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Circuit Diagrams

Back in the July 1996 edition of the newsletter, we presented an article on the restoration of circuit diagrams affixed to the inside of telephone instruments.

This article suggested that diagrams should be photocopied in order to produce a copy that can be cleaned up to be photocopied again ready to fix inside the restored telephone. However, what if the diagram is glued to the inside of a bakelite case, maybe fixed to a curved surface where there is no chance of making a photocopy? How do you soften the glue to remove the diagram?

These questions have been raised by an American collector, a member of the ATCA. No-one appears to have satisfactory answers, so it is considered a good question to pose to you, the members, in the hope that someone out there has some solutions to the problem.

It has been suggested that the main problem is the type of glue used to fix the label. In Australia (and probably most other countries) a gelatine based glue (animal product) was used and this sets rock hard over the years. Using a solvent tends to dissolve the ink on the paper, water makes the paper break down, trying to "crack" the glue usually results in a torn diagram, methylated spirits may soften the glue, but not always.

If you have a tried and true method to remove circuit diagrams particularly in bakelite sets, it is sure that your fellow members would be eager to hear of it. Please send any ideas to the Editor for publication in a future newsletter.

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