Not so in the old days. Most if not all painters in the Renaissance had to make a living taking on painting jobs, most from the nobility. We call them artistic paintings nowadays, but their patrons bought them or commissioned the jobs for the rendered superior craft skills. It was not uncommon for famous painters during that period to prepare certain colors by themselves. And it would only be reasonable for a painter to keep those particular color ingredients as his trade secret, so that he could render his paintings differently from other painters in the trade. To be good at his trade, a painter had to deliver a better painting through better craft skills using better supplies and tools. Those master pieces that could stand the test of time will be those that were better both in terms of craft skill and creativity.
Recently I read about the story of late famous Chinese painter Qi Baishi (齊白石). His paintings are now periodically auctioned worldwide at astronomical prices. Master Qi's paintings demonstrably delivered superb craft skills and he therefore asked for higher prices for his paintings then his contemporaries. And like all clients, his clients liked to bargain for a better price. There are many stories about the business side of this famous painter. For example it was said that when his clients entered his old studio in Beijing, they would first see a big sign: "I charge my paintings irrespective of friendship. Please respect yourself and pay according to my stipulated prices without bargaining" 賣畫不論交情，君子自重，請照潤格出錢。
And how did master Qi price his paintings or painting jobs?
There was one interesting story: he charged one dollar for one little chicken. Once a client asked him to paint five chickens and bargained to pay four. It had to be an old or important client, because finally he did paint five little chickens for him - with the last one half-hidden behind a tree! Similarly he had a fixed charge for each shrimp. And when an old client begged him to paint one more for him. He finally agreed and painted one more for him. All shrimps looked lively and energetic except this last little one. "I will give this one for you free, because it is already dead", master Qi said.
|Master Qi Baishi painting at his studio in Beijing|