50/50 Water External PVA and a little washing up liquid will hold it all in fine, Pidgeons tend to nick the stuff for their Crop and of course any livestock will dislodge it when loose also rain. But do the glue at the beginning of a warm day otherwise it is likely to not dry properly and also give a good saoking with a small spray with another drop or two of Washing Up Liquid to help the glue get in place prior to applying the glue. I use a Pint or thereabouts old Glue Container to apply the glue. Keep well clear of moving things by careful application in these area’s, also some Oil will stop humming up moving parts.OK, now I have my track laid, and it appears to be accepted by my engines. As I have included parts that are floating on the brickwork, is there any ideas on how to ballast it all without compromising the flexibility of the track and without it all immediately disappearing? Would soaking it in diluted PVA work, or am I worrying too much?