What i know: Spunding is the natural carbonation. by brewers using a device called a spunding valve that allows for the setting of the head pressure in a fermentation vessel to predetermined level. What iI would like to understand /confirm: (i) If the brewer is using a secondary tank (rather than unitanks) can spunding be done in the secondary tank by applying counter pressure? (ii) Can 'full 'carbonation be achieved by spunding and does this depending on the plato level when transferring to the secondary? (iii) Why can't krasusening and priming with sugar, gyle or DME be considered spunding - after all it is natural CO2 too.... Do krausening and priming use head pressure to retain the carbonation produced? (iv) Does spunding have any effect on fermentation? Thanks
Are you (or do you know anybody who is) a member of the American Homebrewers Association? In the recent issue (March/April 2024) of Zymurgy magazine there was a detailed article about Spunding (including a fair number of equations). This article was an excerpt from the book Modern Lager Beer which will be released March 19. Cheers!
To spund, you need to have CO2 being produced by fermentation. I mean you could apply CO2 pressure from a CO2 cylinder. That's just force carbonation, and you wouldn't want a spunding valve involved in force carbonating. Most people don't force carbonate in a secondary fermenter, or in any fermenter, but there's no reason you couldn't, if the fermenter was capable of holding pressure. Some commercial breweries do it in their bright tanks. Yes, you can spund to any CO2 level you want, assuming you have enough fermentable sugars left and a fermenter that can handle the pressure. The spunding valve ensures that pressure beyond the equilibrium pressure for the chosen CO2 level is vented off, so that you don't overcarbonate. It's not spunding because there's no spunding valve to release any excess pressure. So you have to be more precise with the amount of sugar. There will be some CO2 (and thus pressure) in the headspace. But CO2 would be dissolved in the beer even if there were no headspace. The pressure slows the rate of fermentation.
Would it be considered cheating to add more priming sugar than necessary, then use a spunding valve to settle in at the desired CO2 volume? That way, the quantity of sugar doesn't have to be spot on.
