Mould staining

To establish that inhibitor addition had no deleterious effect on resin properties the glass transition temperature, moisture permeability, and adhesion properties of the two part liquid resin with and without inhibitor was determined and in no cases were significant changes in properties observed. Technically important factors were also determined for transfer moulding resins i.e. mould staining and spiral flow again no serious detrimental effects were observed. 

Microbicides are used in the textile industry to effectively prevent mould stains and rotting in textiles and also to prevent textile auxiliaries from decomposition and mould formation. 

Reduced mould staining due to the introduction of higher purity and synthetic release systems. 

Basic materials such as lime or magnesium oxide increase the hardening rate of novolak-hexa compositions and are sometimes referred to as accelerators. They also function as neutralising agents for free phenols and other acidic bodies which cause sticking to, and staining of, moulds and compounding equipment. Such basic substances also act as hardeners for resol-based compositions. 

The principal application of melamine-formaldehyde moulding compositions is for the manufacture of tableware, largely because of their wide colour range, surface hardness and stain resistance. The stain resistance does, however, leave something to be desired and one aim of current research is to discover alternative materials superior in this respect. Cellulose-filled compositions also find a small outlet for trays, clock cases and radio cabinets and other purposes. The mineral-filled powders are used in electrical applications and knobs and handles for kitchen utensils. 

A few studies have been performed examining the resistance of acetylated wood to mould and stain fungi in a laboratory environment (Wakeling etal., 1991, 1992). These studies found that acetylation reduced the rate of mould growth, but at the end of the test there was no difference in the extent of colonization. Furthermore, samples modified to a WPG of 10 % exhibited a higher rate of colonization for reasons that were not clear. Samples acetylated up to a WPG of 20 % did not exhibit any improvement in performance in terms of mould growth, compared to unmodified samples, when exposed in a field trial. 

Wakeling, A.N., Plackett, D.V. and Cronshaw, D.R. (1991). The susceptibility of acetylated Pinus radiata to mould and stain fungi. In Proceedings of the International Symposium on Chemical Modification of Wood, Kyoto, Japan, Takahashi, M. (Ed.), pp. 142-147. 

Pentachlorophenol and its salt, sodium pentachlorophenate, are used primarily as wood preservatives on telephone poles, pilings and fence posts. In Europe, pentachlorophenol and its derivatives, sodium pentachlorophenate and pentachlorophenyl laurate are used to control sap stain in green lumber. It is also used in Europe on millwork to prevent the growth of mould and fungi, and as a preservative for waterproof materials (i.e., tarpaulins) that are used in outdoor applications. In the United States, it is used almost entirely for treatment of utility poles (Agency for Toxic Substances and Disease Registry, 1994). 

Prevention of Stain and Mould in Lumber and Board Products... 

Planing air-dried lumber largely removes surface discoloration caused by moulds, but discoloration in the wood caused by staining fungi cannot be removed. 

A similar test involves immersing the moulding in an acid fuchsin stain solution, followed by rinsing under tap water, when the degree of uniformity in treatment can be established by a visual examination of the intensity of the stain and by comparison with a standard that has been treated to a known level. 

This is part 19 of a series of articles designed to help injection moulders understand how a few analytical tools can help diagnose a part failure problem. It deals with the particular case of exterior parts moulded from flexible PVC that developed black stains after a relatively short period of time exposed to the elements. Full details of the problem and the solution are presented. 

Figure 25.7 TEM of rubber-modified (36%) injection moulded S/DPE(15) (a) MSP 1, (b) MSP 2, and (c) MSP 3. Cryo ultra thin sections stained with Ru04...

Figure 25.8 TEM of 36 % MSP 1 rubber, mixed in S/DPE(30) and injection moulded. Cryo ultra thin section stained with RUO4...

S. chartarum. Here, air samples on culture media showed negative results even on cellulose-based nutrient agar, while microscopy yielded 7,500 spores of S. chartarum per cubic meter [20]. Additionally special staining techniques allow differentiation between the sum of all bacteria or mould spores from active ones [21]. 

Sulphurous Add. This acid is used to bleach silks, woolens, (see No, 1716), and to remove vegetable stains and iron-moulds from linen. For these purposes it is prepared from sawdust, or any other refuse carbonaceous matter. The salts fonned by the combination of sulphurous acid with a base are called sttlphitbs. (See Nos, 1717 and 1718.)... 

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