.%; ./ .: MIL-STD-81OC ./_ .+. Downloaded from https://www.everyspec.com (2) Synthetic materials - (a) PVC formulations (e.g. those plasticized with fatty acid esters). 4 (b) Certain polyurethane (e.g. polyestera and some polyethers). (c) Plastics, which contain organic fillers of laminating materials. (d) Paints and varnishes which contain susceptible constituents. b. Indirect attack on materials. Damage to fungus resistant from indirect attack when:
materials results’ (1) fungal growth on surface deposits of dust, grease, perspiration and other contaminants which find their way onto equipment during manufacture or accumulate during service can cause damage to the underlying material even though that material may be resistant to direct attack. (2) metabolic waste products (i.e. organic acida), excreted by fungi, cause corrosion of metals, etching of glass or staining or degrading of plastics and other materials. (3) the iroducta of fungal growth on adjacent materials, which are susceptible to direct attack, come in contact with the resistant materials. 1.3.2 Ybvsical interference. Physical interference can occur as follows: a.
Electrical or electronic systems. Damage to electrical or electronic ayst,emsmay result from either direct or indirect attack. Fungal growth can form undesirable electrical conducting paths acrosa insulating materials or may adversely affect the electrical characteristics of critically adjuated electronic circuits. b. Optical systems. Damage to optical systems results primarily from indirect attack. The fungal growth can adversely affect light transmission through the optical system; block delicate moving parts; and change non-wetting surfaces to wetting surfaces with resulting loss in performance. 1.3.3 Health and aesthetic factors.
Fungus growth on equipment can cause physiological problems, (e.g. allergies) or be so aesthetically unpleasant that the users will be reluctant to use the equipment. 1.4 .GUIDLIN E ES FOR DETERMIMG TEST PROCEDURES AND TEST CONDITIONs. Since microbial deterioration is a function of temperature and humidity and ia an inseparable condition of hot-humid tropics and the midlatitudea, it must be considered in the design of all standard general purpose materiel.1 Method 508.2 (Fungus) consequently Is used Wkm an item iS to be tested tO determine if fungus growth will occur and if so, how it wI1.1affect the use of the item.
lFrom AR 70-38, Research, Development, Teat and EvaluatlOn Extreme Climatic Conditions, Chapter 2, Climatic Criteria. of Material for METHOD 508.2 508.2-2