Unfortunately, the pink coloration disappeared as the NaOH was neutralized. Too bad for me, I wanted the pink splatters to remain.

"Plaster Remains Indicator"
In addition to the chemical reaction experimentation, I was also interested in the unfired clay bowls slaking away from the interior plaster shell as though they shed their skin.

"Plaster Remains NaOH"
I used different clay for this bowl. I foud it less successful due to the similarities in color.