A Tech question for anyone really

[Diamond Pool Finishers]

OK as most of you are aware, i tile swimming pools, we like to do our own sand/cement substrate
IYO should we use a primer before we apply tile adhesive/mosaic or is to not necessary ??
just for the record we never do use primer!
BUT WHY ? what is advantage/or disadvantage please ?

 

[White Room]

I only use primers when it's to separate two substances from each other, cement based addy to gypsum for example or to regulate any excessive suction/dusty surface on the backing...if i was using a cement based addy onto render and it was new then I would'nt unless under the manufacturers advise.

 

[DHTiling]

I Only prime cement screeds etc if they are rather friable/dusty.. if not then just burn in with adhesive for key.

I also prime if i am SLC'ng..

 

[Peter]

Same as above, if it's a non dusting sand cement screed I will just tile straight over it. Would prime if dusty to 'lock it in' and then prime for SLC to stop it drying/sucking too quickly.

 

[tommyzooom]

I was taught that, unless you have a good reason for priming, then dont prime just for the sake of it, as you are adding two potential points for failure,
between the primer and the substrate
and between the primer and the adhesive.

 

[Ajax123]

All screeds should be primed if thereis a risk of suction which can cause the adhesive to become friable and poorly hydrated. However as most sand cement screeds are tiled after aut 6 weeks ish there is little likelyood that they will be dry so priming becomes less of an issue.

In your particular case david I would say that priming is unlikely to be of benefit and in fact could be counterproductive. I say this on the basis that if you tile and then fill the swimming pool with water any primer (unless epoxy) is likely to be adversely affected by the presence of moisture/alkali due to the pool becoming saurated and the primer beingin contact with cement and also possibly by the chemicals in the swimming pool water.

I would hazard a guess that when you do your own sand cement you use plasticisers and possibly SBR anyway which will also help reduce suction issues.