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).
Page 2 of a document discussing the removal of deposits by cleaning, compared to using mica plugs.
| Identifier | ExFiles\Box 130\2\ scan0234 | |
| Date | 30th October 1936 guessed | |
| -2- They do not claim entire absence of trouble, but claim that the deposit can be got rid of by cleaning, more throughly than with mica plugs. G.W.Hancock. | ||