- Evening all. Not posted on here before. Just wonder if anyone can help me. I' ve done plenty of K-REND but have got a customer who wants Parex. The rep came out to spec it and it all sounds like a science lesson, I got 3 different substrates - new blockwork, cement board and old dash. If I was doing K-REND would be Hp12 then colour for block, HPX for aquapanel then colour. For old dash which is solid would powerwash down then sbr then a 3:1 sand cement to fill out with sbr in gauging water then HP12 and colour. With Parex I'm in the dark a bit. Is there a base coat for the Parex? I got all the spec and can probably find out myself but there's nothing like hearing from people who know what they're on about. Cheers