Remove saltpetre efflorescence and salt efflorescence
- What is nitric acid? "> How does the efflorescence occur?
- Variant 1 - brushing
- Variant 2 - Use nitrate remover or saltpeter remover
- Variant 3 - Remove plaster
- 1st crack treatment
- 2nd horizontal barrier
- 3. Outer seal
- 4. Inner seal
- 5. Veiling seal
In older houses, whitish deposits often appear on the walls. Especially in the basement or in the lower part of the walls are affected by saltpetre efflorescence or salt efflorescence. Often this problem is caused by moisture in the old masonry. However, it is important to determine the cause of the saltpetre efflorescence before treatment.
In old walls often lack the seal to the ground or to the outside. As a result, the walls pull moisture out of the ground, which then manifests itself in the form of these white saltpetre and salt efflorescence. Which problem is exactly the reason for the annoying crumbly white residue on the wall, must be investigated before the elimination, so that the correct treatment for the respective case can be initiated. The removal of saltpetre will not help if the cause is not removed afterwards. Therefore, in the following instructions, we will not only show you how to remove the salt efflorescence, but also the various methods of remediation for the walls.
You need this for the removal:
- Rough brushing
- protective clothing
- gloves
- Quast
- bucket
- chisel
- hammer
- Rotary hammer with chisel
- nitrate remover
- Saltpetre remover
What is nitric acid?
Many building materials contain salts, including gypsum, cement or lime. The white saltpetre efflorescence that you find on your wall is basically just a salt. The name nitric acid is a bit confusing because this visible part is a nitrate, ie salt. Nevertheless, you should always wear gloves when removing saltpeter, because as long as the nitric acid is moist, it can cause severe damage to the skin. Especially allergy sufferers have big problems with all forms of saltpetre. 
How come the efflorescence ">
Methods for the renovation of masonry at a glance
- crack treatment
- horizontal barrier
- outer seal
- waterproofing
- veil seal
Remove saltpetre efflorescence and salt efflorescence
Variant 1 - brushing
Many dry saltpetre efflorescences can be easily brushed just like simple salt efflorescence. However, that does not mean you've eliminated the problem with it. Even if no saltpetre is visible on the outside, it still sits inside the wall and will certainly hit again in damp weather. Therefore, you will only get along with simple brushing if only a small area is really affected, which you then rehabilitate, as described in point four of the interior renovation below.
Variant 2 - Use nitrate remover or saltpeter remover
Various manufacturers offer both nitrate remover and saltpeter remover. When buying, pay attention to which area can be cleaned with a liter. About 10 to 15 square feet should be removed with a liter of cleaner. Strong acids are at work in the cleaner, so wear special gloves that are acid resistant. Since the saltpeter remover is usually quite fluid, you should absolutely protect your eyes from splashing. The cleaners are usually suitable for various materials such as bricks, concrete or clinker. Check on the packaging whether the selected product is really suitable for your purposes.
- Wipe the wall
- Apply cleaner with Tassel or thick brush
- to act according to instructions
- rinse with clear water
- Cleaner mixture should not get into the wastewater
- Protect the environment
Tip: The nitrate remover should not be used in direct sunlight. If you use the remover outdoors, you should protect the surrounding plants. For this, the ornamental plants should be dug up. Before you later dig these plants back into the adjacent soil, it may be necessary to replace the soil here as well. You should also cover plastic windows and door frames before applying the cleaner.
Variant 3 - Remove plaster
If the plaster, especially in the lower part of the wall, is soaked in saltpetre and moisture, it must be completely removed before rehabilitation is possible. But you notice that usually immediately, because a part of the plaster will have already solved in this case. For this purpose, first the plaster on the outside of the house should be knocked off. Especially here a lack of sealing against the oppressive groundwater is often the cause of such damage.
Tip: As a developer of a new building, you should pay close attention to ensuring that this work is carried out properly. Many home builders have had to run for years because their entire house was not habitable because of mold and moisture. Find out in depth or hire an independent surveyor to check the work. Even if that will cost a few hundred euros, that's nothing compared to the damage.
