On 30/01/2011 19:36, 'Mike' wrote:
In general bonfire ash is beneficial, but what care must be taken when there
are 'unknowns'? Plastic vanishes, but metal survives in a twisted state
which can and has been removed. Mainly wood, paper, plant debris, but ......
?

Any comments and advice?

Most varnishes will burn away to nothing just don't stand in the smoke.
The only things I would worry about are not ever burning pvc plastics
and removing any sharps from the ash - mainly nails, screws and brackets.

BTW Coal ash is far too high heavy metal and boron content. Plants don't
mind the heavy metals so much but the boron does them no good at all.

Regards,
Martin Brown