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Cement and mortar

Alkaline, porous and carbonate-bearing — which means acid dissolves it, and it damages an aluminium finish if allowed to dry on one.

What not to do

Hydrochloric acid is unsafe on Cement and mortar

Unsafe

Do not do this. The risk is established, and it is described below.

The joint dissolves faster than the deposit does, and joints do not grow back.

Evidence

Supported

Sources

  1. Cleaning & Maintenance Guidelines — Gardens & Driveways

    Marshalls plc · Manufacturer documentation

    Relied on for: That acid washing is material-dependent and that limestones and marbles are dissolved by hydrochloric acid. (inferred from the source; not stated directly)

Quicklime requires the precaution Cement and mortar

Unsafe

Do not do this. The risk is established, and it is described below.

Precautions

  • Wear gloves
  • Wear eye protection
  • Ventilate the area
  • Keep away from children and pets

Evidence

Strongly supported

Sources

  1. Right to Know Hazardous Substance Fact Sheet: Calcium Oxide (RTK 0325)

    New Jersey Department of Health, 2003 · Government or regulator

    Relied on for: That contact can severely irritate and burn the eyes and skin, that inhalation irritates the lungs and higher exposure may cause pulmonary oedema, and that long-term exposure can perforate the nasal septum and crack the skin. (states this directly)

In detail

Cement-based materials — mortar joints, render, concrete paving, screed and the grout between tiles — share three properties that decide their care. They are strongly alkaline when fresh and stay mildly so. They are porous, so oils and coloured liquids are absorbed rather than resting on the surface. And they contain carbonate compounds, which is why acid attacks them: a descaler, a brick acid or a strong bathroom cleaner used on tiled walls dissolves the joint faster than it dissolves the deposit, and the joint does not grow back. The alkalinity is a hazard in the other direction too. A standards body warns that alkaline materials such as cement and mortar quickly corrode anodic coatings if allowed to dry on the metal, which is how new aluminium windows are damaged during building work. Two further points. Pressure washing removes jointing material if the lance is aimed down rather than held at a shallow angle, and empty joints are detrimental to a pavement's performance. And efflorescence is not dirt: the stone trade's instruction is to dust-mop or vacuum it and avoid water, which dissolves the salts and carries them back in.

Properties

Sensitivity

Acids
Sensitive
Alkalis
Not applicable
Chlorine bleach
Not known
Abrasion
Sensitive
Porous
Sensitive

“Not known” means nobody has established this, not that the material is unaffected.

What works

    Detergent is safe on, in specific conditions, Cement and mortar

    Safe only in specific conditions

    This is only appropriate within specific limits, and nothing is established outside them.

    Only within these limits:

    • Structurally sound surfaces only
    • Hot water with household detergent and a stiff brush; the aim is physical removal, not killing
    • Dry completely within 24 to 48 hours
    • Correct the moisture problem first

    Named by a state health department among the materials that can be cleaned rather than discarded when mouldy: hard plastic, solid wood, concrete, metal and glass.

    Precautions

    • Ventilate the area
    • Wear gloves

    Evidence

    Supported

    Sources

    1. Mold and Moisture in Homes

      Minnesota Department of Health · Government or regulator

      Relied on for: That concrete and mortar among other hard materials can be cleaned if structurally sound, using a stiff brush with hot water and household detergent to remove the physical mould growth. (states this directly)

    2. Mold Cleanup in Your Home

      United States Environmental Protection Agency (EPA) · Government or regulator

      Relied on for: That mould is scrubbed off hard surfaces with detergent and water and dried completely. (states this directly)

    Why

    Related

    Hacks and claims involving this

    Sources for this page

    Sources

    1. AAMA 609 & 610-02: Cleaning and Maintenance Guide for Architecturally Finished Aluminum

      American Architectural Manufacturers Association (AAMA), 2002 · Standards body

      Relied on for: That alkaline materials such as cement and mortar will quickly corrode anodic coatings if allowed to dry on the metal. (states this directly)

    2. Cleaning & Maintenance Guidelines — Gardens & Driveways

      Marshalls plc · Manufacturer documentation

      Relied on for: That the lance must not be directed down onto paving because that costs jointing material, that it should be held at a shallow angle not greater than 30 degrees, and that joints should be inspected afterwards because empty joints are detrimental to pavement performance. (states this directly)

    3. Care & Cleaning of Natural Stone

      Natural Stone Institute · Trade or professional body

      Relied on for: That efflorescence is dust-mopped or vacuumed and that water is avoided. (states this directly)

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