[skyler]

I will be brewing 5 gal of bitter pretty soon with a pitch of 1318 - said to be a "true top cropping strain." Since I have never top cropped, I am wondering what to expect. Should I crop off everything on top, or just a third of it, or what? Also, will I be harvesting enough for a full 5 gal batch? A full 10 gal batch? Or just enough to build a starter with?

[majorvices]

I've never used that strain before but if it is a true top cropper you can pull a lot of yeast off the top. I have pulled nearly all the krausen off some belgian strains before and still got around 90% aa. Most of the yeast is still in the beer, so pulling 2/3rds should be fine. That said, it's gonna depend on the yeast how much you will actually be able to pull. Using the French Saison strain from WY regularly and I have a hard time top or bottom cropping that strain. But WLP500 tops and bottom crops nicely.

[euge]

You can make a starter but you can crop enough at the right time and you'll see signs of fermentation rapidly. You have to do it right at the height of krausen IIRC. I scooped out a couple cups of the krausen and it took off immediately in the fresh wort. Subsequent attempts revealed that cropping past the top results in a lag which increases the further you are from the peak of fermentation.

Makes great beer. If I brewed constantly this is the method I'd use.

[hopshead]

I top crop Wyeast 1318 all the time, it is my house strain.  I have kept this strain going from batch to batch for 10 different batches of beer before I opt for a new pitch.  How much can you top crop you ask?  A lot.  I would not crop all the krausen, you need that yeast to finish the beer currently in fermenter.  Generally speaking, if you crop approximately 1 cup of krausen and use that for your next batch you will PLENTY of healthy yeast and you should get a quick start on the next batch.  I like to boil water, cool it, then put the top cropped yeast in the water in a flask and refrigerate it until I brew the next time.  If top cropping becomes a practice you use a lot, I recommend two things, one use some servomyces or yeast nutrient when you brew and use pure oxygen for oxygenation of the batch.  Repitching yeast that is chronically under aerated (oxygenated) and depleting nutrients can cause poor fermentations.

Please post back and let me know what you think when you top  crop.  The 1318 LIVES on top of the beer, you should have no problems.