To Prime Or Not To Prime - TilersForums.co.uk | Tile Forums

cornish dave · 27-05-2008

Hi all, would you prime green grade plaster board, and what do you think off topps flexi powder addesive is it any good

**whitebeam** · 27-05-2008

With moisture resistant board, British Gypsum reccomend it's pva'd before it's skimmed I would prime and the flexi from topps seems good, really creamy.

**grumpygrouter** · 27-05-2008

Depends what addy you are using. I am using White Star straight onto the stuff at the moment.

If i was using bagged stuff, I would have primed.

**sWe** · 27-05-2008

The answer on wether or not to prime on what substrates, is really simple: read the specs on the bag/tub of adhesive... If it doesn't say, it's almost certain that it's a crap adhesive.

cornish dave · 27-05-2008

hi i prime and use bagged its nice to know what others think never to old to learn thanks

**pjc** · 27-05-2008

never prime plaster board always use cement based :Pete

**grumpygrouter** · 28-05-2008

Quote:

Originally Posted by pjc

never prime plaster board always use cement based :Pete

It is interesting that BAL stipulate to prime plasterboard with APD if using cement adhesive but Ardex specify no primer required for their cement based addy's!

**dock** · 28-05-2008

hi

generally no priming required on plasterboard;

for ready mixed adhersive - will slow down set time......can be quite dramatic
for cement based ..........there is no calcium sulphate to isolate .....fixing to paper

purpose of priming plaster with primer G in our case, but use a good quality acrylic.........and NOT PVA, is to isolate cement from the calcium sulphate in the plaster. If in contact it can lead to the formation of ettringite (calcium sulpho aluminate hydrate). These crystals grow with time and have been known to force tiling off the wall.

dock