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).
The properties and application of 'Impervo', a puncture-sealing and rubber-preserving product for tyre inner tubes.
| Identifier | ExFiles\Box 77\4\ scan0129 | |
| Date | 5th July 1922 guessed | |
| -2- USE OF PATCHES The principle of "Impervo" being pressure-resistance, it must have direct pressure to act effectively. In certain cases, we have found that leakages have occurred either at the joint in the tube or at the side of an old patch. Such air escapes may be described as "sideways leaks", and "Impervo" does not seal them because there is no direct pressure on the point of escape. When explaining "Impervo", demonstrators should be careful to point out this danger in using patched tubes. It must not be deduced from the above that "Impervo" cannot be used in a patched tube. Provided that the patch has been properly put on with the solution given plenty of time to dry before the patch is applied, there is no reason why patches should not be used. "Impervo" in no way interferes with the patching of tears or bursts on the road, which is a very important point to the cyclist; "Impervo" being absolutely non-sticky and soluble in water, it is an easy matter to obtain a clean surface for patching. VULCANISATION. Similarly, "Impervo" can in no way interfere with vulcanisation. If a tube is torn, all that need be done is to allow the "Impervo" time to gather at the bottom of the tyre before proceeding to clean the surface and vulcanise. Generally speaking, vulcanisation is preferable to patching, because with it there is no danger of a sideways leak. RESILIENCY. As only 5% of the air space in the tube is occupied, "Impervo" does not affect the resiliency of the tyre, nor has it any effect on the steering or running of a car. Any prospective user who is doubtful of this point can settle it definitely in his own mind by having only the near-fore and off-back wheels of his car treated. The running of a car fitted cross-wise proves this point beyond a doubt. PRESERVATION OF RUBBER Apart from its puncture-sealing qualities, "Impervo" is a rubber preservative, and a tube treated with it very rapidly becomes non-porous and therefore air-tight. This being so, it is evident that correct inflation is always maintained, and with correct inflation the motorist is rid of such troubles as cracked walls, rim bruises and stone bruises - so many potential causes of bursts. These rubber-preserving qualities of "Impervo" play their part in prolonging the life of punctured outer covers. When a nail is withdrawn, a certain amount of "Impervo" is forced through from the inner tube to the outer facing of the puncture and serves to protect the punctured spot against wet. | ||