What is Louching & How Do You Stop It

It’s time to cut back your alcohol with deionized water, but oh no! The alcohol has turned cloudy, and the cloudiness won’t go away no matter how much you mix it. What should you do? Never fear, I’ve had gin that louched a few times now, so it doesn’t really scare me anymore. In this post I’ll go over what louching is, how to prevent it, and how to fix louched alcohol.

What is Louching?

Spirit Distillation

We need to take a look at how alcoholic spirits are made. to understand what louching is. In this case, I will use gin as an example. A common method of making gin is the multi-shot method. In this method we fill a still with flavourless neutral grain spirit at 40-50% abv. Botanicals are added to the still and the heat is turned on. The rising heat will cause the essential oils in the botanicals to be carried upwards with the alcoholic vapours. When these vapours reach the still condenser, the oils, which are in vapour form, will change back into liquid form. The distillate collected is a gin concentrate. It has a very high alcohol content of around 78-80% abv, and is packed with essential oils from the botanicals.

Gins are usually around 40%abv when you buy them at the store. When you add water to bring the gin down to 40%abv it is normal for the gin to become cloudy at first since it isn’t fully mixed. There will be spots with more water and spots with more alcohol. Cloudiness is normal at this stage. The spirit should become transparent again after being thoroughly mixed and left to stand for 15-20 minutes.

Causes of Louching

If after 15-20 minutes the diluted gin remains cloudy, and will not clear with further mixing, then that gin has louched. Gin louching occurs when you start diluting your gin down with water. The more water you add, the greater the chance that the essential oils from the botanicals will come out of suspension from the liquid and cause the gin to louch.

Additionally, the type of botanicals you use will impact the likelihood of your gin louching. If you use botanicals that have a higher oil content, then there is a greater chance that your gin will louche when you start diluting it down.

How to Prevent Gin Louching

Now that we know what gin louching is, what are some things we can do to prevent it from happening?

SOLUTION 1: Take a Bigger Heads Cut

You can take a bigger heads cut during the distillation. In other words, as soon as spirit collection begins you will start collecting the distillate in a smaller vessel. This first portion of liquid that comes off the still is the “heads”, and will be separated out and often discarded. In my case, I usually collect 18L of gin concentrate, and make a very small heads cut of 100mL. I could increase the heads portion to 200mL in order to remove more oils and prevent louching.

You might need to take more than this volume of heads depending on your gin recipe, so experimentation will need to be done to figure out where to make your heads cut for each gin recipe.

You might be wondering why there are so many oils present at the start of the distillation. Since oils are heavier it would make sense if they were present in greater concentrations near the end of the distillation rather than the beginning. I was wondering the same thing myself, so I asked Odin, the founder of istill, why this was the case. He said that because the still takes time to heat up. The first fraction will be distilled many times as the vapour hits a cold section of the still, turns back into a liquid and gives off its energy to heat up the still. This process leads to an over concentration of early oils that needs to be discarded.

SOLUTION 2: An Earlier Tails Cut

Another method of removing the oils during distillation is to make an earlier “tails” cut. In this way, you can avoid collecting many of the heavier oils near the end of the distillation. However, doing this will leave you with less gin concentrate overall, and ultimately less gin.

SOLUTION 3: Dilute with Less Water

If you have already finished the distillation and are adding in deionized water to dilute the concentrate, you can still prevent louching by diluting your gin with less water. Instead of diluting the gin to 40% abv, you could dilute it to 45-46%abv. At this alcohol percentage, the oils are unlikely to come out of solution and make the gin louche.

SOLUTION 4: Adding More NGS

If you have made a mistake and the gin has already louched, you can usually reverse the problem by adding neutral grain spirit to raise the overall alcohol percentage of the gin, and give it more solvency power. Let’s remind ourselves what a solvent is.

Solvency definition:  A substance in which another substance is dissolved, forming a solution. b. A substance, usually a liquid, capable of dissolving another substance. The oils will go back into the solution, and the gin will turn clear again.

If you are a home distiller, adding more neutral grain spirit (NGS) to raise the alcohol content of the overall spirit is a good solution. However, if you are working as a distiller and your customer has asked that you make 200L of gin at 40% abv, then you cannot simply add in more NGS, as to do so would put the product out of your customer’s specifications. What to do…what to do?

SOLUTION 5: Chill Filter

You could chill filter your gin. In order to chill filter the gin you would first have to cool the gin to around 0°C. Afterwards, the gin would be passed through an adsorption filter to remove the haze. The oils that cause the haze will be removed, but these oils are also what give your gin flavour and a richer texture. This means that when you chill filter your gin you are also making your gin less flavoursome. This isn’t ideal, and also requires more time and money to do.

Is Louching Really That Bad?

What is wrong with a louched gin? Nothing really. Louching is a sign that the gin has tremendous amounts of flavour in it, so congratulations if you have a gin that’s louched! A cloudy gin will often taste much better than a clear one, since it has more botanical oils in it.

If you go out and buy a bottle of gin today, you’d be hard pressed to find a cloudy one, since they are considered not as aesthetically pleasing to look at as a clear bottle of gin. This is certainly a shame, but I hope this post has helped de-mystify why gins turn permanently cloudy sometimes.

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