Apply deep primer

Should one definitely apply primer under the paint in new buildings?
A painter says it is sufficient to just paint the walls with water, because using primer seals the wall and prevents it from breathing.
We want to use a silicate paint from the company Sto.

Hello !! Say sometimes sometimes.. Info painter Primarily, a primer is meant to provide a better bonding bridge, meaning more precisely, the product you apply after the bonding bridge adheres better. But if you want to be 100% safe, there are also bonding bridges specifically for silicate paints. I also think that the company Sto seals it, asking doesn't cost anything. Best regards.

Primer as an adhesion bridge???

Tell me, Jackal, where did you pick up the idea that primer is an adhesion bridge? This is an underlying consolidator and hardener that also regulates absorbency with the correct setting (dilution). If on a low-absorption substrate such as gypsum board or plaster the primer remains on the surface and not enough is absorbed by the substrate, surface glossy spots form and you actually achieve the opposite, a reduction in adhesion. What do you actually do for a living that you recommend and spread such nonsense?

Tell me, Schakal, where did you hear that primer is an adhesion bridge? This is a substrate hardener and hardener that also regulates absorbency with the correct setting (dilution). If on a weakly absorbent substrate such as e.g. GK or plaster the primer remains on the surface and is absorbed too little by the substrate, surface gloss spots form, you achieve the opposite, a reduction in adhesion. What do you actually do for a living that you recommend and spread such nonsense.

100% agreement Regarding the statement to paint the walls with water, I can only say that I have never heard such nonsense. Everyone is happy when the walls are dry. Regards Thommi

And now to you Meier!! But before I start, some information for you What I do professionally, etc., is none of your business, that's settled, and if you want to ask me something or correct me, I have no problem with that. Maybe everyone can be wrong once or as you write it, well, it's not my taste. Sure, I could have extended my feedback and explained it in more detail, but that's not what it was about. But now back to the other point: Do you actually know that there are tons of products especially for Tiefengrund and [Haftbrücken]??? There are even some that have both in one, for your information Copy-Net Tiefengrund Primer and sealant for substrates. To be used indoors and outdoors for priming before applying new coatings, plasters, and tiles on walls and floors. Primers are available in LF (solvent-free) and LH (solvent-based). Solvent-based primers should only be used outdoors because the odor nuisance indoors is enormous. For indoor use, therefore, use solvent-free Tiefengrund. Tiefengrund has two functions: 1. To strengthen crumbly or chalking substrates and 2. To form an adhesion bridge between the substrate and the subsequent coating. Regards.

The contributions from Schwarzmeier are almost all like that. Apparently, he needs to vent some aggression here. He rarely contributes anything productive. Pitiful, but presumably there have to be such people as well. Just put him on the ignore list. He really doesn’t deserve any more attention.

Depending on the type, the primer does not prevent breathability. Even though breathing is a tricky matter anyway. Just because a wall offers a certain possibility to "breathe" doesn’t mean it actually does.

A wall should be able to absorb and release moisture up to a certain extent in order to balance fluctuations. Nothing more. Most primers do not prevent that.

Not all of them stabilize the surface but all "equalize" the properties between different materials, e.g. plasterboard and filler joint.

Best to contact Sto inquiries, they can give precise information about which primer is suitable in the specific case.