Klinker - Selection water absorption 10 to 12 percent

Hello,

the brick we have chosen has a water absorption of 10 to 12 percent.
Is that okay?
The building materials dealer said up to 15% would be OK and nowadays there are no bad bricks, but he also wants to sell.
I see online limit values of up to a maximum of 6% or 10% but I can't find a consistent statement.
Is there anything else to watch out for?

Here is a photo of the brick...

I would say you don't need to worry about that. The clinker will not act like a sponge and absorb water in the rain; it is more about the water it takes from the mortar during masonry. Both pre-wetting help against this, and there is a suitable mortar recipe for every "taste."

I mean, not that the stones effloresce over time!

That has nothing to do with the water absorption capacity.

Isn't it true that the absorbed water "flushes out" the efflorescence agents?

What matters is how much salt is introduced into the masonry, which then becomes visible on the surface. From my point of view, this has nothing to do with the "storage capacity" of the stone. Then real clinker brick should never effloresce, since it does not absorb water.