Historic Preservation - Technical Procedures
Removing Wood Stains From Concrete
Hstrc Concrete: Investigation & Rpr/Pre-Conf Training - 1989
Removing Wood Stains From Concrete
REMOVING WOOD STAINS FROM CONCRETE
THE CLEANING OR REMOVAL OF STAINS FROM CONCRETE MAY INVOLVE THE
USE OF LIQUIDS, DETERGENTS OR SOLVENTS WHICH MAY RUN OFF ON
ADJACENT MATERIAL, DISCOLOR THE CONCRETE OR DRIVE THE STAINS DEEPER
INTO POROUS CONCRETE. USE THE PRODUCTS AND TECHNIQUES DESCRIBED
HERE ONLY FOR THE COMBINATIONS OF DIRT/STAIN AND CONCRETE SPECIFIED.
A. This procedure includes guidance on removing wood stains
from concrete using a hypochlorite solution.
B. Wood stains on concrete may appear as yellow or brown in
color. Stains from rotten wood may appear as chocolate
brown in color.
C. Safety Precautions:
1. DO NOT save unused portions of stain-removal
2. DO NOT store any chemicals in unmarked containers.
3. EXCELLENT VENTILATION MUST BE PROVIDED WHEREVER ANY
SOLVENT IS USED. USE RESPIRATORS WITH SOLVENT
4. No use of organic solvents indoors should be
allowed without substantial air movement. Use only
spark-proof fans near operations involving
5. Provide adequate clothing and protective gear where
the chemicals are indicated to be dangerous.
6. Have available antidote and accident treatment
chemicals where noted.
D. See 01100-07-S for general project guidelines to be
reviewed along with this procedure. These guidelines
cover the following sections:
1. Safety Precautions
2. Historic Structures Precautions
4. Quality Assurance
5. Delivery, Storage and Handling
6. Project/Site Conditions
7. Sequencing and Scheduling
8. General Protection (Surface and Surrounding)
These guidelines should be reviewed prior to performing
this procedure and should be followed, when applicable,
along with recommendations from the Regional Historic
Preservation Officer (RHPO).
NOTE: Chemical products are sometimes sold under a common
name. This usually means that the substance is not as pure as
the same chemical sold under its chemical name. The grade of
purity of common name substances, however, is usually adequate
for stain removal work, and these products should be purchased
when available, as they tend to be less expensive. Common
names are indicated below by an asterisk (*).
A. Glycerol (C3H8O3):
1. A sweet syrupy hygroscopic trihydroxy alcohol
usually obtained by the saponification of fats and
used especially as a solvent and plasticizer.
2. Other chemical or common names include Glycerine;
Glyceryl hydroxide; Glycyl alcohol; 1,2,3-propanetriol; Propenyl alcohol.
3. Potential Hazards: FLAMMABLE.
4. Available from chemical supply house, drug store or
B. Sodium Hypochlorite (NaOCl):
1. An unstable salt produced usually in aqueous
solution and used as a bleaching and disinfecting
2. Other chemical or common names include Bleaching
solution*; Household bleach*; Laundry bleach*;
Solution of chlorinated soda*.
3. Potential Hazards: CORROSIVE TO FLESH.
4. Available from chemical supply house, grocery store
or supermarket, hardware store or janitorial supply
Job-prepared Hypochlorite: Made by user, see 03710-01-S
for guidance on preparation.
1. Calcium Hypochlorite (CaCl2O2):
a. A white powder used especially as a bleaching
agent and disinfectant.
b. Other chemical or common names include
Chlorinated calcium oxide; Bleaching powder*;
Calcium oxymuriate*; Chloride of lime*;
Chlorinated lime*; Hypochlorite of lime*;
Oxymuriate of lime*.
c. Potential Hazards: CORROSIVE TO FLESH;
FLAMMABLE (WHEN IN CONTACT WITH ORGANIC
d. Available from chemical supply house, dry
cleaning supply distributor, drugstore or
pharmaceutical supply distributor, janitorial
supply distributor, swimming pool supply
distributor, or water and sanitation supply
2. Sodium Orthophosphate:
a. Other chemical or common names include
Tribasic sodium phosphate; Trisodium
orthophosphate; Trisodium phosphate; TSP*;
Phosphate of soda*.
b. Potential Hazards: CORROSIVE TO FLESH.
c. Available from chemical supply house, grocery
store or supermarket or hardware store.
C. Clean, potable water
D. Accessible source of water, soap and towels for washing
and rinsing in case of emergencies associated with the
use of chemicals
A. Stiff, natural bristle brushes
B. Clean, dry cloths
1. Provide adequate wash solutions (i.e. water, soap
and towels) before starting the job.
2. Whenever acid is used, the surface should be
thoroughly rinsed with water as soon as its action
has been adequate. Otherwise it will continue
etching the concrete even though the stain is gone.
3.02 ERECTION, INSTALLATION, APPLICATION
NOTE: DO NOT TRY MORE THAN ONE TREATMENT ON A GIVEN AREA
UNLESS THE CHEMICALS USED FROM PRIOR TREATMENT HAVE BEEN
A. First, scrub the surface thoroughly with a solution of 1
part glycerol in 4 parts water.
B. Next, scrub the stained area with a hypochlorite
solution. Use job-prepared hypochlorite (see 03710-01-S
for guidance on preparation), or dilute 1 part household
bleach (5% sodium hypochlorite) with 4 to 6 parts water.
C. Rinse thoroughly with clean, clear water and allow to
D. Repeat the process as required to achieve the desired
level of cleanliness.
END OF SECTION