Der er noget brændhæmmende kemi i almindelig mineraluld.

Du kan jo prøve. Det er vel kun et problem hvis der er så meget brændhæmmende kemi i at dine joints går ud.
Er det til frø eller kloner? Kimplanter er noget mere følsomme end stiklinger, især for saltindhold i jorden. Jeg kunne derfor godt forestille mig at det til plantebrug er bedre renset, end det til isolation, så måske skal de bare ligge i blød et par dage og skylles godt. Rockwool er jo egentlig bare candyflos lavet af sand.

Rockwool is a man-made mineral fiber. The vast majority of Rockwool used in the world is used for insulation purposes much like fiberglass. However, the properties of Rockwool can be substantially changed by adjusting the mineral content. In the early 1960s it was found that following several modifications to the manufacturing process Rockwool would support and, under the right handling practices, promote plant growth. This specially produced horticultural Rockwool is what is primarily sold as a hydroponic substrate