Hello I am Rahul from India.
After reading the papier mache recipe tips regarding use of Hydrostone I tried my own recipe with Plaster of Paris in my mache pulp for my face shaped flower vases. I added only one spoonfull the effect was an excellent increase in smoothness. Along with Papier mache I used home made glue, white adhesive, boiled linseed and Plaster of Paris. The mix was very workable ie, more workable than a simple mixture and it dried smoothly.

Thanks to all