TY - JOUR

T1 - Melaminharzimprägniertes sowie mit Wetterschutzlasur oberflächenbehandeltes und unbehandeltes Vollholz während zweijähriger Freilandbewitterung

AU - Rapp, A. O.

AU - Peek, R. D.

PY - 1999/10

Y1 - 1999/10

N2 - Samples of solid wood, impregnated with melamine resin or coated with varnish, as well as untreated Scots pine sapwood (Pinus sylvestris L.), Norway spruce (Picea abies L.), English oak heartwood (Quercus robur L.) and Douglas fir heartwood (Pseudotsuga menziesii Franco.) were exposed to natural weathering without ground contact for two years. The melamine resin even in low concentrations provided distinctive protection against photochemical wood degradation by weathering and infestation by wood staining fungi, but did not protect against cracking and high moisture content. In the second year of natural weathering the samples exceeded 25% moisture content on 9 days (untreated Douglas fir), 21 days (untreated oak), 88 days (untreated spruce), 129 to 160 days (pine impregnated with MF resin), 166 days (untreated pine) and 236 days (pine with varnish). After two years of weathering, the samples treated with biocide-free, transparent varnish gained a moisture content of 130% within 1 hour of floating in water. Light microscopy revealed extensive bacterial colonisation in the interior of the varnished samples which is made responsible for the increased water adsorption. The varnish, which was perforated in numerous places by blue stain but nevertheless still restricted diffusion, induced long-lasting periods of high moisture content. Thus the conditions necessary for the growth of bacteria and soft rot were provided and the risk of decay increased by the damaged coating.

AB - Samples of solid wood, impregnated with melamine resin or coated with varnish, as well as untreated Scots pine sapwood (Pinus sylvestris L.), Norway spruce (Picea abies L.), English oak heartwood (Quercus robur L.) and Douglas fir heartwood (Pseudotsuga menziesii Franco.) were exposed to natural weathering without ground contact for two years. The melamine resin even in low concentrations provided distinctive protection against photochemical wood degradation by weathering and infestation by wood staining fungi, but did not protect against cracking and high moisture content. In the second year of natural weathering the samples exceeded 25% moisture content on 9 days (untreated Douglas fir), 21 days (untreated oak), 88 days (untreated spruce), 129 to 160 days (pine impregnated with MF resin), 166 days (untreated pine) and 236 days (pine with varnish). After two years of weathering, the samples treated with biocide-free, transparent varnish gained a moisture content of 130% within 1 hour of floating in water. Light microscopy revealed extensive bacterial colonisation in the interior of the varnished samples which is made responsible for the increased water adsorption. The varnish, which was perforated in numerous places by blue stain but nevertheless still restricted diffusion, induced long-lasting periods of high moisture content. Thus the conditions necessary for the growth of bacteria and soft rot were provided and the risk of decay increased by the damaged coating.

UR - http://www.scopus.com/inward/record.url?scp=0033215855&partnerID=8YFLogxK

U2 - 10.1007/s001070050353

DO - 10.1007/s001070050353

M3 - Artikel

AN - SCOPUS:0033215855

VL - 57

SP - 331

EP - 339

JO - Holz als Roh - und Werkstoff

JF - Holz als Roh - und Werkstoff

SN - 0018-3768

IS - 5

ER -