Thursday, March 6, 2014

Making Medicine Part 5 of 5: Pressing and Filtering a Tincture

This is the fifth and last post in a series in which I am using the process of wild harvesting and making a fresh herb tincture of blue vervain (Verbena hastata) as an example to explain in detail the process of making herbal tinctures. In Part 1 of this series I discussed the process of harvesting blue vervain; in Part 2, preparing the herb for macerating; in Part 3, preparing the maceration; and in Part 4 I discussed some of the common equipment that is available for pressing and filtering the maceration. Now we're going to look at the actual process of pressing and filtering our maceration to prepare the tincture.

As I indicated in Part 4, this final stage in preparing our tincture can be either a single or two part process. The standard method is to pour the maceration into our press. Much of the fluid (also called the macerate) will flow through, but not all of it. Then we apply as much pressure as our press will easily allow to squeeze as much of the fluid as we can out of the herb material (also called the marc). The better the press, the more fluid that we can press out of the herb. This is not only more efficient because we will end up with a greater volume of tincture, but our tincture will tend to be a bit stronger because the fluid that is deep withing the tissues of the herb will tend to contain the highest concentration of its constituents. Having macerated the herb for at least three months will ensure that the herb tissues have softened sufficiently to make it more easier for our menstruum to penetrate into the tissues of the herb, extract its chemical constituents, and be pressed out when we apply pressure.

With this method, the fluid that flows from the press will contain herb particles that are small enough to pass through. The fluid must then be filtered. The standard method is to allow the tincture to flow into a filter in a funnel placed over a large beaker or other kind of receiving container, and allow gravity to draw the tincture through the filter. Beakers are the best container to use because they have a large opening, are graduated, have a spout that will make it easier to pour the tincture into our bottles, and better ones will be made of borosilicate glass which is more durable. Although the graduations on a beaker do not allow us to accurately measure the volume of our tincture, they give us an approximate volume which allows us to determine the size and number of bottles we will need to store it.

For this process we do not want to use a paper filter as these are too fine. We need to use a fairly coarse filter because we want to include the fine sediment and other thick components like latex in our tincture. This means that it is best to use a cloth filter. It is critical that our filter does not contain lots of chemicals that are typically found on fabrics these days. The best fabrics are unbleached organic cotton, hemp or another natural fibre or combination of fibres. Muslin or some other coarse weave is best as long as it isn't fuzzy like flannel. Otherwise cloth fibres might end up in our tincture. Even when using a relatively non-toxic fabric to make our filters, it is best to wash them a few times and rinse them very well. We don't want soap in our tinctures! Cloth filters will last many years. They need to be scrubbed (by rubbing the fabric against itself) and rinsed well after use. Although it is best to use soap the first time we wash them and rinse them very well, water alone is best after their initial use. Soap isn't necessary because tinctures are sterile. However, it is important that the filters be allowed to dry completely before storing them.

When using a potato ricer, the macerate (fluid) and herb material are poured into the ricer, which is held over the filter.
The liquid will flow through into the filter. An cone-shaped unbleached cotton coffee filter works well for this.

The herb material (marc) is then squeezed to get as much liquid out as possible. Once the macerate
has completely flowed through the filter we wring it out to get any remaining fluid out of it.

In terms of funnels, the best funnels have a design that has a spiral cut into them. This reduces the surface contact between the filter and the funnel and allows the fluid to flow out more quickly. These funnels are usually make of glass or polycarbonate (plastic #7). We don't want to use polycarbonate plastic because it contains toxic chemicals that will leach into our tincture. That leaves the glass ones. However, they are very expensive, easily broken, and only marginally speed up the filtering of tinctures that have sediment or latex. Tinctures that don't have these components tend to filter relatively quickly anyway. As a result, I recommend solid plastic funnels. They are inexpensive and easy to obtain. That being said, we only want to use funnels that are made of polyethylene or polypropylene (plastics #1, #2, #4 and #5) as these are not known to contain any chemicals that will leach into our tincture (so far). If the funnel doesn't clearly indicate which type of plastic it is, don't use it.

With a screw press, the receiving cylinders must be removed from the frame of the press in order to
be able to easily empty the contents of our macerating jar into them. It is also important that
the beaker be at a lower level to allow the tincture to flow into it.

The biggest disadvantage of this method of filtering is that it is very slow. In fact, if the tincture contains a lot of sediment and/or latex it can be extremely slow, even with a very coarse filter. This is undesirable because the longer our tincture is exposed to light and especially air, the greater the amount of degradation of its active constituents that will occur. As a result, I always use the second method of filtering the macerate and that is to make cloth filters that fit inside our pressing device. This allows the maceration to be pressed under pressure. It only slightly slows down the pressing process and the end result is a filtered tincture that can be bottled immediately. The reduction in time will significantly reduce the oxidation of the components of our tincture and therefore improve its quality and how long it can be stored before use. With this method it is not necessary to use a funnel unless we are using a potato ricer as our press. With a well designed screw press or hydraulic press the tincture can be directed directly from our press into the beaker.

