looks much more like the badlands I had in my mind. We were recently out in Drumheller so I had probably catalogued their look more than I'd realized. If I added some more rust / red colours it'd be almost perfect, but I think I'll probably follow a very similar patter to this when I paint the large mat.