From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Comparative tests of standard insulating varnishes with Asiatic varnish.
| Identifier | ExFiles\Box 24\2\ Scan171 | |
| Date | 16th September 1921 | |
| EFC. AB. 23. X.1109 - COMPARATIVE TESTS OF STANDARD INSULATING VARNISHES WITH ASIATIC VARNISH. A bottle of Asiatic varnish received in January from Messrs. Royce Ltd. has now been used for tests in comparison with the present standard varnishes. Some pieces of tin-foil each 2" x 2½" were covered with two coats of the respective varnishes. Time to dry. Armacell (impregnating) about 24 hours. Paciderm (finishing) 15 to 20 minutes. Asiatic 10 minutes. Begins to dry so rapidly that it is difficult to apply smoothly. Thickness. All samples about .0005" per coat. The Asiatic can be peeled off the metal in one piece. Elasticity. The varnished foils were bent double each way. The paciderm cracked at once, but the Asiatic and armacell stood this repeatedly. Heating. Test pieces were placed on the carcase of a dynamo working at 90°C. Both paciderm and armacell softened at this temperature, but the asiatic was unaffected. Absorption. Samples were weighed, soaked in water for nearly 100 hours and re-weighed. The percentage of absorption, after deducting the weight of the tin-foils were, paciderm 11.2, armacell 63.7, Asiatic 0. The armacell became white after a few hours in the water, but on drying out, its normal transparent yellow was restored, but without its surface brilliance. Solubility. Immersion in engine oil and in petrol for 24 hours, produced no effect on any of the varnishes. Chemical stability. Both the paciderm and the armacell are destroyed by strong sulphuric acid in a short time. The Asiatic, however, is unaffected. It also withstands the action of nitric acid, which the others will not. Contd. | ||