With a potato ricer the cotton coffee filter is placed inside the ricer. It's still a good idea to use a funnel because the tincture
doesn't flow out of the ricer as neatly as through a hose and the funnel provides a wider area for it to drain into.

Here's the same set-up with a screw press. In this case it's necessary to make filters that fit the inner cylinder
of the screw press as cotton coffee filters are too small and not the right shape.

We pour the fluid into filter and then empty any of the remaining herb material into it as well. There will always be some residue in the jar, so I will pour some of the filtered tincture back into the jar to rinse the last of the herb material out of it. then we fold up the top of the filter so that when we apply pressure to it none of the unfiltered fluid will flow out of the top. With herbs that have a latex or are very mucilaginous, the filter will sometimes clog up preventing the fluid from draining efficiently. If this happens, it is important that there is no excess liquid on top of the herb material in the filter when we press it or it will not be possible to prevent it from flowing unfiltered out of the top of the filter. In this case I lift the filter part way out of the cylinder and rock it back and forth to speed up the rate at which the macerate flows through. Once the level of liquid is below the top of the herb material, it is OK to fold up the filter over top of it and press it. With a potato ricer we simply press it as hard as we can; with a screw press we tighten the screw as tight as we can; with an hydraulic press we pump it as much as we can.

Tightening the screw.

Here's the actual process using my hydraulic press: pouring the macerate and herbs from the jar into the cylinder.

Pumping the press.

With this method, once we finish pressing the herbs the filtering process is also complete and our tincture is ready! We need to get our tincture into bottles as quickly as possible in order to minimize oxidation. It is necessary to use narrow mouthed bottles because they have a smaller air space and it's easier to pour out of them. Once more we want to use amber glass bottles. The bottles I use are called amber metric rounds. The best lids are plastic phenolic caps with a cone-shaped polyethylene liner as these lids seal the best and polyethylene is one of the two kinds of plastic that are suitable for this purpose (the other being polypropylene).

50 ml, 100 ml and 250 ml amber metric rounds. The equivalent in the US is 2, 4 and 8 oz. bottles, which are slightly larger.

It is better to store our tincture in several smaller bottles rather than one large bottle. This will significantly increase the shelf life of our tincture. Every time we open up the bottle and use some of it we are exposing it to more oxygen and increasing the size of the air space in the bottle. The tincture in the bottle we are using will degrade much more rapidly than tincture in a full, unopened bottle. Since I tend to press half or one litre jars, I store my pressed tincture in multiple 250 ml bottles. If you are making smaller quantities for personal use, it is better to store your tincture in 100 ml bottles. Just like with our maceration, these bottles should be stored in the dark. Presumably, the last one we fill won't be completely full. We'll start by using that one and not start another until it is completely finished. In this way each bottle remains undisturbed until we need it. For most herbs, the tincture stored in the dark in an undisturbed full bottle will maintain its potency for about 6 months to a year. However, once we start opening it and using it it's best to use it up within 4-6 months. They don't go bad. They just lose their potency. The timing I have indicated is what is ideal. It doesn't mean you should throw out a tincture if you don't use it all within that time frame. However, I like to do things as ideal as possible, so I usually don't press any more of a specific tincture than I can use within 4-6 months.

Pouring the finished tincture into storage bottles. For demonstration purposes I broke with the tradition of these posts. I did not press
blue vervain herb tincture (Verbena hastata) because I had plenty on hand. Instead I pressed a half litre of blueweed herb tincture
(Echium vulgare) which is from the Borage family and has similar properties as common comfrey herb (Symphytum officinale).

It's important that we label our bottles of tincture. The label should include the name of the herb, the part of the herb used, the potency of the tincture, and the date it was pressed. I always use the same bottles for the same tincture because the bottle picks up the aroma and energy of the herb. You will note from the photo that I use green masking tape for labels because it is relatively water resistant, can be written upon and looks pretty good. Each time I press a tincture I cross out the old date on the bottle labels and write the new one until the label is full. Then I start a new one. This is an efficient way to label them because the same label can be used many times and a quick scan of the label gives me an accurate indication of how much I am using that tincture. This information is important when it's time to harvest that herb in terms of estimating how much I will need for the following year.

So, that finally wraps up this discussion of making tinctures! I hope that you have found it useful. As I promised way back when I posted the first installment of this series, since blue vervain was the common thread, especially in the first three posts, I am providing detailed information on the properties and uses of this herb that is based on my research and experience on the Herbal Resources page of the Living Earth website in the form of a pdf document that you can download (link to pdf file). Enjoy!

Thank you blue vervain!


  1. This is wonderfully detailed... thank you for sharing!

  2. Hi Michael, I have just found and read your series on making tinctures. I am an absolute beginner, but wish to make tinctures out of the motherwort growing in my yard. Is the Labco press a good one?