How to Use A Wine Airlock At The Beginning Of Fermentation
During the first few days of a fermentation, the wine yeast is in a multiplying stage. It is devoting a significant portion of its energy to reproducing itself. On average, the wine yeast will multiply itself to around 100 to 200 times the amount of wine yeast you originally put in the must.
This is known as the "Primary Fermentation." Later, once the yeast has fully created the number of cells needed, it will then devote most all of its energy to creating alcohol. This is known as the "Secondary Fermentation."
The cell reproduction stage is necessary to successfully sustain a healthy, vigorous fermentation. If the wine yeast does not multiply successfully then the remainder of the fermentation will become sluggish and drawn out, and in many cases the wine yeast will give out completely before it has completed the task placed before it.
For the wine yeast to be able to multiply itself to it fullest ability, it needs air during the primary fermentation. Using a Wine Airlock during this time seals the fermentation from much need air, in effect, suffocating the wine yeast and putting a damper on its reproductive activity.
Instead of using an Wine Airlock during the Primary Fermentation, simply cover the container with a thin towel, cheese cloth or something similar. You can secure it by tying it down with a string to make sure it doesn't get knocked or blown off. By doing this you will allow the wine yeast to get all the air it needs without allowing bugs and other little nasties from getting in the mix.
After about 4 to 6 days of fermentation the wine yeast will go into its slower, secondary fermentation. This is the time when the wine airlock should be used. The air is no longer needed, and in fact, is a detriment to the must at that point.