Can you tell me what keeps water getting in between the plaster
and the blocks?
What kind of sealer can you put on the blocks if you dont have
acrylic clear finish? and dont want to use plaster?
Acrylic paint and acrylic glazing are very similar. They are both water-based. We do not recommend varnish - it will completely seal the blocks; they need to breathe.
It is also possible to use no finish. White wash worked for Tom Sawyer and the California missions.