New plaster

[hyscore]

Do I need to prime new plaster walls before tiling is so whats best.Thank you.

[Dave]

I use bal APD or BAL bond sbr....there plenty other makes out there....

I always advise priming..especially if using cement based adhesives or you will get a reaction between the adhesive and the Gypsum in the plaster....

BAL Prime APD

A modified acrylic polymer dispersion for use as a primer for a variety of backgrounds/bases prior to fixing ceramic tiles, mosaics and natural stone and prior to the application of levelling compound and the BAL WP1 TANKING SYSTEM. BAL PRIME APD isolates products containing calcium sulphate such as gypsum plaster and anhydrite screeds from cement-based adhesives, thus minimising the risk of reaction between the two materials.

Also suitable for use on cement:sand rendering, blockwork, plasterboard, cement:sand screeds and timber. It also provides surface strength to friable surfaces and reduces the porosity of porous backgrounds/bases, thus preventing the formation of air bubbles and prolonging the flow time with levelling compounds and extending the open time of tile adhesives. The primer is blue in colour to help ensure that a complete and even coating is obtained.
BAL Bond SBR

A waterbased polymer with a wide variety of uses in the construction industry, particularly as an admixture and bonding agent for cement and concrete applications. Once cured, the polymer is water and frost resistant. BAL BOND SBR can be used as a slurry coat when mixed with hydraulic cement or gypsum plaster, as a multi-purpose admixture for cement:sand mortars, concrete and gypsum plaster; as a brush applied primer, sealer or dustproofer.

Suitable for use on cement:sand screeds, toppings or renderings, plastering, waterproofing, bonding, concrete repair, priming and sealing.

[whitebeam]

I prime new plaster, Recently I've had to strip existing tiles and adhesive they just fell off, not mine I might add.

[Pawelzik]

Regarding your question if priming on plaster walls (gypsum based, not cement based) or gypsum based wall boards is a MUST:
Gypsum based plaster and gypsum based wall boards: Yes, always - to prevent reaction between the cement based adhesive and the gypsum in the plaster.
Gypsum based wall boards with paper covering: Not a MUST but strictly recommended to prime the boards to prevent them from moisture destroying the gypsum and also to prevent reaction between the adhesive and the gypsum in the plaster.
This is German rule but as this is normal physics (reaction of moisture vs. gypsum, reaction gypsum vs. cement) it should be valid for the UK as well.
Martin.

[grumpygrouter]

Originally Posted by Pawelzik

Regarding your question if priming on plaster walls (gypsum based, not cement based) or gypsum based wall boards is a MUST:
Gypsum based plaster and gypsum based wall boards: Yes, always - to prevent reaction between the cement based adhesive and the gypsum in the plaster.
Gypsum based wall boards with paper covering: Not a MUST but strictly recommended to prime the boards to prevent them from moisture destroying the gypsum and also to prevent reaction between the adhesive and the gypsum in the plaster.
This is German rule but as this is normal physics (reaction of moisture vs. gypsum, reaction gypsum vs. cement) it should be valid for the UK as well.
Martin.

Martin it is good to have your input to the forum. To get ideas and perspective from other countries and methods is interesting, keep it up. Thank you.

Oh! your English is very good too!

Grumpy

[Varley]

It does require priming with an acrylic primer, as to which primer to use I would use one from the same manufacturers as the adhesives you are using, eg, if you use Bal adhesive then use BAL Bond to prime, if you use Granfix adhesive then use their primer. This way you are covered by the manufacturers if anything goes wrong. Hope this makes sense.

[hyscore]

Thanks fot the info Guys.
Would BAL APD be the one to go for? I am going to use a Bal adhesive.cheers

[grumpygrouter]

Originally Posted by hyscore

Thanks fot the info Guys.
Would BAL APD be the one to go for? I am going to use a Bal adhesive.cheers

Absolutely fine.

Grumpy

[hyscore]

Originally Posted by grumpygrouter

Absolutely fine.

Grumpy

Thank you.

[Proper Job]

depending where you seek your info out on this question there is a lot to take into account background, type of plaster used, atmosphere and temp. Some guides give 24 -48 hours per 1 mm thickness others state 28 days. The reason why 28 days is recommended is because thats when it has reached its max bond to the surface, it might look dry with in 5 days, but putting large format tiles on it i would not recommend until then. All plastered surfaces should be really primed i always do either with mapei or bal bond. If using bag stuff it must be primed at all costs it could have a reaction. In wet areas you should use some kind of tanking i use the mapei Gum it drys like rubber well recommended and pretty cheap i have used dunlop in the past and not bad either but a two coat process. Ok well that covers the plaster skimmed surface. Now for fixing weights its 20kg per sqm for skimmed plastered boards ands 22kg per sqm for unskimmed some people say up to 32kg this would be up to a 6 - 8 mm notched trowel size not bed which a lot of people get confused with, by the time you have pressed the tile in to the troweld adhesive your creating about 3 - 4mm solid bed of adhesive, the further you pack out the adhesive which not recommended you are decreaseing the weight you can fix.

Hope this helps guys and girls or girls and guys.