Pointing again - sorry !

[rogyboy]

Hi guys. I'm a very experienced DIYer. I've laid 25mm Indian sandstone on 4:1 sharp sand full bed (moist to wet) as recommended on this site. I've spent days reading about all the different pointing materials but they all seem to require a permeable bed for the jointing to harden. I've seen the Marshalls video with 3:1 mortar bed and then using Weatherpoint 365 - so obviously that's OK; and yet their website says the joint is permeable ?? Paving expert says 'Joint-it' is one of the best, but can that be used on a full 4:1 bed ? I haven't had a reply from 'Joint-it'. Your advice would be much appreciated.