5.3.3 Cleaning and Carrier Restoration

5.3.3.1 LPs should be handled very carefully, never allowing fingers to touch the groove area of any vinyl disc. Sweat and other skin borne deposits may in themselves cause replay noise, however they will also attract and adhere dust to the surface and enable the growth of moulds and fungi increasing replay noise. Cotton gloves should be worn when handling discs. If appropriate gloves are not practical, discs should be withdrawn from (and replaced in) their sleeves in a manner that ensures the finger tips are placed on the label area and the base of the thumb at the edge, leaving the groove area untouched.

5.3.3.2 Dust, the enemy of all sound recordings, is a major problem with LPs for two reasons. The finer groove means dust particles are comparable in size with the stylus and cause clicks and pops. The electrostatic nature of vinyl increases the attraction of dust to the surface of the disc.Various commercial devices have been developed in an attempt to neutralise these static charges, from carbon-fibre brushes to piezo-electric ‘guns’ that ‘fire’ a neutralizing charge at the record surface, all of which are effective to varying degrees.

5.3.3.3 The most effective way of cleaning records is to wash them. Cleaning machines, such as the well known Keith Monks machine, coat the surface with a cleansing fluid which is then removed by a tracking suction device which moves across the surface to suck up both the fluid and any dust or dirt in the grooves. A simpler method is washing, avoiding the label area, with demineralised water and a mild detergent or non-ionic wetting agent such as diluted (1 per cent) Cetrimide (n-cetyl pyridinium chloride) which has anti-fungal and anti- bacterial properties. The disc may then be brushed in a circular motion with a soft camel hair paint brush, again avoiding the label area, and rinsing off, once more using distilled water. Greasy deposits on vinyl discs may be removed with isopropyl alcohol. As non-vinyl discs may be affected by alcohol, care should be taken to ensure that the solvent does not cause damage to the disc.

5.3.3.4 Record cleaning solutions which do not disclose their chemical composition should not be used. All decisions about the use of solvents and other cleaning solutions should only be made by the archivist in consultation with the appropriate technical advice by qualified plastics conservators or chemists.

5.3.3.5 As with historical mechanical and other obsolete formats (see 5.2.3 Cleaning and Carrier Restoration), ultrasonic cleaning may be effective. Care should be taken in the selection of solvent, though a 1 per cent solution of Cetrimide in distilled water is an appropriate cleaning solution. The label should be kept clear of the fluid, and the disc rotated slowly until the whole groove area has been wetted.

5.3.3.6 Perhaps the most effective method of reducing the effects of dirt, dust, and static charge is to play the records wet. This may be achieved by simply covering the disc with a Cetrimide solution, or by tracking a soft wet brush ahead of the stylus.Wetting the record can dramatically reduce the incidence of clicks and pops, however, it has the effect of increasing surface noise in all subsequent ‘dry’ plays. Wet playing using liquids containing alcohol is not recommended as the polymer bearings of cantilevers may chemically react with negative results.

5.3.3.7 The most frequently needed restoration of a disc recording is flattening. The following approach applies whether the disc is dish-shaped or bent. A thermostatic oven (a laboratory style oven is mandatory, a domestic oven is not appropriate) is required at a setting usually not exceeding 55º C and provided with two very clean sheets of hardened and polished glass, thickness 7 mm, 350 mm square. After hand cleaning and drying the record it is placed on the pre-heated bottom sheet in the oven and the top sheet is suspended in the oven. After ca. half an hour the record is inspected and may well have sunk to a flat position. If not, the elasticity is tested as an indication of softening, and experience will tell if placing the hot top plate on the record might have the desired effect. The sandwich is left for half an hour, and the top sheet is lifted using gloves. If the record is perfectly flat, the complete sandwich is removed from the oven and left to cool on an insulating support. If flattening has not been obtained, the temperature is raised in 5º C intervals and the procedure repeated. Never apply the flattening force unless the softening is sufficient.

5.3.3.8 Flattening discs is a useful process because it can make unplayable discs playable; however, current research into the procedure of flattening discs with heat shows that it causes a measurable rise in subsonic frequencies, and even in the low audible frequency range (Enke 2007). Though the research is not conclusive the point should be noted in determining whether to flatten a particular disc. The analysis of the affect of flattening was carried out on vinyl discs but the range of tests were not extensive and further research is required. The possibility of such damage should be weighed against the benefit of enabling the playing of the disc.