Questions on how to reuse yeast

[richfei]

I have a 16 oz mason jar with about 8oz of yeast and 8 oz of water which I collected from a hefeweizen batch I made 3 months ago. It's been left in the fridge all this time. I want to reuse that when I make a hefeweizen again next week, but it'll be my first time doing this.

1) Do I just leave the yeast slurry out for a few hours so it comes to room temperature ?

2) How much of the 8 oz of yeast slurry do I use for a 5 gallon batch ?

3) Is there any conditioning that needs to be done i.e pour out the old water and transfer over to a new mason jar of water a few times to wash the yeast before adding to the wort, or is this step unnecessary ?

4) How long can this yeast slurry be left in the fridge before reuse ?

 

[Yooper]

Since it's 3 months old, use a yeast calculator (mrmalty.com has one for slurry), and make a starter. The 3 month old yeast will still be viable, but needs a starter to ensure that it gets going and that you are pitching active healthy yeast.