I use Thompson liquid form water base enamels. Everyone is making liquid / dry powder harder than it is. Temperature and firing time for these enamels remains the same. No change, unless you apply the enamel to thick. Thin is what your shooting for. After I apply my ground coat, base, black coat, white granular, and grisaille coats, I can fire up to 15 times before I start to lose my line work, evaporation. All at the same temperature, and time. Mixing is easy. I use a salad shaker from Tupperware. It has a grid at the top that breaks the enamel lumps down. You put the enamel in and add water. Enamel sinks to the bottom because the emulsion is to watery, thicken it up at little, add more enamel. The enamel is lifting or bubbling because of hand oil, wear light cotton gloves. Don't touch with bear hands. If you do touch it, wash the3 project and dry with a hair dryer. You don't need charts or any special tools for this type of enamel. All of this enamel is the same hardness. I have never found any difference in hardness. Hardness has nothing to do with lifting of bubbling. Just fire everything at the same temperature. Good luck
One more thing. After your done with the enamel, put the excess in a butter dish. When needed again, if it's still some what wet, put back into the shakes, add water and enamel and there you go. If dried hard, crush it and do the same. It's easy to revive the enamel. You don't need all the strange advice your getting. Working with this enamel and storing is extremely easy. It won't spoil or go rotten. Treat it for what it is, and don't be scared of it. If you have any more questions write me.