Previously a number of techniques have been used in order to form single crystal or pre-determined crystallography components and articles. Each one of these techniques has its own particular problems, including susceptibility to error. By utilization of a bi-crystal experiment to determine melt-back length LM and by consideration of the ingress distance d from potential initiation nucleation points on a perimeter of a seed crystal, it is possible to determine a maximum ingress length d. By ensuring that the maximum ingress length d is less than or equal to a seed crystal diameter R, it is possible to project locus from potential nucleation points C1, C2 in terms of potential radii for stray grain propagation. As the seed crystal will have a known crystalline orientation, it will be possible to consider two divergent growth curves of the crystal in terms of the stray grains propagating from the point C1, C2. In such circumstances, a connector channel can be provided with a radius r=R/4 in an area between the periphery of the seed and the locus of the stray grain maximum ingress distances d. In situations where it is found d exceeds the crystal radius R, it will be understood that the actual crystal diameter R used may be increased or adjustment made with regard to the melt-back length LM in order to alter the maximum ingress distance d.