Some folks can find the maths in tincturing a little daunting but once you get used to it, it’s easy.
I’ve prepared this fully worked example of making a ratio tincture (aka weight to volume tincture) of fresh Brahmi (Bacopa monnieri) from our garden.
I harvested 200g of fresh Brahmi. We know that the best ratio for fresh herbs is 1 part herb : 2 parts alcohol, so we will need 400ml of alcohol. What percentage? Brahmi is quite moist, so a higher concentration of alcohol is preferred. The water in the Brahmi will be easily extracted and will dilute the final concentration, so we have a lot of room to play in order to make sure that the final tincture concentration is above 25% in order to preserve it well.
I have 85% alcohol, so I’ll use that. Will I have to dilute it and by how much? Let’s find out!
I chose a 50% alcohol concentration for the tincturing. At that concentration both the water and alcohol soluble constituents in the Brahmi will be extracted well. How much water will we need to add to the 85% alcohol to get a final amount of 400ml at 50% ABV
Let’s use the calculation from our 'A little about alcohol' page to work out how much alcohol and water to use to make a known quantity of finished alcohol at a desired concentration
(target %/original%) x final volume
Let’s do the bit in between the brackets first. Our target concentration is 50% ABV so we divide that by the original concentration of the alcohol which is 85%. 50/85 = 0.59
Now we multiply 0.59 x the final volume of alcohol that I want, which is 400ml. 0.59 x 400 = 236
That tells us that I need 236 ml of alcohol. Working out the water is simple. I know that I want a final volume of 400 ml and I know I need 236 ml of alcohol so I simply subtract the alcohol volume from the final volume. 400-236 = 164
To summarise, I need 236 ml of 85% ABV alcohol and 164 ml of water to give us 400 ml of 50% alcohol.
Now, the fresh, moist Brahmi will add a lot of water to the menstruum and dilute the final result alcohol concentration. Check out this post on working out the amount of water in a herb.
As a general guide, most herbs are approximately 80% water, so how much water will my fresh herb contribute to the tincture?
I have 200g so 200 x 0.8 = 160 ml of water is in the Brahmi. I need 164 ml of water to make my desired volume and concentration. The desired 164 minus the 160 from the Brahmi means that I only need to add 4 ml of water to the solvent.
The final amounts needed are 200g of fresh herb, 236ml of alcohol (85% ABV) and 4 ml of water to give me 400ml of solvent at 50% alcohol ABV
The fresh herb will not be submerged by the solvent, so putting both herb and alcohol in a blender is recommended.
Dried herbs
That’s a fully worked example of how to calculate how much alcohol, herb and water are needed to make a desired, final amount and concentration using a fresh herb. Using a dried herb, you of course use a ratio of 1 part herb : 5 parts solvent. Being dried, I can assume that the herb has no moisture in it so I can skip the part where I work out its contribution of water to the final concentration.
Some of you may have seen that I've been writing a series of posts about making herbal remedies at home. I want to share what I know of this topic so that, as the world gets crazier, folks will have other avenues of medical care, namely those of themselves and their community. If you look back over this blog, you can see heaps of info on the topic, plus loads and loads of posts on herbs and using Australian bushfoods from a white perspective. If you haven't been around on in the 
