Tempera Batik is one of the favorites of my students. But as an artist
I love using this medium .
what works for me is, I use tempera as thick as I can make it. Let dry overnight before applying the india ink. Then dry also the india ink before soaking the artwork a few minutes in a basin of water . tapping from under flakes off the india ink. for special effects, I put the art piece under the faucet and spurt water on the painted surface.
The tempera brand probably matters also.
Hope this helps.
EDSAMAIL. Internet the way YOU WANT IT.