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Historic Preservation - Technical Procedures
Consolidating Delaminated Scagliola
Interior's Handbook For Historic Buildings - Jeff Greene
Lath & Plaster
Consolidating Delaminated Scagliola
CONSOLIDATING DELAMINATED SCAGLIOLA
A. This procedure includes guidance on consolidating
delaminated scagliola. Delamination may be caused by a
flaw in the original manufacture of the material. This
could include the use of glue water in the manufacture,
the use of different types or gauges of plaster for the
color coat and backing, the improper placement of the
burlap, extreme temperature changes, or the presence of
excessive amounts of moisture.
NOTE: THIS PROCEDURE SHOULD ONLY BE PERFORMED BY AN
B. For general information on scagliola, including its
characteristics, uses and problems, see 09200-05-S.
C. 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).
A. Stanley Chemical Co.
401 Berlin Street
East Berlin, CT 06023
B. Conservation Materials
P.O. Box 2884
Sparks, NV 89431
C. Maas & Waldstein Co.
Division of Seagroves Coatings Corp.
P.O. Box 187
320 Paterson Plank Road
Carlstadt, NY 07072
D. Custom Aerosal Packaging
128 East Water Street
Piqua, OH 45356
E. Sika Corporation
201 Polito Ave.
Lyndhurst, NJ 07071
A. Acrylic lacquer such as "Acryloid B-72" (10% solution) or
"Incralac" (Stanley Chemical Co.), (Conservation
Materials), (Maas & Waldstein Co.), (Custom Aerosal
Packaging), or approved equal. Available in spray cans
or 5-gallon drums.
B. Low-modulous epoxy resin such as "Sikadur Lo Mod" (Sika
Chemical Corporation), or approved equal.
C. Clean, potable water
D. Clean, cotton cloths
A. Spray gun, Binks or DeVilbiss with accessories; for
example, DeVilbiss bleeder, external mix gun with cup, or
B. Air compressor, small, portable, either gas (for exterior
use) or electric (if electricity is accessible), or
electric compressor powered by a portable generator.
C. Accessories: air hoses adequate for reaching all parts
of surface, couplers, repair kit for spray gun, small
D. Organic vapor masks, basic safety equipment to protect
operator from breathing vapors or organic solvents during
E. Goggles, to protect operator's eyes from lacquer.
F. Gloves, neoprene rubber or polyethylene disposable
gloves. Skin contact with lacquer should be avoided.
A. Verification of Conditions:
1. Determine the cause of delamination. Is there
evidence of extreme temperature changes or
excessive moisture? Is the cause of delamination
due to an inherent flaw in the original
2. Determine which type of scagliola it is - true scag
or marezzo. THIS WILL REQUIRE A CONSERVATOR'S
EXPERTISE. The biggest difference lies in how each
is manufactured, applied and finished. Marezzo is
made in reverse order from the way true scag is
produced and is generally a less labor-intensive
process. Recognizing the difference between the
two can aid in better understanding the problem or
failure. The typical polish used for each type is
also significant, as some polishes have proven to
be detrimental to the material.
A. Surface Preparation:
1. ALWAYS test repair methods in an inconspicuous area
to determine the effects of the method on the
material and whether this procedure is suitable for
use in this situation.
2. Wash area to be consolidated to remove all surface
dirt, grease and foreign matter.
a. Wipe the surface with a clean cloth saturated
in clean, clear water and mild detergent. DO
NOT FLOOD ENTIRE SURFACE, SIMPLY WIPE AFFECTED
b. Thoroughly rinse the surface with clean, clear
water and allow to dry.
3.03 ERECTION, INSTALLATION, APPLICATION
A. Apply multiple thin layers of acrylic lacquer to the
delaminated surface using a spray gun. IMPORTANT: AIR
PRESSURE OF GUN MUST BE ADJUSTED TO THE VISCOSITY OF THE
MATERIAL AND TYPE OF GUN USED.
NOTE: BRUSH-APPLIED COATINGS ARE NOT ACCEPTABLE. THEY
DO NOT PROVIDE UNIFORM COVERAGE.
1. Apply first coat in a thin mist. Solution should
be naturally drawn into the scag by capillary
2. Hand-rub surface with wet or dry sandpaper using
water as a lubricant.
3. Continue to apply thin wet coats to the surface,
hand-rubbing between coats as above.
B. Inject a low-modulous epoxy resin into the scag.
END OF SECTION