theres so many things that can be going on with this one Ruddez, that my poor little one finger typing couldnt keep up with , but i can only give you a couple of heads up tips that i use , they have served me well up now , and i can list them' but sand is different for starters , up and down the U.K , what sand i use maybe different to what you can get hold of , but hey ho here goes , . I like to use sovereign waterproofer and mix it to the water ratio rather than cement ratio , sand can wet and sand can to dry so the amount of water you put into a gauge changes , but you add waterproofer to the water the amount will be the same throughout the gauges you use ,
Sand , i like to use a soft washed and a soft sharp and mix them as i think best , so again with in this case a dashing 1st coat i would mix soft and sharp to equal ammounts ,so the heavy stone content from the sharp would help in stopping water ingress .