A nontrivial, simply connected,
rational homotopy type is called irreducible, unless it is the product of two nontrivial
rational homotopy types. In this paper previous results are extended by proving that
every finitary, simply connected rational homotopy type having positive weights is
representable as the product of a unique set of irreducible types. On the
way to this unique factorization result, it is proven that (in the rational
homotopy category) retracts of positive weight types again have positive
weights.