Skip to main content

Historic Preservation - Technical Procedures

Spectitle:
Sealing Terra Cotta

Procedure code:
0421405R

Source:
National Capitol Region Specifications - Agriculture Bldg

Division:
Masonry

Section:
Terra Cotta Unit Masonry

Last Modified:
02/24/2012

Details:
Sealing Terra Cotta



SEALING TERRA COTTA


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on sealing terra cotta
         units which have lost their surface glaze.

    B.   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

         3.   Submittals

         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).  

1.02 REFERENCES

    A.   American Society for Testing and Materials (ASTM), 100
         Barr Drive, West Conshohocken, PA 19428, (610) 832-9585
         or FAX (610) 832-9555.


PART 2---PRODUCTS

2.01 MANUFACTURERS

    A.   ProSoCo, Inc.
         755 Minnesota Avenue
         P.O. Box 1578
         Kansas City,  KS  66117
         800/255-4255 or 913/281-2700

2.02 MATERIALS

    A.   Terra Cotta Sealing Materials: One-part, opaque, water
         base exterior masonry coating, containing silicone resin
         binders, that has excellent UV stability and allows at
         least 90% moisture vapor transmission based on ASTM E96,
         such as "Conservare BMP" Breathable Masonry Paint
         (ProSoCo, Inc.), or approved equal.  NOTE: Test all
         colors and receive approval from RHPO that color match is
         acceptable.

    B.   Water: Clean, free of oils, acids, alkalis and organic
         matter.


PART 3---EXECUTION

3.01 PREPARATION

    A.   Protection:

         1.   Protect persons, motor vehicles, surrounding
              surfaces of building whose masonry surfaces are
              being restored, building site, and surrounding
              buildings from injury resulting from masonry
              restoration work.

         2.   Erect temporary protection covers over pedestrian
              walkways and at points of entrance and exit for
              persons and vehicles which must remain in operation
              during course of masonry restoration work.

         3.   Protect sills, ledges, windows, and projections
              from sealing material droppings.

3.02 ERECTION, INSTALLATION, APPLICATION

    A.   Areas to be sealed: Areas to be sealed are only patches
         of the terra cotta units which have lost their surface
         glaze. Lightly brush spalled areas to remove loose
         material and glaze that has failed but not fallen from
         face of unit.

    B.   Clean terra cotta with sponge and clean water before
         sealing:

    C.   Prime areas to be sealed with specified primer using
         brush or roller application, strictly adhering to
         manufacturer's recommendations. Promptly remove all
         primer from surrounding surfaces. Test small areas of
         terra cotta and gain approval of manufacturer's
         representative and Contracting Officer before proceeding.
         Allow primer to dry 10 hours before applying masonry
         coating.

    D.   Apply breathable masonry paint in two coats, strictly
         adhering to manufacturer's recommendations. Brush apply
         first coat, wait 24 hours and brush apply second coat.
         Color shall match adjacent terra cotta units. Test small
         area of terra cotta and gain approval of manufacturer's
         representative and Contracting Officer before proceeding.

                         END OF SECTION