Paintbrush as all artificats always develops its form, becomes adapted to more specialized problems (corners, paint kinds etc.). But sometimes, as says Henry Petroski, among his different debations, in his book 'The evolution of useful things', form doesn't follows function, but starts to follow fashion. Reffering to words of Viollet-le-Duc who comparing vase and it's evolution, shows 'how the form can change first for the better and then for the worse', what fashion makes with present objects.
Nowadays the painbrushes rather keep its' form since centeries and eventually change materials for more demanding liquids like solvents, varnishes etc. However form of art paintbrushes don't change much, don't get useless decorations or deformations, what could be consider as a kind of love for this traditional tool, used, as it is now, by famous painters.
