First, look at the choice of wood and canvas frame work, if it is too rough frame easily deformed, will cause the screen to paint not the same as pulling appear crack.
Second, look at fabian perez prints Rab latitude and longitude lines straight is not straight, whether discontinuity generated wavy lines.
Third, look at paintings have not painted a good primer, primer typically gelatin or chemical glue, white latex, is coated with a protective coating on the canvas. If there is the side of the frame, you can see whether done at the end.
Fourth, there is no oil was observed on the varnish, there is no protective layer. Generally it requires dry before painting the varnish, and the picture is dry six months to a year.