Experimental conditions

1. Method applied for measuring the properties of the sample oils

The following methods were applied to measure the properties of the sample oils. Emulsified sample oil ("mouse" formed) was measured after placing it on filter paper and removing the free water.

(1)Viscosity	Used a revolving viscometer (Tokyo Instruments, Model E viscometer). The measuring temperature was 15℃, but 40℃ for high pour point crude oil.
(2)Water Content	Measured according to JIS K2275 "Testing Methods for water Content of Crude Oil and Petroleum Products, 4. Distillation method.
(3)Density	Used a oscillating type density meter (Model DMA-48) made by Anton Paar Inc. The measuring temperature was 15℃, but 40℃ for high pour point crude oil.
(4)Evaporation rate	A Shimazu Model GC-17A capillary gas chromatograph was used to take measurements by the following method: Prepare some crude oils that evaporation rate is already known. Dilute them with carbon disulfide, and inject them into a gas chromatograph to take ther chromatograms. OV-101 was packed in the gas chromatograph's sample injector to hold inorganic substances and heavy components of crude oil. Use n-C20H44 as a reference to find the relative area of each lower normal paraffin than n-C20H44. The relationship between the sum of the above relative areas and the evaporation rate is used to make a calibration curve. Evaporation rate is obtained using this calibration curve.

2. Conditions of the circulating water channel experiments.

2 types of waves were used for this experiment: corresponding to wave ranks, "1" (referred to as "weak waves" throughout the rest of this paper) and "2" (referred to as "strong waves" throughout the rest of this paper), authorized by the Japan Meteorological Agency.
The temperature of the sea water was set to 25℃ in summer and 10℃ in winter. The test conditions for this circulating water channel experiment are shown in Table 2. (Circulating water channel

Table２ Conditions of the circulating water channel experiments.

Test conditions		Case1 (Summer) weak waves	Case2 (Summer) strong waves	Case3 (Winter) weak waves	Case4 (Winter) strong waves	Case5 (autumn) weak waves
Waves	Height (cm)	5～9	10～15	5～9	10～15	5～9
	Frequency (sec)	1	0.5	1	0.5	1
	wave ranks	1	2	1	2	1
Winds	Speed (m/s)	2.6	6.4	2.6	6.4	2.6
Amount of sea water (t)		4	4	4	4	4
Sea waterdepth (cm)		60	60	60	60	60
Sea water temp. (deg,C. )		25	25	10	10	17.5
Amount of oilcharged (L)		10	10	10	10	10
Slick thickness (mm)		1.4	1.4	1.4	1.4	1.4

Overview	Structure

3. Testing method

　The various apparatuses of the circulating water channel were set according to the conditions shown in Table 2 for each case in this test. In a waves stable state, the test oil of predetermined amount was poured calmly on surface of the circulating sea water. First day, the samples of test oil were taken after 0.5, 1, 2, 4, 6, 8 hour from the surface of sea water. After that the samples were taken at 24 hour intervals over a period of 4 days from the surface of sea water. And the properties of sample measured viscosity, water content, density and evaporation rate.
In addition, Photographs of the injected test oil were taken immediately after a test began, and at the 4,24,and 72 hour points.

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