Wow!
It's always incredible to tap the depth of expertise latent in the forum, and this is a case in point. Thank you everyone for your knowledge, and also the generosity of sharing it.
Joseph asked en passant what the application was – when I posed the question I hadn't any idea that there would be so many possibilities, so the idea that the application would affect the recipe was something I hadn't envisaged.
There are several applications where I have used superglue as a fix for something that is broken, and there is a bit missing or a minor gap to fill. Oft times this has been the rear light lens on something agricultural or something of that ilk.
This week I have been rebuilding a poorly chainsaw, and wanted to repair several cracks in a complicated plastic baffle directing the cooling air around the internals. I could buy a spare part, but the project has cost more than the saw is worth already, and the point of the project was to do the job with as many reclaimed or non original spares as I could. And before someone starts lecturing me on the safety consequences of grey market parts yes I know, I know. Suffice it to say I am choosy what risks I take.
I got the original idea of filler – and I'm guessing this is where I got the bicarb recollection – from a YouTube video of someone repairing guitar frets this way. I hadn't given enough thought to the issues of flexibility – so I need to work on that aspect.
So many thanks to all those who have taken part – if there are other ideas do please carry on – and my best rgds to all.
Simon