White oil is an insecticide spray used for controlling a wide range of insect pests in the garden. The spray works by blocking the breathing pores of insects, causing suffocation and death. It is effective in the control of aphids, scale, mealybug, mites, citrus leafminer and other smooth skinned caterpillars. [1] "White oil" is also an alternative name for mineral oil. [2] Technical white oils are colourless oils derived from non-carcinogenic light base oils (LBOs) and are further refined (by hydrogenation or acid treatment) to achieve extremely low levels of aromatics, but they do not meet the stricter levels required by pharmacopeia monographs.
Pharmaceutical white oils, by contrast, are derived from technical white oils, and then undergo a second-stage hydrogenation or acid treatment to achieve ultra-low aromatics and other impurities, in order to comply with the specifications set forth in international pharmacopeia monographs (for example for use in pharmaceutical, cosmetic or food-contact applications).
White oil is sold commercially as a petroleum oil-based organic pesticide, in both a concentrate, [3] [4] [5] and ready-to-use spray bottle or can. [6] [7]
The term "horticultural oil" may be used to differentiate this petroleum oil-based product from homemade products using vegetable oil. [8]
The quantities vary depending on the source, but a common concentrate typical mixture is 4 parts of vegetable oil (a non-mineral oil) to one part of liquid dish-washing soap/detergent (for washing by hand). [9] [10] [11] It may be blended in a mixer or shaken by hand in a jar or bottle until homogeneous to be stored. [12]
Concentrates must be diluted before use at a ratio of 10–20 ml concentrate per litre of water and placed in a spray bottle or sprayer. [13] [10] [9] As with ready-to-use spray bottles or cans, the mixture is applied to all surfaces of a plant's leaves and stems. [8] [9] [10] [11]
All sources note that white oil should not be applied when temperatures above 25–30°C are expected, as this may cause the plant to "burn". [8] [9] [10] [11] [13]
Industrial and Specialty Applications ===
White oils are used across a wide range of industries as plasticisers, processing aids, lubricants, and carrier fluids due to their purity, stability, and low aromatic content.
'''Rubber industry:''' Mineral oils are commonly used as plasticisers and processing aids during the manufacture of elastomer compounds. The oil requirement varies according to the polymer type. For instance, Styrene–Butadiene Rubber (SBR), which is widely used in passenger car tyres, requires oils with a relatively high aromatic content to improve rolling resistance, wet grip, and abrasion properties. In contrast, non-polar rubbers such as Ethylene–Propylene–Diene Monomer (EPDM) demand oils with very low aromatic content.
'''Thermoplastic elastomers and polymer applications:''' Two important types of thermoplastic elastomers that use mineral oil in high quantity are styrene block-polymers (TPE-S) and poly-olefins (TPE-O). These require mineral oils with extremely low aromatic carbon content as plasticisers. Higher aromatic content can affect the styrene domain of TPE-S and reduce mechanical performance, particularly at elevated temperatures. For applications requiring UV stability or food contact compliance, pharmaceutical-grade white oils are preferred. Mineral oils are also used to produce moulding aids for plastic parts.
'''Adhesives:''' Many pressure-sensitive hot-melt adhesives (HMPSA), especially those based on SBR, contain significant quantities of highly refined mineral oil. Selecting the proper oil grade helps prevent migration of components from the adhesive through packaging materials and into food.
'''Cosmetics and pharmaceuticals:''' In cosmetic and pharmaceutical products, only highly refined white oils are used. These are required to meet additional purity and safety specifications defined by international pharmacopeias (such as the USP, BP, and EP) and regulations like those of the U.S. Food and Drug Administration (FDA).
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