Cleaning Darkened Or Discolored Travertine
- Procedure code:
- Apt Bulletin, V. 23, N. 2 (1991), Doebly, Lewin & Aronson
- Last Modified:
CLEANING DARKENED OR DISCOLORED TRAVERTINE
A. This procedure includes guidance on cleaning darkened or
B. Travertine naturally darkens over time. The iron
compounds in the stone, when combined with oxygen,
eventually produce a dark reddish-brown tone.
C. Travertine may also darken from accumulations of
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. Synthetic detergent containing sodium dodecylsulphonate
and marketed for use in home laundry, such as "FAB"
detergent, or approved equal.
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
Calcium Hypochlorite (CaCl2O2):
1. A white powder used especially as a bleaching agent
2. Other chemical or common names include Chlorinated
calcium oxide; Bleaching powder*; Calcium
oxymuriate*; Chloride of lime*; Chlorinated lime*;
Hypochlorite of lime*; Oxymuriate of lime*.
3. Potential Hazards: CORROSIVE TO FLESH; FLAMMABLE
(WHEN IN CONTACT WITH ORGANIC SOLVENTS).
4. 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 distributor.
C. Clean, dry cloths
D. Clean, potable water
A. Garden hose
B. Stiff bristle brushes and/or acrylic mesh pads
C. Paint rollers (for large surface areas)
D. Squeegees and/or wet/dry shop vacuums.
A. Surface Preparation: Conduct test on small area to
determine time required to remove the soiling without
3.02 ERECTION, INSTALLATION, APPLICATION
NOTE: THE EFFECTS OF THIS PROCEDURE ARE ONLY TEMPORARY. THE
STONE WILL AGAIN, OVER TIME, DARKEN DUE TO THE REFORMING OF
IRON OXIDE ON THE SURFACE OF THE STONE.
CAUTION: ACIDIC AND ALKALINE CLEANERS WILL ETCH TRAVERTINE
AND MAY INTRODUCE SOLUBLE SALTS INTO THE POROUS MATERIAL.
CAUTION: CLEANERS CONTAINING SODIUM CARBONATE OR ACIDIC
PHOSPHATES ARE HARMFUL TO TRAVERTINE AND CAN DAMAGE THE
NOTE: WHEN CLEANING, AVOID OVERCLEANING. AIM FOR ACHIEVING
85% CLEAN. MOST DAMAGE OCCURS WHEN ATTEMPTING TO CLEAN THE
NOTE: BEGIN CLEANING BY USING THE GENTLEST METHOD POSSIBLE.
TEST CLEAN A SMALL AREA BEFORE ATTEMPTING TO CLEAN LARGE
AREAS. TEST IN AN INCONSPICUOUS LOCATION.
A. Thoroughly wet the surface to be cleaned.
B. Apply synthetic detergent in a 1-2% aqueous solution.
1. For small areas, scrub the surface with stiff
bristle brushes and acrylic mesh pads.
2. For large areas, apply with paint rollers and allow
to remain on the surface for the length of time
determined by previous testing.
C. Thoroughly rinse the surface with clean, clear water and
allow to dry. For interior applications, contain liquids
using squeegees and wet/dry shop vacuums.
D. If some soiling still remains, scrub with a 5-1/4%
solution of sodium hypochlorite or calcium hypochlorite,
or apply cloths soaked in bleach.
CAUTION: BLEACH CAN IRRITATE THE SKIN AND CAN CAUSE
BLISTERING OF EYES AND MUCOUS MEMBRANES. IT IS ALSO
TOXIC IF INGESTED. WASH HANDS THOROUGHLY AFTER USE.
END OF SECTION