text: Q:
  
  Temperature when hydrating dry yeast
  
  Some Lalvin yeast I bought is not doing anything in my wort. When I told people on an online forum I'd hydrated it with 40°C water, they told me this was far too hot. But this is exactly what it said on the instructions so I'm wondering what to do.
  
  More details:
  
  This is Lalvin EC-1118 champagne yeast, bought just last week with a use-by of 2017
  I hydrated it as the instructions said and then added to 5L of must (one jar of honey)
  One teaspoon of nutrient was added
  A few little bits of 'scum' appeared on the liquid after two days but no airlock activity occurs, no krausen has formed
  The must is at a reasonably stable ~19°C, and has been for 3 days now
  
  A:
  
  All yeast are quite similar, really. It's surprising how different instructions manufacturers print for basically the same organism.
  From my experience, it is best to start with 30°C water. Then let it cool to about 20° before adding to wort. Unless I have an opportunity to actually speak with the one who wrote instructions, I simply ignore them if they tell me to go warmer. So far, so good.
  Even if for particular strain higher temperature is OK, don't just throw 40°C yeast to 19°C must. Let them cool. Imagine how you feel when you jump from hot sunny beach into a cold water. Not good, right? For yeast safe temperature difference is about 5°C, as far as I know. But I would try to get even closer if feasible.
  If you are worried about current batch, try rehydrating second package in lower temperature and adding it. If you are sure your conditions was sterile, you may want to wait up to three days. They still may kick in. Also, was your wort properly aerated? If not, this is the last moment to do it.
  
  