Nothing compares the fired properties of frits as well as a melt-flow comparison. Remarkably, each frit has such a unique melting behaviour that it is possible to identify them and determine if two are similar (without knowing the chemistry). But frits need a binder to make them plastic-formable. I mix 50g of frit with 1.5g of VeeGum (or 100g/3g) then stir the powder into 40g of water in a cup. That produces a consistency that is easy to stir smooth (using a teaspoon) but is still fluid enough to level out on a plaster bat (for dewatering to plastic consistency). The 3% VeeGum is not enough to affect the melting behaviour, but it makes them pretty workable (however each frit does exhibit different tactile characteristics). I roll them into 12g (wet) balls, then dry them. They fit nicely into the reservoir for my GBMF test.
Frits are used in ceramic glazes for a wide range of reasons. They are man-made materials of controlled chemistry with many advantages or raw materials.
Comparing the Melt Fluidity of 16 Frits