I suspect you retained some metal powders from the mixtures. It contains both fine aluminium powder and coarse iron powder. It is advisable to extract
the iron powder first with a magnet before proceeding with the rest of the mixture.
Don't make the mistake of using very hot water to extract the barium nitrate, because exothermic oxidation of the aluminium powder will result in a
boiling mud and virtually no yield. It is better to use a large quantity of cold water and boil it down after filtering.
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