A quiet airlock can be unsettling when you have just started a wine kit. Before buying extra yeast or assuming the batch has failed, take a specific-gravity reading with a hydrometer and compare it with your earlier reading and the instructions supplied with your kit.
This first article in our Craft Master Karl series draws on ABC Cork's Wine from Kits: What the Instructions Don't Always Tell You. The booklet explains a useful principle: different batches can look very different while fermenting. Your measurements help you decide what is happening.
Why a wine-kit airlock may be quiet
During fermentation, yeast converts sugar into alcohol and carbon dioxide. An airlock lets gas escape while helping protect the fermenting wine. It is useful equipment, but watching bubbles does not tell you how much sugar remains or whether your kit has reached the next step.
The booklet describes batches fermenting side by side with very different amounts of visible bubbling. One may look busy while another appears almost still. Treat that difference as a reason to check your records, rather than a reason to add an ingredient.
Check that the airlock is assembled, filled and fitted according to its manufacturer's directions. Keep the fermenter protected as your kit instructions specify. Never seal an actively fermenting container in a way that prevents fermentation gas from escaping.
Use a hydrometer to check fermentation
A hydrometer measures the liquid's specific gravity, often abbreviated to SG. Dissolved sugar raises the reading. As fermentation progresses, the reading generally falls. A series of readings is therefore more useful than one look at the airlock.
- Find your starting reading. Look in your wine log for the measurement taken when you mixed the batch. If you missed it, record the current reading and say that the starting value is unknown.
- Prepare your sampling equipment. Clean and sanitize the wine thief or other sampling tool, test cylinder and hydrometer using suitable products according to their labels.
- Take a clear reading. Let the hydrometer float freely in the sample, without touching the side or bottom. Read the SG scale at eye level, following the instrument's instructions for the liquid surface and temperature correction.
- Record and compare. Write down the date, SG, wine temperature and current kit step. Compare with your previous reading at the interval your kit instructions recommend.
For example, a change from 1.070 to 1.040 shows that the measured density has fallen. Those numbers illustrate a trend; they are not universal targets for transferring, stabilizing or bottling. Use the targets printed in your own kit instructions.
What your readings mean for the next step
If SG is falling: fermentation is progressing, even if the airlock is not putting on a show. Continue following the kit's temperature, timing and measurement instructions.
If SG appears unchanged: check your reading technique, temperature and the stage you have reached. A stable reading can mean different things early and late in the process. It does not, by itself, prove that the wine is ready to bottle.
If readings remain above the kit's target: gather your notes and ask for help before trying a restart. Adding extra sugar, nutrient, yeast or stabilizer without understanding the cause can complicate the batch.
Check temperature and keep a simple wine log
Measure the wine's temperature rather than relying only on how the room feels. Follow the range given for your specific kit and yeast. There is no single temperature or fixed number of days that fits every wine kit.
A useful log needs only five items: kit name, date, current step, temperature and SG. Add a note whenever you make a transfer or add a packet. These records help you follow the batch and give the support team useful evidence if something seems wrong.
Get help before making a costly guess
Do not move to bottling simply because bubbles have stopped. Complete the fermentation, stabilization and clearing checks required by your kit. If you need help, contact Crafted Series with your kit name, start date, readings, temperature and a photo of the instructions.
Starting your first batch? Read our beginner equipment and kit-size checklist, then keep the wine-kit instructions overview beside your kit's own directions.
Craft Master Karl | Crafted Series. Adapted from ABC Cork's Wine from Kits booklet, airlock and hydrometer sections. The instructions supplied with your specific kit and equipment take priority.