Unfortunately, if the damaged area is in the basement area, you must first dig the soil to the bottom of the basement so that you can work safely here. Below under point three of the renovation, we show you the seal, which you should then apply to the basement walls.
Only when the outer wall has been exposed, you should also refuse the plaster inside. The inside will later be refurbished last. How the renovation is carried out indoors, we show you under point four.
Tip: The harmful nitrate, however, still sits in the now open brickwork even after the plaster has been knocked off. Therefore, these exposed wall parts should also be treated with nitric remover, as described in point two.
Thoroughly rehabilitate masonry permanently
1st crack treatment
Before the masonry can be sustainably remediated, all cracks must be closed. Pay attention to the special sealants with synthetic resin, so that you do not immediately produce saltpeter efflorescence or saline efflorescence through the wrong material. Lime plaster or lime cement plaster should not be used in this case as these materials attract moisture again.
2nd horizontal barrier
In many old houses, it may be necessary to cut off the entire wall below, so to speak, to insert a sealing foil or tar paper. To do this, you will go on piece by piece and remove either a layer of stones in the basement or on the ground floor at ground level. But always work only about a meter of wall, so that the overlying wall does not slip.
When you have taken out the stones, a sealing cardboard or a foil is inserted and the stones with the appropriate mortar put back. Use a special clean-up mortar that does not contain lime. This removes the possibility of the wall constantly pumping up moisture on the ground.
3. Outer seal
The foundation and the basement area must be completely protected from the outside against moisture penetration. For this, of course, first the soil must be removed. Subsequently, either a water-repellent coating is applied or a barrier layer is built by appropriate tar paper or welding tracks. The welds must be well sealed at the joints and seams. The cleaner you work here, the greater the success and, above all, the longer you have peace of mind from further moisture damage.
Tip: A combination of thick film and tar paper has proven to be particularly effective and durable in most severe cases. If the tar paper is glued directly into the still thick film, a durable seal of the wall is created.
4. Inner seal
If you have completely cut off the plaster inside, you can now apply a special barrier plaster, which is impermeable to water because of its ingredients. If the plaster is still present, but the damage is quite extensive, the experts recommend the application of sealing slurries. For minor damage, which has already been remedied by removing the saltpetre efflorescence or salt efflorescence, a water-repellent coating with a special color is quite sufficient.
- slight damage - water-repellent color coating
- moderate moisture damage - waterproofing slurry
- heavy damage with plaster cut off - re-plaster with barrier plaster
Tip: If it is a slight saltpetre damage, please check if it is really that light and why it is. Maybe it's just the beginning of a bigger problem. Then laminating with a water-repellent coating helps nothing.
5. Veiling seal
The term veiling does not really apply. Actually, these are many small injections with a special gel, mostly acrylic. The wall is provided with small offset holes, in which then this gel-like material is injected. The pores in the masonry should absorb this mass and thus no longer have the opportunity to suck moisture from the bottom or from the outside.
In a double-shell masonry, of course, the injections are carried out from both sides. Of course, this method is much simpler than the type of horizontal sealing by foil or roofing felt, described under point two. 
Tip: Many companies have specialized in the injection method. However, there are also black sheep, who are only briefly in one place active. Always trust in a specialist who is truly resident. Ask the Chamber of Crafts if the company is registered there and ask the company to provide reference properties nearby. If the company really has successes, it will surely call you satisfied customers.
Tips for quick readers
- Determine the extent of the damage
- in the basement wall outside expose
- Efflorescence brush off in case of slight damage
- Apply nitric remover or nitrate remover
- Wash remover with water
- in the event of severe damage, knock off the plaster
- then compulsory refurbishment
- Repair cracks in the masonry
- Insert horizontal barrier
- Seal the outside of the wall and protect against moisture
- Seal inner wall with thick coating or slurry
- or sealing by injections with special gel
