Page 354 - Construction Waterproofing Handbook

8.14 CHAPTER EIGHT
● Acidic
● Organic
● Alkaline
Cleaners are toxic, and should be used by trained personnel wearing protective cloth-
ing. Cleaners should be applied in sample areas, so that damage such as etching of
stonework does not occur. Adjacent envelope components, including glass, metals, and
vegetation, should be completely protected before cleaning.
OSHA, EPA, state, and local regulations control chemical cleaner usage, including their
collection and disposal. Most municipalities will not allow chemicals to reach city drainage,
surrounding soil, or groundwater. Some cleaners have formulations that are neutralized after
rinsing with water; others do not. It is important to investigate manufacturer’s recommen-
dations and local codes to prevent unlawful use or disposal of chemical cleaners. Refer to
Chap. 11 for additional hazardous waste use and disposal regulations.
Chemical cleaners are necessary when water cleaning does not suffice and abrasive clean-
ers cause too much substrate damage. Removing paint with chemical cleaners only requires
rinsing to remove paint residue after cleaner application. It is often necessary to repeat appli-
cations several times when previously painted layers are excessive or several different paints
have been applied. With lead-based paints, waste from cleaning must be treated as hazardous
waste, properly collected, removed, and disposed according to government regulations.
Cleaners are also available for stain and pollutant removal from substrates. These substances
include asphalt, tar, and metallic and efflorescence stains. The cleaners remove specific areas
of stains on a substrate in conjunction with general pressure cleaning or soaking (Table 8.3).

Poultice cleaning
When existing stains or pollutants have penetrated a masonry surface, water and chemical
cleaning are often not sufficient to remove staining. If abrasive cleaning is not acceptable,
poulticing may be an alternative method. With poultice cleaning, an absorbent material
such as talc, fuller’s earth, or a manufacturer’s proprietary product is applied to a substrate.
This material acts to draw stains out by absorbing pollutants into itself. The poultice is then
removed from the substrate by pressure cleaning.
The length of time a poultice must be left on a substrate to absorb pollutants varies with
the stain type, pollutant penetration depth, substrate porosity, and general cleaner effec-
tiveness. This cleaning is especially effective on natural stone substrates such as limestone,
marble, and granite. Poultice-type cleaners are effective on a wide range of stains, includ-
ing oil, tar, primer, solvents, paint, and metallic stains from hard water (Table 8.4).
Substrate testing with various types of available cleaning systems should be completed
to determine the most effective system that does no harm to facade and adjacent materials.

TABLE 8.3 Chemical Cleaning Properties

Advantages Disadvantages
Little damage to substrate Environmental and safety concerns
Ease of paint removal Clean-up and disposal requirements
Various formulations and strengths available Damage to surrounding substrates and vegetation