A method for forming a three-dimensional article through successive fusion of parts of at least one powder layer provided on a work table in a build chamber, which parts correspond to successive cross sections of the three-dimensional article, said method comprising the steps of: providing at least a first powder tank (64, 74) and at least a second powder tank (64, 74); providing a first type of powder in said first powder tank (64, 74) having a first particle size distribution; providing a second type of powder in said second powder tank (64, 74) having a second particle size distribution which is different to said first particle size distribution, wherein the smallest particle size in said second particle size distribution is smaller than the smallest particle size in said first particle size distribution, wherein the smallest particles in the first particle size distribution is at least three times as large as the largest particles in the second particle size distribution; distributing a first sub-layer of said first type of powder on said work table; distributing a second sub-layer of said second type of powder on top of said first sub-layer of said first type of powder, where said first and second sub-layers are forming one of said at least one powder layers; and fusing said first and second sub-layers with a high energy beam from a high energy beam source so as to form a first cross section of said three-dimensional article, wherein the work table is at a height while the first sub-layer of the first type of powder is distributed on the work table or a previously applied powder layer; and the work table is at the same height while the second sub-layer of the second powder type is distributed on top of the first sub-layer of the first type of powder, wherein the thickness of the layer is equal to the distance between the top of the build chamber and the surface of the work table or a previously applied powder layer. providing at least a first powder tank (64, 74) and at least a second powder tank (64, 74); providing a first type of powder in said first powder tank (64, 74) having a first particle size distribution; providing a second type of powder in said second powder tank (64, 74) having a second particle size distribution which is different to said first particle size distribution, wherein the smallest particle size in said second particle size distribution is smaller than the smallest particle size in said first particle size distribution, wherein the smallest particles in the first particle size distribution is at least three times as large as the largest particles in the second particle size distribution; distributing a first sub-layer of said first type of powder on said work table; distributing a second sub-layer of said second type of powder on top of said first sub-layer of said first type of powder, where said first and second sub-layers are forming one of said at least one powder layers; and fusing said first and second sub-layers with a high energy beam from a high energy beam source so as to form a first cross section of said three-dimensional article, wherein the work table is at a height while the first sub-layer of the first type of powder is distributed on the work table or a previously applied powder layer; and the work table is at the same height while the second sub-layer of the second powder type is distributed on top of the first sub-layer of the first type of powder, wherein the thickness of the layer is equal to the distance between the top of the build chamber and the surface of the work table or a previously applied powder layer.