I performed the first acidic boil of a 300g extraction and now there is a black film at the surface, what should I do with it ? Discard it ? Grind it and put it back ?

Thanks!

its normal when boiling to have this dark film.. It seems to be some kind of surface oxidation.. I always just mix it back in, noticed no issue at all..

Ive always just mixed it back in to the rest of the soup. Dont want to throw any goodness away

Actually I didn't have it when I used erlenmeyer flasks, probably because there wasn't much evaporation so no mhrb got stuck on the sides, I will use a lid for the 2 next acidic boils.

I've noticed after I've fridge decanted and filtered the initial acid soakes this film doesn't form when the tea is reducing. I'm guessing it's just small particles of the sticky sediment that stick together as they rise.

Bubbles are my friend to stop this stuff forming so I always check that there's enough heat so the surface is constantly being broken, but not so much that the whole thing boils over. Then I let it cool with a lid screwed on.

Very similiar to milk fat ? If so, I discard it but it could easily go either way. I mix my mixture quite often but it always forms after I let it cool down (outside), without a lid.