Yeah the black particles appear to still happen when the fuse is set to 10 and also 100, it also doesn't seem to matter if the ignited flag is set too.
As far as i can tell this only happens with creepers too and only when they explode.
The creepers being visible kinda sucks, it would be nice to maybe implement some other way of summoning an explosion that doesn't damage blocks, if thats an easier solution.
/summon explosion ~0 ~1 ~0 {ExplosionPower:10,ShowParticles:0b}
Something like that would be cool.
Never mind, i just misunderstood how Age is used.
This case can be closed.