How to repair and clean lime after saltpeter?

I have some humidity coming in every winter, and I do not want to talk about this here of course.

The problem is about a great quantity of saltpeter.
The plaster is natural hydraulic lime.
I have read that I should brush it and then oil it.
Is this true, what oil etc?
Or what else?
I have to brush and brush because it grows again all the time.

Can I do something while it is still wet or wait (long...) that it dries?
Thanks

Boy, I wish I could help but this is out of my range of experience...Anyone else want to weigh in on this? Dan

Hello,

Potassium nitrate efflorescence is what I "think" you are describing?

I need more information before I can give any good counsel, and photos would help tremendously.

Source and age of the lime?

Any mixed additives?

Did you do the work yourself?

What is the wall matrix itself (what is the wall made of)?

Do you have any additional interstitial issues of moisture or nitrates in the wall or foundation system?

Is the foundation well drained?

Regards,

j

I just know this is called saltpeter by the diccionary, but it correspond well to the name salitre in Spanish and salpètre in French!
This is white and looks like salt.
This lime is 2 years old, is natural hydraulic lime with no aditive.
Under this lime is rock only in most parts. But one part is on cement, with also natural soil under (mixed stones with some earth)
And one part is lime on "red clayed thermo bricks". Sorry for the lack of name, they are red bricks that are hollow inside, same as the ones in cement for building.
So the problem does not seem to be linked to the kind of support.

The walls have no fondation, this is all on a rocky soil including behind walls.
The basis is very dry, I have inflitrations from above.
We are little by little filling the cracks with lime, and you cannot help about the cause of the problem (I would have written in another part of the forum for this), we already do it slowly. This is a cliff.

So about the finishes, I ask for a solution about the consequence of this humidity, because this salt is falling down regularly.
I want to stop it forming.
At the moment I just brush from time to time.

Hi Xisca,

I really need photos to understand it better. From your description of the wall matrix, I suspect that the concrete (OPC) could be to blame (source.)

...I have infiltrations from above...

This must be stopped and could well be the accuwater for the salts. The water runs through the OPC and perhaps a deposit in the stone (rare) as you are close to the ocean, and this deposits the salts as inflorescence on the surface of the plaster. If there is a chimney near this location that is most likely the source, and I should have asked if there was or if the stone came from an old chimney. Either way, the water infiltration from the top must be mitigated. Poultice desalination is required of clay and/or some other sequestering agents.

Here is some additional info you may find useful:

Poultices - The true or plain poultice and the cleaning and desalination of historic masonry and sculpture

Soluble Salts in Masonry

A generic syllabus to understand possible steps

Regards,

j

I just correct a slight misunderstanding....
There is no chimney nor chimney stones: This is natural ROCK, from a cliff.

I have this also where there is NO concrete at all.

As I mentionned, yes I do solve the problem little by little, but this is the same as for people having fungi: even when the problem is solve at the root, you still need to do the CLEANING!