Yes. I haven’t had great luck with it, but others have reported that pitching fresh active yeast has been effective at finishing out bigger beers that have stalled. I’ve found that patience is required.
I think you want a LOT of yeast for this, so a bigger starter wouldn’t hurt. Or slurry from another batch.
Here is a response from White Labs regarding autolysis and reducing the gravity.
Autolysis will happen as soon as there are dead yeast cells that begin to decay. It is recommended to remove old yeast as early and often as possible to avoid autolysis off flavors, but it can be a desirable flavor characteristic in some products.
For instance Champagne is almost entirely distinguished by autolysis flavors and this is intentional. They age it a minimum of 18 months to incorporate this characteristic. It may be desirable in certain aged beers as well.
As far as reducing the gravity, you are left with very few options. You can rouse the yeast and warm it up, or you can try pitching a new volume of highly active yeast. You want the yeast to be highly active so that it can endure the stresses of starting in a hostile environment. More yeast will only help if you have the available sugars for fermentation. It is likely that the addition of yeast will perform for a breif while and then cease action again. Hopefully this is enough to get you to the target final gravity. If not, you may have to repeat this process.
It is possible that the yeast have consumed all the available sugars and that the remaining sugars are too complex for the yeast to break down. This would be evident if adding more yeast did not effect the final gravity. In this case you would be limited to back blending the beer into a new wort and continuing fermentation as a new batch.
Stan also says that the last 10% of attenuation can take as long as the first 90%. At only 2.5 weeks you may be prematurely concerned.
I appreciate your thoughts. Not to be confused with the OP here, but as far as mine is concerned, it’s not going anywhere. I am certainly here to learn, though I’m used to the 10%/90% thing with wlp 530. I have a single point finishing hydrometer and enough fermentations under my belt to say that with some confidence. If there was any movement at all, I would leave it.
I don’t see a 1.016 FG as a high FG for a Belgian Quad. With some decent carbonation the beer will taste just fine. I have made Quads that finish in the low 1.020’s that were amazing and placed in several comps in the past. I find that sometimes when these styles dry out too much they lack a bit of character and sweetness that is noticeable in commercial versions. Just my 2 cents which doesn’t go for much nowadays… 
The reason why we want to avoid dumping yeast cells from a White Labs vial into 1.060 wort is because we are dealing with a unknown number of viable cells that may not be in the best of health. A large deferential between the amount of solute inside of the cell and the amount of solute outside of the cell will cause water to migrate through the cell membrane to outside of the cell, resulting in dehydration, which, in turn, can result in cytorrhysis (the complete collapse of the cell wall). It also helps that it is easier to dissolve oxygen in 1.030 wort than it is 1.060 wort.
Do you why pitch rate increases with respect to gravity? It’s because the osmotic pressures encountered in high gravity wort place a lot of stress on a yeast cell’s plasma membrane (i.e., the high solute differential thing mentioned above). If we couple the osmotic pressure problem with the fact that it is more difficult to dissolve oxygen in high gravity wort than it is low gravity wort, we quickly realize that we have to limit the number cell divisions that need to occur before the stationary phase is reached, as each division results in a mother cell sharing its ergosterol and unsaturated fatty acid (UFA) reserves with its daughter cell (replacement divisions will need to occur during the stationary phase; hence, we need reserves going into the stationary phase). Ergosterol and UFAs are critical cell plasma membrane health because they make it more pliable, which, in turn, is critical yeast cell metabolism.
An important thing to remember is that a yeast cell loses turgor pressure when it shrinks due hypertonic situations (high levels of external solutes). Turgor pressure is the pressure that pushes a yeast cell’s plasma membrane against its cell wall.
Another problem that we encounter in high gravity fermentation are high ethanol levels. Ethanol is hygroscopic, which results in water being drawn out of the cells through their plasma membranes, which, in turn, results in shrinkage and loss of turgor pressure. In effect, yeast cells quit fermenting at a point because they become too dehydrated to pass nutrients and waste products through their plasma membranes, eventually resulting in cell death.
With that said, we encounter two problems when growing yeast cells for use in high gravity fermentations. The first problem is basic biomass growth, that is, we need to increase the overall yeast cell count, so that our pitch rate is closer to maximum cell density. The second problem is that we need to grow cells that do not go into the yeast equivalent of cardiac arrest when pitched into high gravity wort. What we are doing by increasing the gravity with each step is progressively selecting cells that can endure higher and higher osmotic pressures. It’s basically survival of the fittest. The cells that do not have the right stuff do not replicate and are replaced by the offspring of cells that do have the right stuff. This selection process is basically what happens in the 6 → 8 → 10 progression that narvin mentioned. There is nothing magical about using a larger batch. It’s all fermentative growth.
