White marks can be caused by physical contact or moisture and temperature. Random chalky marks will typically settle down once curing is complete, but can be removed by gently wiping with a soft or damp cloth. Bloom may be remedied by air and sunlight, though it often requires light sanding and another coat of paint.
Efflorescence is the white powdery substance formed on the wall surface due to water seeping into the exterior wall. When water enters a wall and later evaporates, it leaves various soluble salts on the surface, disfiguring the wall. Efflorescence occurs on different building surfaces, such as bricks and concrete.
I'd try brushing it off with a stiff brush first. Try a small area first to get the pressure right so you don't take the paint off, just the salt deposit. Wear a mask and thoroughly vacuum your work area when you're done. If you don't have one, maybe pick up a cheap humidity meter and monitor the humidity in that room.
Chalking occurs due to ultra violet (UV) radiation from sunlight interacting with the constituents within the paint film. Over time UV degradation of the binder or resin within the paint film will allow the exposed pigment particles to become more loosely bound to the surface. A powdery surface is the result.
Efflorescence and alkali salts can be removed by dry brushing with a stiff bristled brush followed by wet sponging the surface with a mild 5% solution of white vinegar (acetic acid) in water. The whole area should then be wiped down with a damp cloth and allowed to dry thoroughly.
A cellulose sponge and some warm water should work to remove chalk on the walls but if it does work use some 409 multi surface cleaner or simple green.
Mix one cup of white vinegar into a bucket of warm water, and use a soft sponge to tackle stubborn stains. You can also try using washing-up liquid and warm water. For glossy finishes, which are less durable when it comes to cleaning, avoid harsh substances and consider using heat instead.
How do you dust walls? Always start at the top of the wall and use a vacuum with an extendable wand and dusting brush, a clean microfiber mop, or a microfiber duster to remove dust and cobwebs. Work your way down the wall lightly skimming the surface with the brush or duster.
Despite its name, white mold can appear as a white, grey, or green powdery fungus depending on the surface it's growing on. It includes multiple fungal species like penicillium and aspergillus. Regardless of the species of white mold, you'll commonly find it in high moisture areas of a building.
If little or no chalk remains and the old paint is in good condition, no priming is necessary. If light to moderate chalk remains, use a penetrating additive to the first coat of water-based paint to help the paint film bond to the chalked surface.
White, non-gel toothpaste may be applied to satin or glossy finish painted walls. Place a small amount on the end of a cotton swab or a clean toothbrush and gently work back and forth over the mark. Use a clean, damp cloth to remove any residue. Allow the area to dry.
Wash the surface down using water and mild detergent in conjunction with a stiff brush to remove any excess chalk and allow to dry.
The acidity in the vinegar helps remove the efflorescence and calcium deposits by breaking down mineral crystals. After cleaning the surface, let dry for 48-72 hours (moisture content below 25%).
Brush and rinse as much of the chalk stain from the surface as possible with a sponge. Remove the remaining chalk stain with a damp sponge and Soft Scrub. With a clean, damp sponge, remove any remaining Soft Scrub.
Efflorescence appears when water evaporates from the wall. They have a crystalised, chalky appearance and feel grainy to touch. Salt efflorescence on internal walls is made up of a mix of chemicals such as calcium carbonate, sodium and potassium.
Mix up a 3:1 solution of water and vinegar (any kind), put the solution in the affected pot or pan (make sure to completely submerge the mineral deposits), and turn heat it up on the stove. Once the water starts to get near boiling, shut off the burner, and let the hot liquid dissolve the mineral buildup.
Paint chalking is a common defect where the paint film degrades, leaving a powdery residue on surfaces over time. Exposure to weathering and UV light, low-quality paint, inadequate surface preparation, and incorrect application contribute to paint chalking.
This white powdery substance forms on the surface of these materials and can be caused by several factors. The primary cause of efflorescence is the migration of water-soluble salts from within the wall material to the surface, where they crystallize as water evaporates.
Hydrogen peroxide: Mix hydrogen peroxide with warm water in a 1:1 ratio, then apply the solution to the affected area with a stiff-bristled brush. Allow the solution to sit for several hours or overnight, then rinse the surface with clean water.
The easiest way to differentiate between the two is via a water test. Spray a small quantity of water on the suspected substance. Efflorescence will quickly dissolve, while mold growth will remain. The mold growth will likely mat down a bit, so look carefully for lingering material.