Paints For Exterior Masonry Walls i I BUILDING MATERIALS AND STRUCTURES REPORT BMSllO UNITED STATES DEPARTMENT OF COMMERCE NATIONAL BUREAU OF STANDARDS BUILDING MATERIALS AND STRUCTURES REPORTS On request, the Superintendent of Documents, U. S. Government Printing OfiBce, Wash- ington 25, D. C, will place your name on a special mailing list to receive notices of new reports in this series as soon as they are issued. There will be no charge for receiving such notices. An alternative method is to deposit with the Superintendent of Documents the sum of $5, with the request that the reports be sent to you as soon as issued, and that the cost thereof be charged against your deposit. This will provide for the mailing of the pub- lications without delay. You will be notified v/hen the amount of your deposit has be- come exhausted. ' — If 100 copies or more of any report are ordered at one time, a discount of 25 percent is allowed. Send all orders and remittances to the Superintendent of Documents, U. S. Government Printing Office, Washington 25, D. C. The following publications in this series are available by purchase from the Superintendent of Documents at the prices indicated: BMSl Research on Building Materials and Structures for Use in Low-Cost Housing 10^ BMS2 Methods of Determining the Structural Properties of Low-Cost House Construc- tions 10^ BMS3 Suitability of Fiber Insulating Lath as a Plaster Base 16^ BMS4 Accelerated Aging of Fiber Building Boards 10^ BMS5 Structural Properties of Six Masonry Wall Constructions 15^ BMS6 Survey of Roofing Materials in the Southeastern States 15^ BMS7 Water Permeability of Masonry Walls* * BMS8 Methods of Investigation of Surface Treatment for Corrosion Protection of Steel.. 10^ BMS9 Structural Properties of the Insulated Steel Construction Co.'s "Frameless-Steel" Constructions for Walls, Partitions, Floors, and Roofs 10<f BMSIO Structural Properties of One of the "Keystone Beam Steel Floor" Constructions Sponsored by the H. H. Robertson Co 10^ BMSll Structural Properties of the Curren Fabrihome Corporation's "Fabrihome" Con- structions for Walls and Partitions 10^ BMS12 Structural Properties of "Steelox" Constructions for Walls, Partitions, Floors, and Roofs Sponsored by Steel Buildings, Inc - 15c BMS13 Properties of Some Fiber Building Boards of Current Manufacture 10^ BMS14 Indentation and Recovery of Low-Cost Floor Coverings 10^ BMS15 Structural Properties of "Wheeling Long-Span Steel Floor" Construction Spon- sored by the Wheeling Corrugating Co • 10^ BMS16 Structural Properties of a "Tilecrete" Floor Construction Sponsored by Tilecrete Floors, Inc • 10^ BMS17 Sound Insulation of Wall and Floor Constructions 204 Supplement to BMS17, Sound Insulation of Wall and Floor Constructions 5^ BMS18 Structural Properties of "Pre-fab" Constructions for Walls, Partitions, and Floors, Sponsored by the Harnischfeger Corporation 10^ BMS19 Preparation and Revision of Building Codes • • - BMS20 Structural Properties of "Twachtman" Constructions for Walls-and Floors Spon- sored by Connecticut Pre-Cast Buildiners Corporation 10^ BMS21 Structural Properties of a Concrete-Block Cavity-Wall Construction Sponsored by the National Concrete Masonry Association • • 10^ BMS22 Structural Properties of "Dun-Ti-Stone" Wall Construction Sponsored by the W. E. Dunn Manufacturinsr Co 10^ BMS23 Structural Properties of a Brick Cavity-Wall Construction Sponsored by the Brick Manufacturers Association of New York, Inc •4;"V","*m-r' BMS24 Structural Properties of a Reinforced-Brick Wall Construction and a Bnck-Tile Cavity-Wall Construction Sponsored by the Structural Clay Products Institute 15^ BMS25 Structural Properties of Conventional Wood-Frame Constructions for Walls, Par- titions. Floors, and Roofs ^^'^ SMS26 Structural Properties of "Nelson Pre-Cast Concrete Foundation" Wall Construe- tion Sponsored by the Nelson Cement Stone Co., Inc 10^ BMS27 Structural Properties of "Bender Steel Home" Wall Construction Sponsored by the Bender Body Co BMS28 Backflow Prevention in Over-Rim Water Supplies BMS29 Survey of Roofing Materials in the Northwestern States • 15^ BMS30 Structural Properties of a Wood-Frame Wall Construction Sponsored by the ••• '"^ Douglas Fir Plywood Association • BMS31 Structural Properties of "Insulite" Wall and "Insulite" Partition Constructions Sponsored by The Insulite Co • *0trt of print. [List continued on cover page Hi] Paints for Exterior Masonry Walls by * CLARA SENTEL ISSUED NOVEMBER 15, 1947 Building Materials and Structures Report BMSllO UNITED STATES DEPARTMENT OF COMMERCE • W. Averell Harriman, Secretary NATIONAL BUREAU OF STANDARDS • E. U. Condon, Director I UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1947 FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS. U. S. GOVERNMENT PRINTING OFFICE, WASHINGTON 25, D. C. PRICE 15 CENTS Foreword Data on the relative durability and performance of four general classes of masonry paints are given in this report. Out-of-door weathering tests were conducted to determine the serviceability of paints applied to wall specimens