Those are extremely good looking molds. You mention porcelain powder. Is this the same as is used in plates and cups? I, too, would love to see the baits they make.
Porcelain powder
Molda Super is a high strength formulated plaster used in sculpture, modelling, general casting applications requiring high strength, and is also used in construction material formulations.
see here
http://www.saintgobainformula.com/Products/Plaster/Molda-SuperI use this
Alternative for plaster, very fine powder with SUPER results.
Add 25% water, mix & ready, no klods
For very hard, smooth molds without airbubbles
For glossy baits add 3 layers 2 k varnish or boat varnish
2 layers varnish thinned with 10% thinner & 1 or 2 layers pure varnish