Mark Tatlow wrote:
John Bateson wrote: I have noted concerns about white glue causing bulges in inappropriate places.
Lead reacts with PVA to produce a form of cyanide. In addition to being rather expansive so it bursts open things like boilers, there is a rather worse reaction if you lick your fingers after handling.
There was a long piece in the letters page of MRJ; about 4 years ago. The general conclusion was don't mix em!
My chemistry is a bit rusty, but I can't see how PVA and Lead can produce cyanide. Cyanide is Carbon-Nitrogen, PVA consists of Carbon, Oxygen and Hydrogen. Lead is Lead. So, there doesn't appear to be any Nitrogen. There is Nitrogen in the atmosphere, but that is usually inert. Perhaps those who didn't give up chemistry over 25 years ago could add to this....
The damaging lead+PVA reaction is the slow conversion of lead to lead oxide. Lead oxide is a white powder. Lead oxide has a lower density than lead, so takes up a larger volume than the pure lead. Its the oxide (and its expansion compared to the pure metal) which causes the splitting when used in models. Lead and lead oxide are toxic, so wash hands thoroughly before eating or drinking.
For high density ballast, apart from the lead sheet mentioned above, the other I've seen suggested is to use tungsten based weights, which are now used in fishing so readily available.