Material pills or buttons of ceramic ingredients can tell you a lot. You can make them with a 'Pill Mortar' of you can make little cubes or spheres and fire them in you kiln at the temperature you are used to.
The pills tell you how they melt -or not-, you can compare them with older batches or the same material from another supplier.
How the pill mortar works: weigh 5 grams of powder and mix it with 3 drops of water, put it in the pill stamp with a funnel. Hit on the cylinder with a hammer. Turn cylinder around and pill is ready.
Pills we made with Hein Severijns in 2015: