I had an idea tonight (dangerous I know) about how to colour the tarps. Basically I turned the tissue paper over and taped it to a scrap of cardboard then air brushed the back with Tamiya XF-57 Buff. One 'advantage' was that the tissue wrinkled so that might assist in making it look more like an old tarp.
I think that it might do for a start and as tarps end up all sorts of colours from black to browns to the off-white original then different base colours could be used.
The advantage of course is that the NSWGR stenciling and the locations of the tie down points are still clearly visible.
Some weathering of the tarp can be done later after it has been installed on a wagon.
Now, how can I make the attachment of the ropes less boring and quicker?
Somehow I don't think that there is an answer to that one.