Printing high density DNA microarrays is becoming more and more popular, and is invaluable for "high-throughput" screening assays, and diagnostics applications such as aCGH. A higher density array typically allows more assays to be performed simultaneously and/or, for lower sample volumes to be used for the same number of assays. The ability to print microarrays in an efficient and cost-effective manner, is of considerable interest to researchers. A major issue with using contact printing is that the array elements should be consistently and reliably positioned, and should be highly uniform. The array elements must be reproducible in size, particularly for quantifying an analyte. In this study, some available printing buffers were tested for their ability to print at high density over long print runs. The buffers were evaluated in terms of signal yield, spot merging tendency (pitch), spot size and uniformity. In addition, the effect of pin size on array density was analyzed on Aminosilane surfaces. It was demonstrated that with standard contact printer and regular substrates, it is feasible to print 50K arrays that offer high reproducibility.