BeerBorg

One of my first craft quality beers was a Belgian Strong that I made to Clone Brews' Rare Vos recipe. Three years later, the last few bottles are still excellent. One of it's shortcomings was lack of head. I did not carb it to style, but other beers with the same carbonation have plenty of head. I recently read that Palmer says that some head promoting proteins form only once. My beer at this point has carbonation, but no head. It differs in three ways from most of my batches:
1 Age. This is the oldest beer I still have.
2 ABV, at about 8.2% probably the strongest I've made
3 Sugar feedings. The recipe calls for sugar, and I added it by boiling, cooling, and adding when the original krausen started to fall. The batch used 3787, famously fierce, and had a couple of foam overs. Could I have reduced the later head by using up the compounds in my repeated krausens?
What do you think?

Interesting post you've got here. A little over two years ago, I made a Belgian Dark Strong. It too is still excellent (can't believe I still have some bottles left). I match your 1st and 2nd points. I also did two sugar feedings, but mine were not boiled and cooled first, they were just added directly as the gravity dropped, from what I remember, it was well after the krausens dropped. I did not have any foam overs. However, I also have the same lack of head that you have in yours. And they always did have a small head, so it's nothing that came about with old age. Hmmm? Now you have me wondering too.

Did your krausens "blow off" or did they remain in the fermenter and fall back in at some point?

I think that might be where you would "lose" some of those proteins.

One other thing to consider is that you likely added spices at the end. The flavor from the spices is carried by oils from those spices that end up in the beer. Those oils could suppress head retention. Many of my beers with lots of spices have very little head retention, except for ones that were made with lots of adjunct grains (oats/wheat) that added good amounts of proteins and/or beta-glucans to the grain bill or large amounts of crystal malts, neither of which you would have used in a Rare Vos clone.

Candi syrup on its own won't cause this, I have found that candi syrup (fully inverted - not just cane sugar) can actually increase head retention. My simple "Easy French Blond" recipe, although only 1.047ish and having 1/2# of candi syrup turns out with wicked head and lacing. And all it is, is Pils, 5L Candi Syrup, and Armais hops. But I do carb it to style too (as in a lot). And if I make it with just pils it seems to have less head retention. I don't know why, I just know that's how it works out.

FWIW, my oxygenated as hell APA like beer, when racking it formed a huge head in the bottling bucket because of how everything went wrong, and I thought that might screw up the head later in the bottle, but it seems to have made no difference at all.

EDIT: BTW, a long mash (especially at cooler temps) or a step mash can also reduce head retention because it allows more of the enzymatic action to affect head forming compounds.

Interesting.
My recipe did use spices, and did foam out of the bucket. I used .5# of candi sugar, and .5# of table sugar, because I contaminated the rest of the candi sugar while cooling.
The recipe was partial mash, 8# pilsner, 7oz C20, 4oz aromatic, 1oz chocolate malt, 3.3# Pilsen light lme, 3g coriander, 6g grains of paradise, .5oz orange peel.

It seems as though higher abv beers have lower retention. I have nothing to back that up. Just an observation. Just as higher hop conetent increases both head and retention.

My recipe did not use spices. The malt bill was 2 row, Vienna, aromatic, Special B, and a few ounces of smoked malt. My ABV came in at 8.8%. Looking back at my notes, I ended up bottling 58 bottles, which I think is a little more than 5 gallons. And if I figured my amount of corn sugar on 5 gallons, I may not have had enough. This may be why it's a little undercarbed, just not quite enough corn sugar to do the job.

John, did you bottle condition or keg?

Bottles, this was before I had kegs. But I individually prime the bottles with sugar cubes. I later found that one cube was often not quite enough, and bought small carb tablets to supplement, one cube plus one tablet. I did not do that for the recipe in question, but I did use carb drops for about half of the bottles. Those have more sugar. Just now I have looked back at the judges sheets from this recipe, scored in 2014. One says thin head, the other says large. Which indicates that this batch lost head during aging also.

I suppose suspended proteins / beta glucans, etc. might precipitate out (sink to the bottom as part of the bottle trub) given long time in the bottle, so that might change things with age.

@Beer Lord, so your recipe didn't have much crystal or other head forming compounds, do you remember if you mashed cool and long? Also, it might just be undercarbonation in your case, as even carbed to the high end of BJCP guidelines, is in my view undercarbed compared to what many real commercial Belgians of the various "styles" often are. I don't know where BJCP came up with their idea of what Belgian carb rates are. I think maybe just to keep 'Mericans from making bottle bombs. IE if your carb rates do not threaten to blow up 'Merican glass bottles, they they aren't carbed at all like commercial Belgians. (compare commercial Belgian bottles to the 'Merican ones). Since I use PETs I can carb the crap out of them without worry.