The most effective advice to eliminate saltpter and mold from the walls

1 metal brush
a bottle of hydrochloric acid
1 brush
container with water and soap
concrete
sealing the sealant
Painting

Wear a mask, gloves and glasses to protect your eyes. Using the metal brush, remove all the saltpeter from the surface of the walls.

Mix a glass of hydrochloric acid with three glasses of water and mix with the brush until you mix them perfectly.

Apply the solution using the brush. A foam will be created that will be left to rest for 5 minutes. Then rub the wall with soap and water, rinse and clean.

When the wall is dry again you can apply the cement to put it back in place and then the sealant. This step may not be necessary.

Allows the cement to dry, then apply some coats of paint to restore the wall to its original appearance.