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This article first appeared in Conservation News 73. AeroglymTM or not AeroglymTM: that is the question!In recent years I have become aware of an increase in the use of Aeroglym for cleaning shellac, lacquer, shell, ivory, marble and ceramics with pleasing results. Aeroglym was developed for the aerospace industry as a cleaner for "plastics and acrylics". This article is not questioning the quality of Aeroglym or its efficiency to do what it was designed for. My aim is to describe its constituents, how it works and what possible effects it may have on objects. The information is based purely on the ingredients listed on the data sheet and on one phone call to the company. It will be for readers to draw their own conclusions about the efficiency and effect of using Aeroglym based on their experience and academic knowledge.IngredientsAccording to the product's general information sheet, Aeroglym is "free from abrasives, silicones, solvents and VOCs" (Volatile Organic Compounds). The company safety data sheet specifies that the product is a "water-in-oil emulsion". This is a two phase system, i.e. an emulsion which contains two liquid phases. In this instance the globules of water (internal phase or dispersed) are surrounded by globules of oil (external or continuous phase) (Dictionary of Applied Science). The oil is referred to as mineral oil (petroleum solvent) of a non-drying nature; the oil is not specified and I was unable to obtain the name of the exact oil from the company. I assume that it is likely to be paraffin oil. This oil is often used in polishes (Mayer 1981) and many other products including cosmetics and medicines.In order for water and oil to co-exist in an emulsion, an emulsifier is required to confer permanence and stability to the emulsion. The emulsifier is likely to be potassium silicate referred to in the data sheet along with aluminium silicate. Potassium silicate may be present as solid or in solution. In solution, potassium silicate acts as an emulsifier or catalyst (Dictionary of Chemistry). The aluminium silicate, which is not water soluble, would be suspended and subsequently during application would act as a mild abrasive. The final ingredient listed is indicated by the mild lavender odour. Lavender oil is classified as an essential oil (ester) extracted from the flower, not from the stems, as is the case for spike of lavender. The oil has similar properties to turpentine and is also a powerful solvent for resins. It is slower drying than turpentine and leaves behind a resinous material (Doerner, 1937). I can only assume that lavender oil is used to impart a pleasant odour to the product, and impart a greenish cast to the solution. It must be remembered that lavender oil is not specified in the data sheet, and there are no other ingredients listed. Application and resultsThe viscous paste is applied with a soft cloth or cotton wool, and is then left for a short while to allow the water to evaporate, leaving an oil and silicate sludge on the surface. This is then buffed off to produce a pleasing sheen, similar to that of furniture burnishing creams or a light waxing. The sheen is the result of oil and silicates acting like a grain filler on an uneven surface. It may also be left under metal fittings, cracks, splits, small fissures etc. This residue is not only a particulate but is bound in lavender oil and paraffin oil. If this is allowed to pool due to excess use, or poor application techniques it may attract dust, or penetrate into the substrate. Lavender oil will gum and darken in time, which may cause alligatoring. This defect may also occur if lavender oil mixes with another drying oil like linseed oil, according to Knut Nicolaus. There are many references in furniture restoration literature that encourage the use of linseed oil for various purposes. It is therefore likely that linseed oil residue could be present, thus making subsequent treatment difficult. In the past, continued cleaning with similar emulsions to this one and those designed for cleaning copper alloys etc. have resulted in the unsightly build-up of solid material which is difficult to remove. During a phone call to the company's technical advisor he admitted that there would be a residue although he thought that it would not be a problem. He also said that he would not use it for anything other than what it was designed for, and he would not use it on furniture.ConclusionAs conservators/ restorers in practice or training our responsibility is to preserve artefacts. This requires not only practical work but also a good understanding of materials and processes. Data sheets are useful, but they can only give you an idea of the constituents rather than the whole picture. Further research is needed before this product is accepted as a good cleaner. It may produce a pleasing appearance and be simple to use, but everything comes at a price: the object may become difficult to treat again without serious intervention, on the other hand it may be the case that any residue is not and will not be a problem. This may be a first! It is not good practice to rely entirely on manufacturers' data sheets without looking at the possible effects that the material may have on an object. If anyone has any experience In using this product, good or bad, or has an alternative then please contact the Section.
AcknowledgementWith thanks to Leslie Charteris.References
SupplierAeroglymTM manufactured by AeroglymTM.Letchworth, England. Tel: 01462 677766 Fax: 01462 677712 |