Page 201 - Green - Maritime Archaeology: A Technical Handbook. 2nd ed

180 Maritime Archaeology: A Technical Handbook, Second Edition
Figure 6.7 The general factors involving tilt in a perspective view of a square grid frame.
This starts with one print being laid down and then successive prints in the run, with half the overlap cropped out, are matched to it. Adjacent runs are mounted in the same way and the runs matched together. There are always problems doing it in this way, as often the adjacent strips of photographs will not match exactly.
It is advisable to use a stiff card or board for mounting the photomosaic (Bristol board is recommended) and a thin PVA glue for paste up, partic- ularly when using resin-coated (RC) paper, because it allows the prints to slide on the board. The most effective means of cropping prints for photo- mosaics is by feather-edging. To do this, the surface of the photographic layer of the print is lightly scored with a sharp scalpel. This should be done carefully so as not to cut too far into the paper layer. The print is then turned over, folded along the score mark, and torn in a diagonal motion while holding the side of the print to be retained with a finger. This creates a very thin, clean-cut edge to the photograph, which gradually thickens up to the full paper thickness at 10 to 20 mm from the edge. When stuck down, it pro- duces a smooth flat surface without unsightly, thick-cut edges that cause shadows and crinkles. A small piece of stiff plastic can be used to smooth down the prints and to remove bubbles from under the print. Excess PVA glue can then be wiped from the surface of the mosaic with a sponge. A