Do you brush gesso on, is it even necessary?

are there any alternatives, perhaps something better or easier to use. I just dont seem to understand what the purpose of using gesso on canvas, rather than just leaving the canvas as is and painting directly on it.Do you brush gesso on, is it even necessary?
never paint gesso OVER oil paints - as a water based medium it will not adhere permanently to an oil base. Always oil over water, never water over oil. Yes it is ok to paint acrylics directly onto ';raw'; canvas (gesso is also acrylic) Gesso is a primer that diminishes the absorbency of cotton or linen canvas. In the case of oil painting, however it is more importantly a barrier between the fabric and the paint itself. Without this protective barrier oil paint will rot the canvas in time.


Prestretched canvases and canvas board are already primed with gesso and require no other prep.Do you brush gesso on, is it even necessary?
Gesso is useful when you want to create a very FLAT surface for your painting. I would recommend it for bare canvas, but it is not absolutely essential. You'll find that this flatter surface obtained from application of gesso to a canvas, gives you an easier time with your brushwork as you will not be ';fighting'; against the rough texture of the surface with each brushstroke. ---Steve S.
Usually you only gesso a canvas if there's alright paint on it you want to cover up, but if you're painting with acrylics it's fine just to paint on the canvas.