Hi all, i have four showers to tile from scratch, cement board lined.

[Luggsey]

I have 20l of Nassboards latex tanking paint but am unsure if a primer is required?
The substrate is cement board which is clean and not dusty.
If I do need a primer can I use 50/50 PVA or must it be something expensive!
I have also been looking for a good value tape for the joints and am put off paying £1+ per metre for it!
I found a supplier that sells 100mm wide fibreglass matting tape for £16/50m. It's the sort of fibreglass tape used with resin but I see no reason not to use it with latex paint? Anybody tried using this?
Thanks for any advice.
Paul.
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I have 20l of Nassboards latex tanking paint but am unsure if a primer is required?
The substrate is cement board which is clean and not dusty.
If I do need a primer can I use 50/50 PVA or must it be something expensive!
I have also been looking for a good value tape for the joints and am put off paying £1+ per metre for it!
I found a supplier that sells 100mm wide fibreglass matting tape for £16/50m. It's the sort of fibreglass tape used with resin but I see no reason not to use it with latex paint? Anybody tried using this?
Thanks for any advice.
Paul.

This is the tape.