Document Yjj9RpO50JqRZD1M049wk4kGN

BOY QUARTERLY DEVOTED TO PRACTICAL AND TECHNICAL DISCUSSIONS OF PROTECTIVE AND DECORATIVE PAINT COATINGS. BUILDING MATERIALS AND OTHER LEAD PRODUCTS Published and copyrighted by National Lead Company, in Broadway, New York, :V. Y. Vo l u me I 1923 Nu mb er 3 INDEX GUIDE Subject Standard Classification Nos., Page A.I.A. Die Ceating............................ 23 Influence of Color........... 22 25d3--Painted Decoration Piecing Pattern in Paint 20 25d3--Painted Decoration Light Paint for Ships' Bottoms............................ 24 Paint Under Riveted Joints.................................... 17 Red-lead for Priming Wood................................. 21 13e2--Painting Structural Steel 19a3--Lumber (Treat- Retarding Bacterial ments) \ Growth................................. 17 ........................................ 19 25c--Painting 29b8--Plumbing What is Shellac?.............. 21 25bll--Varnish Additional copies of the Dutch Bog Quarterly for (fling can promptly 6* secured by writing to address given above. Previous copies mag also be secured by request. Retarding Bacterial Growth -JESIwof paint's sterilizing power was recently *earrie3"out in the Institute of Industrial Re- iat Washington, D. C. On a laboratory wall ,of paint was applied to a small area. After ^dfjing^the painted surface and the unpainted Nsrea next; to it were lightly rubbed with a different fc^alS^hich.had been moistened with sterile water. in each swab was then squeezed out^into^pTates of agar sugar, a jelly-like mixture in which''germs easily multiply so that little masses of them may be seen on the top after the necessary time has elapsed. Examination showed that the plate made from the unpainted area contained a positive bacterial growth. The one made from the paint ed area: showed a negii- gible growth. The illus- iraticoshow the results Place I--Shoving abundant bacte- in both caso* r"` *ro'rth in culture frortl ur" painted section of wall. Then a culture of three species of germs each of a death-dealing type were mixed with a dry powder and blown upon the two surfaces--painted and unpainted. Similarly the germs in a sterile liquid were sprayed on other portions of the same surfaces. One hour later plates were made in the agar the same as before and the growths were positive tho not so pronounced from the painted areas. Next, the two surfaces were washed with soap and sterile water. Plates in agar were made an hour later. The agar containing the culture from the unpainted area showed abundant growth while -the culture from the painted area showed a very little. These tests strongly indicate that if a painted surface becomes contaminated the source of danger may be removed by washing and also that infected surfaces may be made sterile by painting. These results are probably not so much due to any germicidal properties which paint may possess, but to the fact that the old surface is covered with a clean washable film of paint. The danger of an unpainted dingy or rough wall is that it will retain moisture a long time and that its porous nature makes it easy for floating organic matter to collect. This kind of wall cannot be effectively washed so that the two factors necessary for quick bacteria growth--moisture and organic matter cannot be re moved. If a wall is cov ered with a good water proof coat of paint such as produced with white- lead-and-oil, its smooth surface is easily washed and need never afford a resting place for germs. That is why every inch " SfJSr efface in a hospital is section of wait. painted. Paint Under Riveted Joints 1ZING years of experience in mainlarge steel outdoor structures, an itly stated that the older structures : have proved to be seriously lacking was his principal point of criticism; the riveting fails to draw the component parts of the steel members into contact tight enough to prevent moisture entering and rust beginning and, cor