Six flavours and colour charge
The six quark flavours are up, down, strange, charm, bottom and top. Colour charge is a separate property governing strong interactions, not a visible pigment. Flavour, colour, electric charge and mass identify different aspects of a particle and should not be treated as interchangeable labels.
From nucleons to hadrons
Protons and neutrons are hadrons built from quarks and gluons. Simple valence descriptions use three quarks for baryons and a quark–antiquark pair for mesons. These are useful starting patterns, not an exhaustive catalogue of composite states. Elementary leptons, including electrons, have a different classification.
Confinement and experimental evidence
High-energy collisions do not release quarks as ordinary detached building blocks. Strong-interaction processes produce other composite particles, whose tracks and decay products are measured. Scattering patterns, jets and agreement across experiments provide evidence for quark descriptions without requiring a photograph of an isolated quark.
References: [1]
Collective behaviour at high temperature
Experiments at extreme temperatures and densities investigate quark–gluon plasma, where ordinary separate-proton and neutron descriptions become inadequate. Such work explores strong interactions and early-universe matter. It does not imply that normal heating simply disassembles everyday materials into free individual quarks.
References: [1]