This is one of the most common questions that I hear from students.
When my students say "I think I'm done", the first clue is the word "THINK", and that tells me they are not sure. Believe me, you will learn to know when you are done with a painting, but first you have to give the process time. Being finished with a painting is when you become one with the painting, all is in order, all has been addressed, and you are at peace and harmony with the painting.
When I also hear: "I like it and don't want to mess it up by doing more" that's another additional clue it is NOT done! Generally one quick look and it's clear: there are things the student is happy with, but you must always go further. If you only have one coat of paint on your painting, it is not done; if you only have two coats of paint on your painting, it is still not done. You can NEVER get depth in a painting on just one or two coats of paint. The more layers on the painting, the richer it becomes. Even on a wall in a new house, one coat of paint never covers fully, two coats looks better, and then the color becomes rich with a third coat, and we're just talking about a solid color wall! You should never be afraid of going further with your paintings. You should continue to paint on them until you are content, happy, fulfilled, and at peace with your paintings. You WILL know when a painting is done, but you have to give it time.
You know when you are in love, you get that feeling, that tingle, that natural high. You are excited, content, fulfilled, and you have a glow about you. It is the same with a painting. If you have not had this feeling with a painting, then you have not finished painting it.
I have painted on a painting for weeks, only to cover it up with gesso or modeling paste to start over again. Then when it is a painting I am happy with, when it is a painting that says something, when it is a painting that I love, when it is a painting that I want to put on my wall, then and only then is it finished.
If I ever have a question of "Is it finished?", I put the painting to the side in my studio where I can see it often. I continue to look at it and think about it, and then one day I find that painting back up on my easel and I am back at it again. A really good painting takes time, and thought, and energy, and it takes your breath away and makes you feel connected and in love. It sounds a little silly, but it is true. It is not always easy to find someone and fall in love with them, and it is not always easy to pick up a brush and paint a masterpiece. Love happens when you least expect it, and so does the magic of creating a great painting. A great love is worth waiting for and a fantastic painting is worth the extra time to get it there!
NEVER rush a painting: it is art, it is creativity, it is "One of a Kind!" Make it yours, make yourself happy, make it a piece of work you will love forever. Even if you sell your art, if you are not happy with it, the client will not be happy with it either. You MUST always go further to create real magic in a painting, so stay with it: do not be too excited to be finished, never rush it and just enjoy your time with the painting. Make it special, make it complete and when you are satisfied, when it gives you that warm feeling inside, when you have edited the piece fully, then sit with it and feel comfortable with it. When you are content, when you are zen, when you are at one with the painting, then are you done? Don't just think you are done, know you are done, feel it.
Take your time: do not be afraid of your painting, take a risk, challenge yourself, be bold, be brave and remember my favorite line "There is always more paint." If you ever doubt whether a painting is done or not, it most likely is NOT done. Time is important: give your love of painting the time it needs to go from Okay, to Good, to Great! Make it You, make it work, and most importantly, do not rush it: have fun with it, give it energy, give it life, give it uniqueness, give it parts of you. Make your viewer see what you see in the painting. Express yourself and allow everyone to see that.
Have fun! Life is short: paint what you want, paint when you want and paint how you want. Be a true artist and fall in love with your paintings, and then you will know when you are finished with the process.