from what i have been reading, latex interacts with cement in interesting ways, creating a water resistant bond. there are latex additives specifically designed for adding to concrete. but if you get a paint with a decent latex content, you can come pretty close.

i mixed 2 parts cement with 1 part sand, and then added cheap “mistake” paint ( the stuff that had a wrong color mix and is being sold for cheap at homedepot ) until it had a like an adobe paste texture, then spread it over the screen.

On the screen itself, i did an initial thin coat paint of just cement and paint, that was more fluid. it dries rigid, and makes spreading the later paste stuff easier.

it dries with cracks, but i just left them. i think i could limit the cracks by doing more thin layers, or just painting over the outside with an outdoor paint at the end