That makes sense.
So, have you done a 2 step starter with a higher gravity wort for the second step? I might try that next time I want to go straight to a very high gravity batch(1.090+). Of course, there’s a certain point where it’s just as easy to make a lower gravity batch of beer as your “starter”.
Either Brad Smith knows something that the rest of the brewing world does not, or he needs to perform more thorough code reviews. My bet is that there is a bug in Brad’s software because here is a posting that he made on his site (http://www.beersmith.com/forum/index.php/topic,1928.msg7731.html?PHPSESSID=3ca218961138cfb86bbf62f439f229de#msg7731):
" The apparent attenuation numbers can be calculated by hand as follows:
* apparent attenuation = ( ( OG in points - FG in points ) / OG in points ) x 100*
"
To convert a specific gravity reading to points, we merely lop off the 1 and treat the number on the right-hand side of the decimal point as a whole number, which is equivalent to performing the following operation: (S.G. - 1.0) x 1000
Example:
1.087 in gravity points = (1.087 - 1.0) x 1000 = 87
1.023 in gravity points = (1.023 - 1.0) x 1000 = 23
(87 - 23) / 87 x 100 = 73.6%
S. cerevisiae - thank you for your feedback. I rely on Beersmith and rarely run calculations elsewhere. Moving forward, I will check via Excel.
Gravity was down to 1.021 last Saturday and I decided to begin chilling. This week will be 6 weeks since pitching. I believe that it may be down another point or two by tomorrow. Around 77% attenuation.
If you start chilling you likely won’t go any lower. If you’re happy with 1.021 that’s fine, but if you think it should be lower I would just wait.
I’ve left big beers for two months to reach terminal gravity. Sometimes you just have to be patient.
I haven’t left beer on the yeast cake for longer than 6 weeks. It’s about 45 degrees now, perhaps too cold for the yeast to continue nibbling.
Yes, I have stepped starters in gravity many times. I have also performed three step 1.020 → 1.040 → 1.060 starters when culturing yeast straight from a bottle of Chimay. I recently taught a very talented young brewer the process. He too was a doubting Thomas until he tried it on a RIS. He said that it went against everything that he had read on Internet forums.
If you think about it, there’s nothing magical about the process. The first level starter does all of the heavy lifting when it comes to resuscitating the culture and getting the cell count up. It takes at most two replication periods to reach maximum cell density when the slurry from the 1L starter is pitched into the 3L starter.
I have found that one does not even need a stir plate for this process. I used to use 5L and 10L media bottles before I took a hiatus from the hobby (they look like large versions of the orange-capped media bottle shown in one of my other posts). The beauty of using a media bottle is that it can be capped after pitching and shaken until the media is almost all foam. I still shake the 40ml starters that I inoculate from slant. I sold my 5L and 10L media bottles while on hiatus from the hobby. I have been thinking about ditching my stir plate for a shaker. Large media bottles are expensive enough that I can justify purchasing a used shaker and a couple of used shaker flasks (they look like Erlenmeyer flasks with baffles on the bottom). I am a little like James Bond in that I prefer my cultures shaken, not stirred. 
I also start cultures from a bottle at 1.20 or so, with other starters being 1.035-1.040. I generally don’t have attenuation problems, especially using WLP530, but 540 was one in the past I’ve noticed this issue with. It produces attenuation in the mid 70s, as advertised, but not the 88% that Rochefort gets. If I’m going to do steps, most of the time I’d rather reuse the yeast from a batch of beer and get two beers.
Re: Beersmith, he’s using degrees Plato for the apparent attenuation numbers. It seems like ProMash does this as well. Plato and specific gravity are similar, and measure similar things, but they aren’t linear and start to differ more at higher gravities. Degrees plato is extract percentage by weight, and specific gravity is a measure of density. I’m not really sure which one is more appropriate, though.
This is exactly what I was thinking. If I’m culturing from a bottle, I start low and step the gravity up with each successive step. Same methodology as S. is talking about, and it works quite well.
That surprises me. It’s not that foreign of a concept. Isn’t it also covered in Yeast?
Is there a particular advantage to one over the other?
Most amateur brewers are under the false belief that a stir plate spun at slow to medium speed increases yeast cell count, which could not be further from the truth. A culture that is shaken until the media is almost all foam immediately after pitching has more initial dissolved oxygen than a starter that is merely pitched and placed on a stir plate at a low to medium speed. A stirred culture has to be stirred at a fast enough speed to create a vortex down to the stir bar in order to provide adequate aeration. CO2 is denser than air, so there is very little in the way gas exchange in a flask after significant CO2 production has started.
