The use of a mixture of copper soap, 5 or 10 per cent, with 1 per cent mineral oil, dissolved in petrol or benzol, increases the life of silk plankton nets by about four or five hundred per cent, and roughly doubles that of a hemp net for a single treatment. The beneficial effects last far longer than does the green colour. Re-treatment at suitable intervals is recommended.

The use of 5 or 10 per cent of resin * with an equal percentage of the soap improves its adherence to the fabric, as does also the addition of tar or anti-fouling paint. For silk nets, to avoid clogging, only one-half per cent of resin should be used with 5 per cent of soap.

A liquid soap mixture, which may be used with paraffin oil, can be obtained by adding one pound of resin to one pound of melted copper soap, and then dissolving in one and a half pounds of carbon tetrachloride. When wanted, this is used to make up a paraffin oil soap solution of the desired concentration, but adherence is less than with petrol.