There was a long thread on here a few years ago by a fellow named Mark (he went by the moniker “S. Cerevisae”. Mark knew more about yeast than the rest of us and he advocated the Shaken not Stirred approach, because the yeast are pitched at their highest vitality point, which was more important than merely number of cells. That has become accepted as a favorable approach, but the yeast are hardy critters and they will make beer with or without a stir plate or shaking vessel. I like the SNS method when making a starter, but a stir plate clearly works, too. However I prefer repitching slurry, frankly, when I have that option…
For me, the advantage of not using a stir plate is that it’s faster and easier.
Would pitching at “highest vitality point” mean high krausen? Would a stir-plate not also have that vitality point? Harder to see?
I’m still mostly cold-crashing and decanting.
The beauty of SNS is that you don’t have to crash and decant. Believe me, I did that for at least 15 years and hundreds of batches, and once I tried SNS I couldn’t believe how much time I’d wasted with crash and decant.
The minimalist description as seen above very much defines my approach to brewing. Being retired and on a fixed income with a relatively tight budget, and having returned to brewing only after a roughly 17 year brewing hiatus and only after retirement, modern brewing luxuries are not something high on my priority list. I’m still making it essentially the way I did from the mid-late 80’s to ~1998, but I make generally good beer overall, and occasionally I make really good beer. There is admittedly the occasional loser, but I’ve never had a batch that I’ve needed to toss out (yet). The most trouble I ever got myself into was when I attempted to brew and bottle a heavily dry hopped ~70 IBU IPA, and it rapidly oxidized and devolved into something several SRM shades darker than it was early on in the bottles, along with rapidly becoming less than desirable taste-wise. That one came quite close to being tossed. As long as I stick to older beer styles and don’t mess with dry hopping, things mostly turn out decent via my old school methods.
I actually made my own stir plate from a desktop computer fan with (as I recall, hard drive sourced) magnets glued to it, and it worked well, and (being a pack-rat) I may still have it around somewhere, but I soon decided that it didn’t improve anything related to my liquid yeast starters (which I try to avoid by mostly using dry yeasts), and (until today) I had forgotten all about it.
The originating hypothesis for the SNS technique was that spinning the culture would induce enough shear stress to damage the cells. AFAIK there’s no data available, at least not in the open literature (most large breweries use stirred propagators, so presumably there has been some work done).
I use a variety of methods for providing sufficient yeast for an optimal fermentation. Yeast propagation and revitalization methods I use are based on my yeast health, quantity on-hand, quantity needed, available time, desired effort, my current understanding of yeast knowledge and available tools in my toolbox with the ultimate goal of ensuring that my yeast handling process provides sufficient, healthy yeast for a fast start and complete fermentation with reasonably healthy yeast for cropping at the end of fermentation. I’m far from perfect but I give it my best shot each and every time 
Of the “large breweries” I’ve toured, most use orbital shakers (swirled propagators) which would indeed produce less shear forces than a spinning stir bar as well as having the effect of reducing yeast stress from carbon dioxide build-up. For those that don’t know the difference, it’s more akin to swirling a flask using your hand as opposed to using a “blender-like” method. Granted, a stir bar at very low speeds can have the result of (potentially acceptable) low shear forces while still keeping yeast well homogenized in the solution and helping to knock out carbon dioxide build-up (i.e. reducing yeast stress).
4 years (Old Dog…New Tricks | Experimental Brewing), but who’s counting besides me ;D
When Sean is talking large brewery, he means big. They probably have shake tables for intermediate steps, but there are propagators I’ve seen that are in the 20+ barrel size. Think Bell’s, Sierra Nevada.
This shows how they mix.
Time flies! Thanks for the correction.
While there may or may not be an advantage in that respect the fact that it’s faster, easier, and as effective is what sold me.
Shear-force seems like a good theory, but is there any evidence to support the impact of this? This really needs some experimentation, but my guess is that it wouldn’t make much difference at all.
Yeast seems like a hearty little organism, so I’m sure all of these methods make great beer. My issue is that I grow up yeast stocks from frozen 50ML vials, so growth is a real concern for me. I’ve never had any problems at all with my methods which are based on the growth charts here: Homebrew Dad's Online Yeast Starter Calculator
Cheers!
Personally, I keep forgetting to swirl, and eventually it foams up when I do. I don’t see why a stir plate is incompatible to the SNS method. Isn’t it really more about pitching yeast while active?
I start a few hours before I brew and start it on the stir plate. When it’s time to pitch, I pitch 1/2-3/4 of my starter and let the rest finish out. The extra hours into a jar or two until the next brew day.
Late to the party here: I sometimes use a stir plate, sometimes don’t. For lagers I always do (or use slurry). What I do use is half gallon/2L mason jars with these fermentation lids
I don’t tighten them down all the way until the starter is finished. They work great! And the jars way easier to clean and way cheaper than flasks.
No more traditional yeast starters for me! Now using SNS vitality starters.
Never used one, never needed one, never will use one.
For a starter, a one gallon jug containing harvested yeast, mixed with some fresh sterile wort, and agitated to wake up the dormant cells, is all we ever used.
Shaken, not stirred.