Re-used yeast not taking?

I just made up a 5 gal batch of Palm O' Porter, used the leftover yeast from the last batch of porter (same recipe). How soon is that supposed to start visibly fermenting. It has been 24 hrs, and nothing is happening. METHODS: After racking to priming bucket..bottled... etc, I left the primary sit (with airlock on, in storage room), came home from work, boiled up another porter, took the old primary, swirled around, poured into sanitized mason, let it settle out, then pitched into fresh wort. Anything wrong with what I did? Or do re-used yeast take longer to get going? Also, the yeast is a White Lab 1098, it took almost 36 hrs to start fermenting with the 1st porter batch, though I did not make a starter. Thanks!

When you say the trub settled out in the mason jar, the heavier trub settles to the bottom and the yeast is suspended in the upper area. Which part did you use?

A lot of times brewers just pour the new batch right on the remains of the former batch and that is why the brew takes off in record time.

Yeah I read about pouring the new batch on top of the old yeast cake. How To Brew did not recommend this (for whatever reason), so I just used the top brown liquid and left the heavy trub behind (from what was in the mason jar).

Well then my uneducated guess is there wasn't quite enough yeast in suspension for a quick start. If it doesn't take off in another day I might be inclined to use a dry yeast backup pack. Got any around to use?

Bob Loblaw said:

I just used the top brown liquid and left the heavy trub behind (from what was in the mason jar).

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Was it "liquid", like beer? Or a beige/brown slurry? I'm afraid what you might have done is throw the baby out with the bath water, so to speak. Hard to tell without more details, but it sounds like the yeast settled out, and you basically picthed leftover fermented wort (with a tinyt bit of suspended yeast) into your new batch.

If you pitched even a quarter of the leftover yeast (and aerated? You did aerate, right?), I think you'd see vigorous fermentation by now

1. Yep I have an ale packet lying around ready to use. Was going to use that in the morning if I see no fermentation.

2. The slurry was thick brown, only the big chunks settled out (only let it sit for 10 min before pitching).

Well it took off overnight, very strong fermentation now. Thanks for the advice though.

Bob Loblaw said:

Well it took off overnight, very strong fermentation now. Thanks for the advice though.

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Hey, good deal.