Black and White and Painted Versions of Raised Tiles from Porto, Portugal

I finished painted the raised yellow and white tiles I saw in Porto, but I find that I need to work on my grime technique. Because the tiles are raised and have various nooks and crannies and are outside, they get dirty in the crevices. It’s darker than the shadows but not quite like I painted. Who would have thought painting dirt and grime would be a technique to master?!