 Busch felt his painting skills could not compete with those of the Dutch masters . He regarded few of his paintings as finished , often <unk> them one on top of the other in <unk> corners of his studio , where they stuck together . If the pile of paintings became too high , he burnt some in his garden . Since only a few remaining pictures are dated , <unk> them is difficult . His doubts regarding his skills are expressed in his choice of materials . His ground was usually chosen carelessly . Sometimes he used uneven cardboard or poorly @-@ prepared spruce @-@ wood boards . One exception is a portrait of Johanna Kessler , on a canvas support measuring 63 centimetres ( 25 in ) by 53 centimetres ( 21 in ) , one of his largest paintings . Most of his works , even landscapes , are small . As Busch used poor grounds and colours , most are heavily <unk> and have an almost monochrome effect . 
