The aim of this research is to improve the approaches used in the conservation of tears in doped-fabric skins of historic aircraft. Conservation at the Science Museum in London has been based upon traditional methods of repair, adhering a fabric patch with several coats of a chemical compound called ‘dope’ over torn areas. This dope is not only an adhesive, but also causes the patch to shrink and thus re-stretch the doped-fabric around the tear, but alternative conservation methods are now desired as it is believed shrinkage of the patches may initiate new failures.
Research into the history of doped-fabric as a material and the doped-fabric aircraft at the Science Museum was undertaken so that the collection could be evaluated in relation to the historic record. The application of FTIR-ATR, XRD and XRF to materials retained in the Science Museum archives and of samples taken from the aircraft on display demonstrated that the aircraft were re-skinned with traditional materials expected of a historic doped-fabric aircraft rather than newer synthetic ones.
The contraction caused by applying a dope to a fabric panel, and that of a doped-fabric patch to a torn area, was measured using Resistance Strain Gauges, and it was found that the contraction of the patch influenced the strain of material around it, and that the behaviour was anisotropic between the two main fabric directions, warp and weft. Tensile loading experiments also demonstrated that historic material failed at significantly lower loads than the modern materials used for patching. Based on these findings it is recommended that alternatives to doped-fabric patching, as has been practiced at the Science Museum, should be considered due to the potential impact of the patches on surrounding historic material.