I am also not convinced that spinning a stir bar at a high rate of speed does not beat the cells up because every starter that I have made on a stir plate has had the telltale smells and tastes associated with yeast stress. I have never had a shaken starter that I could not pitch without decanting the supernatant.
The major advantage that a stir plate offers over merely shaking a culture until it is almost all foam immediately after pitching is that it keeps flocculent yeast strains from prematurely flocculating. However, that advantage is almost insignificant when creating a starter because the goal is to produce yeast cells, not fully attenuate the wort; hence, we should be stepping or pitching the culture after we have reached maximum cell density.
Now, a stir plate combined with continuous aeration is an entirely different topic. However, that process requires us to sterilize (at least sanitize) another piece of gear.
Oh man, there was a long thread about this topic on the NB forum a couple of years ago that delved into partial pressures of gases, etc. It got a bit heated as I recall.
What about driving off CO2, is that worth anything?
What about hitting a stir plate starter with a bit of oxygen prior to pitching?
Actually, I remember that Kaiser did some experiments on this topic.
http://braukaiser.com/blog/blog/2013/03/19/access-to-air-and-its-effect-on-yeast-growth-in-starters/
That experiment pretty much correlates with my hypothesis.
This part of Kai’s hypothesis is on the money.
“yeast growth in wort is limited by available oxygen for sterol production. That means that access to more O2 allows more cells to be grown.”
However, the maximum number of viable cells that can be produced is limited by the maximum cell density per milliliter.
With that said, one thing that I am certain most readers will overlook in the experiment is the inoculation rate of 10.8 billion cells per liter. That inoculation rate is a fraction of the number of viable cells that are available from the average White Labs vial (it’s an order of magnitude less than that of a relatively new White Labs vial).
To grow from 10.8 billion cells per liter to 250 billion cells per liter (which is above the normal maximum cell density of 200 million cells per milliliter), requires the culture to undergo log2(250 / 10.8 ) replication events.
Note: log2 is the logarithm base-2 function, which can be performed on calculators that do not support it by taking the base-10 logarithm of 200 / 10 over the base-10 logarithm of 2 (i.e., log(250/10) / log(2)) or the natural (base-e) logarithm of 200 / 10 over the natural logarithm of 2 (i.e., ln(250/10) / ln(2)). This formula is the inverse of the basic exponential growth model after n replication events, which is cell_count_after_n_events = initial_cell_count x 2n.
number_cell_replication_events_kai_experiment = log(250/10.8 ) / log(2) = 4.53
To grow from 100 billion cells per liter to 250 billion cells per liter, the culture has to undergo log2(250 / 100) replication events.
number_cell_replication_events_fresh_white_labs_vial = log(250/100) / log(2) = 1.32
Stir plates appear to be yet another situation where the amateur brewing community has taken a technique that is rooted in science and generalized it to a point where the outcome from the technique no longer holds. In my humble opinion, little to nothing is gained by using a stir plate, stir bar, and a 2L to 5L Erlenmeyer flask at typical amateur brewer starter volumes. A stirred culture without continuous aeration offers no advantage over a well-shaken culture when propagating a White Labs vial, and a well-shaken culture has fewer possible sources of contamination.
A cheap and easy solution for shaken 1L starters is a 1-gallon glass jug with a sanitizable cap (be careful when pouring hot liquid in a glass jug because most jugs are made from untempered soda lime glass). For those who are not price sensitive, a 4L to 6L screw cap Erlenmeyer flask such as Corning model 4995-4L or 4995-6L can be a good investment if one takes care of one’s gear, especially if purchased used. A 4L to 6L screw cap Erlenmeyer affords one the advantage of being able to boil one’s culturing media in the flask. Larger starters will require a larger jug or flask (shoot for at least three times the starter volume).
Remember, the key to the well-shaken starter technique is using a vessel that is at least three times the size of the starter volume and shaking the starter until it is almost all foam after pitching. Periodically shaking the starter during the first six to twelve hours can be beneficial.
Doesn’t Kai’s experiment show that the stir plate helps to aerate the culture? I guess that is what I took away from the fact that the starter covered with an airlock grew less yeast than the starter covered with foil which grew less yeast than the uncovered starter.
If no aeration was being provided by the stir plate, wouldn’t you expect to see the same growth regardless of how tightly the flask was covered? Maybe a repeat experiment with control cultures not on stir plates would be needed to really answer that.
If nothing else, I suppose a stir plate can do the shaking for you while you are sleeping or at work.
I know of a stir plate aeration study being done now by a homebrewer and a couple microbiologists. It’s appearing that there is virtually no O2 added from the stirring motion, but the results aren’t complete yet.