29-12-2021, 06:05 PM
Hi
I am familiar with Bakelite from the world of vintage radio cabinets
Bakelite (Phenolic Resin) was used extensively for distributor caps, ignition coils and all sorts of other electrical items. The pure resin was bulked out with various fillers such as wood flour. I wasn't aware of asbestos as an ingredient, but its clearly a possibility. Bakelite has excellent insulating properties even at high temperatures. When moulded under high temperature and pressure, the outer shiny skin is near 100% resin and the filler fibres do not come all the way to the surface. A bit like the gel coat on fibreglass. A slightly dulled surface can be restored with telephone polishing paste, which is a mild abrasive mixed with wax. I would be wary of carrying out any kind of more agressive abrasive polishing, never mind grinding, sawing or drilling, due to the risk of exposing the previously safely "locked up" fibres. In any case, once the shiny skin is worn away, you will start to expose the filler fibres and you will never get the shine back. I suspect that the high voltage insulation properties if exposed to damp would also be compromised.
Modern replacements are unlikely to be bakelite, and some poorer quality plastics have proved inadequate for high voltage insulators as soon as the temperature is elevated. Maybe ignorance / lack of testing by the manufacturers ?
On a related theme, I once had to use Beryllium Oxide insulators for a job. Beryllium oxide dust is highly toxic, but the solid porcelain-like material is safe to handle as long as you don't grind bits off it. I was once summoned to goods inward to pick up a shipment, the chaps there had been put off by the skull and crossbones on the packaging and had placed it outside in the yard on top of a sand filled fire bucket as if it was an unexploded bomb !
I am familiar with Bakelite from the world of vintage radio cabinets
Bakelite (Phenolic Resin) was used extensively for distributor caps, ignition coils and all sorts of other electrical items. The pure resin was bulked out with various fillers such as wood flour. I wasn't aware of asbestos as an ingredient, but its clearly a possibility. Bakelite has excellent insulating properties even at high temperatures. When moulded under high temperature and pressure, the outer shiny skin is near 100% resin and the filler fibres do not come all the way to the surface. A bit like the gel coat on fibreglass. A slightly dulled surface can be restored with telephone polishing paste, which is a mild abrasive mixed with wax. I would be wary of carrying out any kind of more agressive abrasive polishing, never mind grinding, sawing or drilling, due to the risk of exposing the previously safely "locked up" fibres. In any case, once the shiny skin is worn away, you will start to expose the filler fibres and you will never get the shine back. I suspect that the high voltage insulation properties if exposed to damp would also be compromised.
Modern replacements are unlikely to be bakelite, and some poorer quality plastics have proved inadequate for high voltage insulators as soon as the temperature is elevated. Maybe ignorance / lack of testing by the manufacturers ?
On a related theme, I once had to use Beryllium Oxide insulators for a job. Beryllium oxide dust is highly toxic, but the solid porcelain-like material is safe to handle as long as you don't grind bits off it. I was once summoned to goods inward to pick up a shipment, the chaps there had been put off by the skull and crossbones on the packaging and had placed it outside in the yard on top of a sand filled fire bucket as if it was an unexploded bomb !