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Exterior durability : III / Zeno W. Wicks in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 71, N° 890 (03/1999)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 71, N° 890 (03/1999) . - p. 31-33 Titre : Exterior durability : III Type de document : texte imprimé Auteurs : Zeno W. Wicks, Auteur ; Frank N. Jones, Auteur ; S. Peter Pappas, Auteur Année de publication : 1999 Article en page(s) : p. 31-33 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Climat Durée de vie (Ingénierie) Revêtements -- Détérioration Index. décimale : 667.9 Revêtements et enduits Résumé : Exterior durability of coatings refers to their resistance to change during outdoor exposure ; such changes include changes of modulus, loss of strength, embrittlement, discoloration loss of adhesion, chalking, loss of gloss, and environmental etching. Thus, both aesthetic and functional properties are involved. The terms outdoor durability and weatherability are also used. This series examines exterior durability, focusing onthe most common chemical processes leading to degradation of coatings - photoinitiated oxidation and hydrolysis resulting from exposure to sunlight, air, and water. These processes are interrelated, including enhanced photoxidative degradation in high humidity and enhanced hydrolytic degradation during photoexposure. Furthermore, both processes are accelerated by higher temperatures. Hydrolytic degradation may be enhanced by exposure to acid, as from acid rain. Other atmospheric degradants include ozone and oxides of nitrogen and sulfur. Changes in temperature and humidity may result in cracking, which arises from the expansion and contraction of coatings or substrates. Rates at which these processes occur vary, depending on exposure site(s), time of year, coating composition, and substrate. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18024 [article]

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Parameters influencing the spray behavior of waterborne coatings / Lin-lin Xing in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 71, N° 890 (03/1999)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 71, N° 890 (03/1999) . - p. 37-50 Titre : Parameters influencing the spray behavior of waterborne coatings Type de document : texte imprimé Auteurs : Lin-lin Xing, Auteur ; J. Edward Glass, Auteur ; Raymond H. Fernando, Auteur Année de publication : 1999 Article en page(s) : p. 37-50 Note générale : bibliogr. Langues : Américain (ame) Catégories : Cisaillement (mécanique) Dépôt par pulvérisation Gouttelettes Latex Revêtements en phase aqueuse:Peinture en phase aqueuse Rhéologie Système de pulvérisation (technologie) Viscosité Index. décimale : 667.9 Revêtements et enduits Résumé : The influence of liquid pressures and orifice diameters on the sprayability of non-Newtonian, waterborne latex coatings, that vary in latex particle size and thickener composition are examined in this study. It is observed that the higher the dynamic uniaxial extensional viscosities (DUEVs, ηe) of the coatings, the larger the Sauter mean diameters (SMDs) of the spray droplets and the broader the droplet size distributions. The shear viscosities at high shear rates and the parameter reflecting shear elasticity, the storage moduli, at low deformation rates do not correlate with the droplet sizes and the distributions observed. In addition to these observations, the Sauter mean diameters of spray droplets decrease with increasing spray pressures and with decreasing orifice diameters; however, with increasing pressures, pulsations in the fluid due to turbulence create areas of high and low droplet density.The relationship of the SMD to orifice diameters using fan nozzles is defined by the relationship:[FORMULA]The experimental results associated with each of these parameters are discussed in the text. Note de contenu : - EXPERIMENTAL SECTION : Formulation of latex coatings - Airless spray process - Measurement of droplet size and their distribution in spray coatings - Rheology measurements - RESULTS AND DISCUSSION : The effect of orifice diameters on SMDs of spray droplets - Derivation of parameter dependent equation for latex coatings sprayed by airless equipment through fan nozzles Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18025 [article]

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Quantitative method for determination of thickener equilibration in coatings / Greg D. Shay in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 71, N° 890 (03/1999)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 71, N° 890 (03/1999) . - p. 51-59 Titre : Quantitative method for determination of thickener equilibration in coatings Type de document : texte imprimé Auteurs : Greg D. Shay, Auteur ; Keith R. Olesen, Auteur ; David L. Hardman, Auteur Année de publication : 1999 Article en page(s) : p. 51-59 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Epaississants Formulation (Génie chimique) Mélanges (chimie) Revêtements en phase aqueuse -- Additifs:Peinture en phase aqueuse -- Additifs Rhéologie Viscosimétrie Index. décimale : 667.9 Revêtements et enduits Résumé : A quantitative method for the determination of thickener incorporation rates and thickener equilibration times (TET) in coatings has been developed using a digital Krebs viscometer. Upon adding thickener to a coating sample, the viscometer simultaneously provides viscosity readout and continuous mixing at constant speed with degree of agitation simulating the relatively poor mixing conditions observed in some paint production equipment near the end of the process cycle. By plotting viscosity as a function of mixing time on the instrument, rates of incorporation and equilibration were obtained. The method proved to be reliable and generally reproducible in limited testing with apparent applicability to a variety of thickener types in both aqueous solution and in actual latex coating formulations. Meaningful comparisons of incorporation are now possible to facilitate appropriate thickener selection and to provide insight regarding optimal modes of incorporation or orders of addition for process cycle time reduction. Note de contenu : - INTRODUCTION : Thickener types and incorporation options - Thickener equilibration - EXPERIMENTAL : Detailed procedure for aqueous solutions - Detailed processus for pigmented coatings - RESULTS AND DISCUSSION : Effect of thickener concentration in paint - Effect of temperature - Procedure repeatability in aqueous solution - Effect of thickener addition rate - Effect of thickener type in aqueous solution - Instrument and viscosity stability in aqueous solution - Effect of thickener type in pigmented coatings - Effect of thickener dilution in paint - Effect of base addition order in a HASE thickener Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18029 [article]

