This morning's work on Catcott Burtle(about 45 mins), saw the rhyne bed painted a darkish grey emulsion colour, then coated with a thick layer of PVA (first of about 4 or 5 coats). A couple of patches of Silfor were added to gauge effect. The area with the rails etc is still bare cork with the grey/red primer mix, the ground cover and ballasting yet to be done (modelling clay for general surface including siding, fine granite or such on the 'mainline'.).
PVA is just white wood working glue, I guess you can get it world wide. Some brands dry clearer than others. I use the one in the dark green bottle, either Evostick or Unibond (cannot recall, not being anywhere near the bottle at present - well the glue bottle anyway). I've often thought that that varnish is too shiny (odd thing to say I know), it showing up any dust present and being more the colour of best bitter rather than mucky water. I've never seen rich blue water either apart from in the Med, around the UK it's gerally shades of grey with hints of brown, depending on how much mud is in it (the nearby Thames the other week was the colour of tea with all the mud in it after the heavy flooding rain). Any blue, will just be the reflection of a blue sky.