I was born in 1965 and remember this book from when I was around 5-7.
It was about a painter that lived on a houseboat and painted abstract paintings. For some reason he broke the painting up into a bunch of small paintings and a buyer flew to his houseboat by seaplane to buy them I think the houseboat was near San Francisco. It was a large book, hardback, and illustrated.
Perhaps this one? ‘Day of the painter’ Duard G. Slattery A very grown up story about a painter who starts his day by reading a grown-up newspaper (the stock market quotations) to find out how much money he has, then takes his paints out to the dock and throws them, drips them, pours them, splashes them on the canvas in the mud below because he’s an abstract expressionist.. He walks on the canvas, shoots it (with a gun), cuts it into abstract shapes, and awaits the art dealer who flies in every day to make his selection; pocketing a large sum, the painter throws the remaining panels out to sea. This is his day, every day–painting more pictures, making more money, checking his earnings in the grown-up newspaper
I think that’s it! Now the quest is on to find a copy!
Thank you!
The Horse’s Mouth?