Gravity rising consistently during primary fermentation

Hi, apologies in advance as this one is a little long winded.

I am having a strange problem with a batch of stout. As is often the case in winter, bubbles did not pass through the airlock unless I manipulated the lid on the fermenter. Yeast deposits could be seen forming around the edge within a few days so I could tell fermentation was underway. No deposits on lid as it is a 30 pint kit.

I have only taken hydrometer readings closely for the last few years, prior to that I just used to checked the surface for bubbles by sight after around a week. I started using a hydrometer after the occasional volatile brews had added up. This is the first time that I have experienced an increase in hydrometer readings. I have checked through discussions (although so far not extensively due to time constraints) on fermentation but so far not come across anybody else with this problem.

Started: 29th January
Original Gravity: 1.042 at 21 Degrees centigrade
Subsequent Hydrometer Readings:
6th February (Day 8): 1.011
8th February (Day 10): 1.012
9th February (Day 11): 1.014
10th February (Day 12): 1.018

On the most recent check I noticed the slightest sour smell like when a batch is past being ready to bottle/keg. I doubt it is so far gone that it would go off within say 48 hours as there is a mixed surface of froth and clear liquid but after that I think I will be worrying a bit. 14 days is not unusual for one of my brews in winter so I am not in a rush that way.

My current intended plan of action will be to take a further reading on Day 14 for the purpose of record keeping. Then bottle up and keg with the slightest bit of priming sugar and leave the caps unscrewed for the first 24 hours which is what I do when I can't get the gravity below 1.006 before it goes off. I currently split my batches between a 2 GL pressure barrel and 2 litre plastic bottles so will also note any significant differences in either.

I am largely posting this information with the intention of it being useful to the site and members but any advice would still be appreciated. More information below that may be relevant.


Ingredients - all good bbe dates:

Kit: Young's Harvest Stout (one I have used several times with great success)

Sugars: 1.1 lb Extra Dark Spraymalt + 1.25 lb Enhancer (In the early days, I started with household granulated white sugar then switched to Brewing Sugar then combined Brewing sugar with Extra Dark spraymalt but this is my first all malt brew for stout)

Yeast: Full pack of the standard yeast which came with the kit (* at the moment I am assuming this was my possible mistake as I forgot the recommendation for all malt brewing is to use a superior yeast such as Munton's Gold)

Approx 6 pints of boiled water
Dechlorinated tap water to top up to approx 30 pints (just short of the 4GL mark)

Starting temperature: 21 Degrees centigrade
Original Gravity: 1.042

Storage: 5GL fermenting bin with lid tightly sealed and airlock fitted - ground level closed airing cupboard - sat on a flat supermarket standard insulation bag - no heating belt - basically the method I have used successfully for the best part of 40 years. I have a home made insulation jacket for extremes but as we've just had the warmest January on record ommitted using this. My home is compact, not drafty on the floor and retains heat well through cladding.


  • CelticTwilightCelticTwilight Member Posts: 28
    Gravity on day 14: 1.011

    Quite relieved tbh. Maybe it was the stirring which made the difference.
    That is a considerable drop over two days at this end. I am going to leave it for at least another day in the hope that the brew is well on its way. If it is dropping steadily at that rate it might be under 1.006 within 48 hours. As things stand it is roughly equivalent to business as usual.
  • HBO_StaffHBO_Staff Administrator Posts: 2,115
    Hi CelticTwilight, gravity readings increasing, especially by 7 points, is very unusual, sometimes the temperature can affect readings, but not usually by that much over several days. One thing that can affect hydrometer readings is if all the ingredients had not fully dissolved when the reading was taken so any sugars continue to dissolve, but you mixed with boiling water so they should all dissolve at the start.

    When brewing in an airing cupboard that is a constant temperature and around 21 degrees C that would usually be fine for a ferment too.

    It sounds as though a stir has helped get the yeast fermenting away as it should, and the readings are now dropping so should continue to do so, that's' good news and should make a good full bodied brew with the additions of the spraymalt and enhancer
  • CelticTwilightCelticTwilight Member Posts: 28
    Hi this was the start of a very difficult period for me hence the late response. I had a dodgy barrel with this batch when finally kegged/bottled up since resolved by HBO.

    From my notes this brew actually reached primary fermentation at 1.011 over 48 hours on day 16. Thanks also to a tip on here, I am now more familiarised with the Brewer's Friend site. For some time I had been following standardised advice (from kit instructions) of waiting for fermentation to be ready at 1.006 or below. Now I have the range charts to go by (stout being between 1.007-1.011) this is already helping a lot.

    After all the problems including having to bottle from a leaking barrel and warring with flies this turned out to be a truly excellent batch of stout on testing at week 5. The change in sugars has produced a drink more like Guinness whereas before I thought it was similar to Murphy's. So I now have some more experience at how to vary one of my favourite drinks and an idea how the master craftsmen do it. Sometimes the hardest journeys are the most rewarding. :)
  • HBO_StaffHBO_Staff Administrator Posts: 2,115
    Thanks for the update, this all sounding very promising and is great news the brews are turning out more to your liking, it's really great when a brew turns out so well especially after a few issues on the brewing journey, with any future batches you now can vary more to your liking and get brews how you want them, we're really pleased for you!
Sign In or Register to comment.

Howdy, Stranger!

It looks like you're new here. Sign in or register to get started.