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Changing nature of wood products - What does it mean for coatings and finish performance / Charles Jourdain in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 71, N° 890 (03/1999)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 71, N° 890 (03/1999) . - p. 61-66 Titre : Changing nature of wood products - What does it mean for coatings and finish performance Type de document : texte imprimé Auteurs : Charles Jourdain, Auteur ; Jack Dwyer, Auteur ; Keith Kersell, Auteur ; Douglas Mall, Auteur ; Ken McClelland, Auteur ; Robert Springate, Auteur ; Sam Williams, Auteur Année de publication : 1999 Article en page(s) : p. 61-66 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Assemblages (technologie) Composites Panneaux de fibres Panneaux de particules Revêtements:Peinture Index. décimale : 667.9 Revêtements et enduits Résumé : As the fundamental nature of North American forest has changed over the past 200 years, so have the properties of the building products derived from those forests. Smaller diameter secondand third growth trees yield lumber with higher percentages of knots and sapwood and less of the clear fine grain lumber traditionally used for architectural applications. Many of the current recommendations for finishing exterior wood products are based upon dated information. The more knotty solid wood products used today may have coarser grain and be predominantly flat-grained. Flat-grained lumber is more prone to grain raising and dimensional change. Saw-textured surfaces decrease the potential for grain raising and they enhance finish performance. Saw-textured knotty flat-grained wood products may perform better if they are finished with penetrating finishes (semitransparent stain) rather than with film-forming finishes (paints). Semitransparent stains and other types of penetrating finishes do not peel and tend to be less likely to show knot or extractives bleed. Film-forming finishes may also be used on knotty saw-textured flat-grained surfaces, however discoloration because of bleed-through at the knots continues to be a challenge, particularly with light-colored finishes. Use of different wood species, flat-grained knotty wood, and composites may require some changes in finishing practice and more careful selection of products for specific uses. For example, if a white painted look is desired, it may be better to use a paper-overlaid product to eliminate problems with knot bleed than to try to seal the knots using shellac. If finger-jointed lumber is used, extra care may be required to assure that the finish can adequately block the extractives. Sealing and painting the edges of composites is necessary to assure good performance. Paper-overlaid products give a good surface for painting. Advances in finger-jointing and factory prefinishing will add to the performance of modern wood products. In the coming decade, the transition to lumber from rapidly grown intensively managed forests will continue. New species and composites will become more available in the marketplace. Much of the burden for assuring the compatibility of finishes with new wood products will probably rest with the woatings manufacturers and their suppliers. The technology of paints and other finishes and the protocols for testing finishes must advance to keep pace with the changes in the substrates. Note de contenu : - WOOD PROPERTIES - EXTERIOR WOOD PRODUCTS : Architectural products and species - Imported wood species - Silvicultural practices to enhance wood quality - Lumber grades and quality - Flat-grained siding and lumber-effect on finishing - Wood/wood composites - Wood/plastic composites - Paper-overlaid products - Fiberboard - PAINTING GUIDELINES : Flat-grained solid lumber and siding - Finger-jointed lumber and siding - Plywood - Wood/wood composites - Wood/plastic composites - Paper-overlaid products - Fiberboard - Factory priming and finishing En ligne : http://www.fpl.fs.fed.us/documnts/pdf1999/jourd99a.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18038 [article]

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Mildew and mildew control for wood surfaces / Steve Bussjaeger in JOURNAL OF COATINGS TECHNOLOGY (JCT), Vol. 71, N° 890 (03/1999)

[article]  inJOURNAL OF COATINGS TECHNOLOGY (JCT) > Vol. 71, N° 890 (03/1999) . - p. 67-69 Titre : Mildew and mildew control for wood surfaces Type de document : texte imprimé Auteurs : Steve Bussjaeger, Auteur ; George Daisey, Auteur ; R. Simmons, Auteur ; Saul Spindel, Auteur ; Sam Williams, Auteur Année de publication : 1999 Article en page(s) : p. 67-69 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Additifs Antifongiques Biodégradation Bois Champignons et constituants Revêtements -- Détérioration:Peinture -- Détérioration Thallophytes Index. décimale : 667.9 Revêtements et enduits Résumé : Mildew growth is an ongoing problem. Fungal spores land on surfaces and, under the right environmental conditions, grow. Ideal conditions are warm, moist climates, oxygen, and a substrate that serves as a nutrient source for mildew.Mildew growth on finishes causes discoloration and premature failure of the finish. Prevention of mildew can be done by pretreating the wood with a preservative that contains a mildewcide. Removal of mildew is achieved by using appropriate cleaning solutions. Finishes that contain synthetic mildewcides, with or without zinc oxide, help the finish resist mildew growth. Note de contenu : - WHAT IS MILDEW : Definition - Effect on appearance and performance - Common species - Necessary contributing factors - Geographically prone areas - MILDEW CONTROL : Surface preparation - Mildewcides - Pretreatments and preservatives - ADVANTAGES OF MILDEWCIDES - DISADVANTAGES OF "POINT-OF-PURCHASE" MILDEWCIDES Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=18039 [article]

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