When to Give up on a Painting

This is a painting in flux.

I often tell my students that acrylics are wonderful because they are so easy to paint over.  This is true, but eventually texture build up can become the enemy.  When this happens it can become more and more frustrating to apply paint because the attempt to conceal a previous layer’s texture interferes with the intentions for the painting.  So after layers and layers of paint and hours lost, when do you throw in the towel?  At some point all you can do is ask yourself, “am I really accomplishing anything?”  A few days ago I was in a similar predicament with another painting (it has just been one of those weeks).  I plowed ahead and I am now really happy with the outcome.  After hours of frustrations something clicked and a successful painting emerged.  Today, however, feels different.  I think I am much further away from where I want to be.  So, I have a decision to make.  To throw way or to keep at it?