I admit that I have yet to read the Era 2 books or the short stories, so perhaps this is revealed in one of those books. Still, worth asking if it hasn't. I've done quite a bit of browsing over on the Coppermind wiki, about the magic systems of Scadrial. I don't mind spoilers, since they only make me want to experience the source material firsthand, so I pumped myself up for reading Era 2 by reading about Allomancy and Feruchemy. Compounding was right up my alley, as someone who likes to figure out how things would mix. After a while, a thought occurred to me.
What would happen if an Allomancer burned a charged Hemalurgic spike? Would it Compound, like Feruchemy? Would the Hemalurgic charge simply disappear? Would the Allomancer gain the Hemalurgic power permanently, as if... for lack of a better word, spot welding the Spiritual DNA of the Allomancer? Or would it be something else entirely.