Hi Karla
For the Intonaco use only copletely dry sand and lime not less than four, five month old. If you apply it on arricciato of about 1cm thick it takes about twenty minutes to set for painting. Using expanding mesh like Gary suggest is very handy. prepare "sheets" of thin cement or lime-sand, add some red pigment (oxid of iron)or other to the mortar and dry for future work. This technique called Ferrocementand is used for building. Employing Fresco takes lots of patience and some experience which you can get only by experimenting and learning from your mistakes. Good luck Yoram