constructed of new and used common brick; cast concrete; stone-, cinder-, and lightweight-ag- gregate-concrete block; and wood frame with cement-asbestos shingles. Formulas for the paints and erection of the wall sections are described, as well as methods for applying paint to the specimens. Ratings based on the weathering characteristics and performance of each type of paint and evaluation of painting methods for coat- ing diflferent surfaces are given. Painted specimens which are discussed in detail in the body of this report were exposed to atmospheric conditions in Washington, D. C, for a period of approximately three years. Results of the same tests for a 6-year period are shown graphically in the ap- pendix. Conclusions are for the conditions of test described. E. U. Condon, Director. [ill Paints for Exterior Masonry Walls by Clara Sentel ABSTRACT Four classes of masonry paints, cement-water, resin-emulsion, oil-base, and synthetic- rubber, and one whitewash were applied to test wall specimens of new and used com- mon brick; cast concrete; stone-, cinder, and lightweight-aggregate-concrete block; and wood frame with cement-asbestos shingles to determine the durability of such paints on masonry surfaces. Specimens, exposed to atmospheric conditions for approximately 3 years, were rated on weathering characteristics. Durability of the paints was deter- mined on the bases of type of paint used, type of surface coated, methods of applica- tion and curing, and conditions of casting and painting. Page CONTENTS Lightweight - aggregate - concrete Page (4) block 16 II Foreword (5) Cast concrete 16 (b) I. Introduction 1 Performance of coatings on surfaces not usually painted 16 II. 2 Materials (1) Used common brick wall speci- 1. Paints - 2 mens 16 (a) Cement-water paints 2 (2) New cement - asbestos shingle - (b) Resin-emulsion paints 3 faced wall specimens 17 (c) Oil-base paints 4 VI. Summary and recommendations 17 (d) Synthetic-rubber paints 5 (e) Whitewash 5 VII. Appendix 19 2. Wall specimens 6 (a) General description 6 I. INTRODUCTION (b) New common brick 6 (c) Used common brick 6 Tests to determine the comparative durabil- (d) Cast concrete 6 ity of four general types of paints and one (e) Stone-concrete block 6 (f) Cinder-concrete block 6 whitewash applied under practical painting con- (g) Lightweight-aggregate-concrete block-_ 6 ditions to wall specimens of porous masonry (h) Cement-asbestos shingles 6 were conducted at the National Bureau of III. Painting the wall specimens 6 Standards in an out-of-door test field. The speci- 1. General procedure 6 mens were exposed to weathering conditions for (a) Preparation of the surface 7 (b) Mixing of paints 7 periods of from 24 to 33 months during the (c) Application of paints 7 years from 1940 to 1943. As the use of porous 2. Cemen(>water paints 7 masonry products has increased, so has the 3. Resin-emulsion paints 7 need for 4. Oil-base paints 7 more knowledge of water-repellent and 5. Synthetic-rubber paints 7 decorative finishes for such surfaces.. 6. Whitewash . 7 Permeability of masonry walls to water has IV. Painting the field office 7 been discussed in other reports of the Building V. Test results 9 Materials and Structures series.' This paper 1. Basis of evaluation 9 discusses the condition of specimens of porous (a) Appearance and durability 9 masonry after exposure to the weathering per- (b) General rating 9 (c) Reflectance 9 iod and reports the behavior of coatings of vari- (d) Spreading rate 10 ous types which were applied to these speci- 2. Paints 10 mens. (a) Cement-water paints 11 Masonry specimens, to which the (b) Resin-emulsion paints 11 paints (c) Oil-base paints 11 herein discussed were applied, were constructed (d) Synthetic-rubber paints 14 of new and used common brick; cast concrete; (e) Whitewash 15 3. Wall specimens 15 Building Matei'ials and Structures Reports BMS55, Effects of Wetting and Drying (a) Performance of coatings on commonly on the Permeability of Masonry Walls ; BMS76, Effect of Outdoor Exposure on the Water Permeability of painted surfaces 15 Masonry Walls ; BMS82. Water Permeability of Walls Built of (1) Stone-concrete block 15 Masonry Units; BMS94. Water Permeability and Weathering Re- Cinder-concrete block 15 sistance of Stucco-Faced. Gunite- Faced, and "Knap Concrete-Unit" (2) Walls ; and BMS95, Tests of Cement-Water Paints and Other (3) brick 16 New common Waterproofings for Unit-Masonry Walls. [1] — stone-, cinder-, and lightweight-aggregate-con- II. MATERIALS crete block ; and wood frame with cement-asbes- tos shingle facing. 1. Paints Paints used in the tests were of the types (a) Cement-ivater Paints commonly applied to masonry surfaces. They were white in color and included 20 cement- Cement-water paints are water-dilutable water paints, 4 resin-emulsion paints, 4 oil-base paints in which portland cement is the binder. paints, 5 synthetic-rubber paints, and 1 white- They are especiaUy suitable for use on porous wash. Some were proprietary brands while masonry walls that are damp at the time of others were experimental mixes.