Very long boil times.

[BarryNL]

I've heard mention of people using very long boil times (3 hours+) when making barley wines, but none of the recipes I have here in my books suggest anything over 90 mins. Is there a purpose to a long boil, beyond maximising alpha acid conversion from the hops? What do you recommend as a boil time for a barley wine?

[Aleman]

Barry looking at the big Barley wine recipes in Old British Beers and How to make them , most of them are for a 2-3 hour boil.

I suspect that the real reason for this is to concentrate the wort a goodly amount, of course you also get a good degree of caramelisation of the wort.

The instructions given for a BW are to collect wort to 15 points under the gravity desired, then boil until you hit the published SG.

If you are making up the gravity with extract then you can probably get away with a 90 minute boil

[Vossy1]

I read that high gravity barley wines and beers have longer mash and boil times to aid stability for long term storage...can't remember where though, CBA perhaps

[mysterio]

Presumably it's to concentrate the wort down to boil volume, as you'll need to sparge for longer to get the same extraction from a 'normal' grist.

Personally i'd be tempted to bump up the base grain and sparge for less time and take a knock on the efficiency. If you are boiling for more than 90 minutes then you'll be getting some significant caramalisation. Subsequently you might want to think about adjusting your crystal malts down accordingly if you're doing such a long boil so you can get a fair level of attenuation.

This is just off the top of my head by the way, (having never done a barley wine I can't really give any practical advice).