This conversion doesn't work very well on solids, though it is still observable. When using SING on liquids, gases or poweders the effect is far more pronounced (and since SING creates both heat and pressure, it will convert beakable or meltable solids into other states, accelerating the rate of conversion). This means that weapons based on non-explosive SING become more powerful when used against larger targets.
One spark is enough. SING is self-replicating, converting a VERY small faction of the particles it consumes into more SING. This is not-well known and very rarely exploited, but is visible without too much trouble (spark the gun once, then select the SING element and press CTRL+F. The particle count at the top of the screen will now show how many SING particles are on-screen)