different bottles, different foam

[Spartan300man]

I have an IPA, bordering on an imperial IPA, that has been in the bottle for about 3-4 weeks now. I've chilled and tried about 6 of them over the last week on separate days. Three of the bottles really foamed up when I poured them into a pint glass, I had to stop halfway through the pour and wait until it subsided, which took a while. I found myself gulping the foam like whipped cream to be able to pour the last third of the bottle. The other bottles poured fine without a real problem. They all went through the same cleaning and sanitizing routine, all from the same bottling bucket using a calculated amount of priming sugar (corn sugar). One difference could be the time in the fridge prior to opening, some of them were in there for several days while other for about 8 hours. The beer itself is fantastic, no off-flavors or issues that I can detect at this point.

What are some possible explanations for this?

 

[slym2none]

I think you answered your own question - the beer that had been the fridge for 3 days was the one that acted normal, and the 8-hour beers were the ones that foamed up.

 

[Spartan300man]

I don't think I've ever heard of that having an effect on foaming, so I guess I've learned something new today.
On a similar note, I had a batch of beer that I felt needed some 'aging', it was a bit green early on and started to mellow after each week went by. However, during a mental lapse while cleaning up my basement, I put it all in a fridge to get it out of the way. Does the aging effect still occur, perhaps at a slower rate, when the bottles are in a cold fridge?

 

[GuldTuborg]

How well did you stir in your priming sugar while bottling? That's the first thing that comes to mind. The cleanliness of your glasses would be next.

I suppose it's possible the time in the fridge had an effect, but 8 hours should be enough time to get the content down to temp, so I kind of doubt that was the relevant difference. If the difference was time spent in the fridge, I would suspect the amount of time spent out of the fridge was the more relevant factor. Have you tested other bottles that have similarly been sitting out warm for an extra week or two?

 

[Spartan300man]

I had another one with excessive foam that had been in the fridge for 3 days. When I opened the cap, it gave me a nice pffft. No gushing. But when pouring, the foam rises up and I can't pour more than about half the bottle in the pint glass.
When I bottled, I had the priming sugar water (boiled and cooled) in the bottom of the bucket first. Then I siphoned out of my fermenter with a tube that curled around the bottom of the bottling bucket, trying not to splash or aerate. I can't recall if I used my long plastic spoon and stirred that batch after the fermenter was empty. I did this past batch, but I can't recall if I did on this problem batch. The process of siphoning into the bucket creates a bit of a whirlpool and good mixing at first, but perhaps as the bucket fills up there is not a properly mixed solution without stirring? Not sure if that is it, but that will be a step that I won't miss in the future to eliminate the variable.
The foam from the pouring is coarse with larger bubbles with the thicker velvety foam on top. When the course bubble foam settles down, the residual foam is velvety (like a nitrous Guinness) and hangs on the sides of the glass thick and creamy. I had a couple ounces of carapils in that recipe, it was a standard IPA.