Sodium Pyrithione is an effective and high active broad-spectrum antimicrobial preservative that acts against moulds, yeasts,bacteria and algae. Generally by conventional methods, fungi (yeast and mold) are not easily detected as the filamentous mycelial forms of mold tend to accumulate in machine crevices, in piping, on sump walls, gear boxes and other solid surfaces. Besides this accumulation occurs over damp walls and partition boards, Attempts to completely eliminate bacteria using bactericides alone result in conditions that influence the growth of fungi. Thus heavy fungal contamination may require both mechanical and chemical treatment.
Chemical stability : Sodium Pyrithione is stable under normal environmental conditions if stored in closed, dark containers. Even alkalinity of metal working fluids is not affected by the addition of Sodium pyrithione.
Compatibility: Compatible with most raw materials used in technical applications.
Antimicrobial Activity: To control fungi very small doses of Sodium Pyrithione is required. Studies indicate that Sodium Pyrithione can effectively control bacteria in semisynthetic and synthetic metalworking fluids even at a minimum dose of 1000 ppm. Other major applications include as an anti-fungal additive in Gypsum board panels, as preservative in Lyophilised Human Plasma etc.Different use and contamination conditions require different levels of Sodium Pyrithione. Although it is compatible with most ingredients, both physical and chemical compatibility testing is usually recommended.
Need for Mould Control: Moulds are infestation on various bio-substrates which tend to affect the physical structure and characteristics. We need to often review the nature of the infestation and protect it in time before it strikes the Leather and Leather goods.
Mould and mildew thrive in warm, dark, damp conditions. They penetrate deep into the fibre of the leather which can weaken them and cause permanent damage. Be aware that if leather is poorly stored mould and mildew can grow very quickly. Mould and mildew penetrate leather to its core and so are impossible to remove entirely. However, spores will remain dormant if the correct preventative measures are taken.
Known Facts: All molds are fungi, but not all fungi are molds. Mold and mildew represent a very simple life form which are unable to perform photosynthesis in the usual manner. Both represent the same thing. The Nutrients in organic materials are digested by Molds using the available enzymes in the substrates like Leather. Moulds are a special grades of fungi. The beginning is in the form of a single spore which visible only through a microscope. Spores are transmitted by wind or by insects. When a spore lands on a suitable substrate like leather, it begins to germinate. The spore first breaks open to send out a tiny thread called the hypha. This hypha grows down into the leather, by soaking up food , and dividing into many different hyphae. The leather ultimately becomes filled with mould hyphae. Next is the reproduction phase. The mould transmits hypha into the air, which divides many times, producing many spores. With thousands of these substrates, millions of spores are grown, ready to be carried to a new site by wind or insects
Characteristics of a Mould: Initially as mould grows into leather, usually no major damage is caused. The mould soaks up its food from the parts of the leather that do not contribute to strength. Moulds impart colour-staining, grain marks and leave spots which makes the finished leather look inferior causing downgrading of the finished product. This can be expensive. Once moulds are inside the leather, simply cleaning the surface will not solve the problem, since the moulds will grow right out again. Moulds can devour important additives used in leather making, such as fat liquors, tannins and so on
What do Moulds need to grow: Water. Allowing leather to get wet will encourage mould growth. Leather in the wet blue state is highly prone to mould growth. Acidity. Slightly acidic environment allows Mould to grow best. Pickled pelts are too acid for fast mould growth. Very alkaline conditions do not support much mould growth. Warmth. Typical room temperatures between 25-30 deg C is very ideal for Mould growth. Summer temperatures are very conducive so are tropical weather. Leather stored in cool conditions will slow down the growth effectively. Oxygen. If wet blues or pickled pelts are baled and pressed into a tightly packed state, mould will only grow on the outside. There is too little oxygen inside the pack to aid growth. Nutrients. Moulds soak up the soluble parts of leather as food. Unfortunately, we cannot remove these to control mould growth. Some leathers (like vegetable tanned leathers) have more nutrients, and support especially vigorous mould growth.
Why do Fungicide Fail: fungicide does not control a problem mould that appears in the Tannery concentration is too low to control a problem mould. fungicide formulation is unstable stage of application is not appropriate fungicide loses activity due to interaction with process components: oxidising or reducing agents, alkalies or acids, greases. fungicide is ineffective on splits due to poor penetration or reasons above.
When Mould protection has failed: Rather than increase fungicide concentration, it is usually best to immediately change to, or add, a different active ingredient. The characteristics of the ingredients must provide suitable and long standing protection. Usually this can be assesed by the MIC of the ingredient which will provide the best protection.
Criteria for Fungicide Selection: Some moulds are resistant to certain types of fungicide. TCMTB for example is not effective against Trichoderma viride, which can be brought into the tannery on the wooden pallets, Amorphotheca resinae, on the other hand, are resistant to phenolics. Selection of a suitable fungicide requires consideration of the material to which it is to be applied and the conditions under which the material is to be stored. Tanners should liaise closely with their fungicide suppliers to ensure both optimum selection and application conditions as well as ensuring that the fungicides are handled with due regard to health and safety, i.e. using appropriate personal protective equipment.
