69ron
Rising Star
Herb Filtration Techniques
After reading some people’s posts, I though it would be good to have a thread devoted purely to filtration techniques. So please feel free to add any pertinent information here on filtration tricks you may know of. I’ll start off by talking about a few tricks SWIM has learned over time.
Preventing Filter Papers from Clogging with Diatomaceous Earth!
OK, we’ve all experienced times when we’re filtering an extract and the filters keep clogging even when using a vacuum filtration system. Sometimes the filters get clogged and then break and all the particles fall into your filtrate messing up everything! That’s happened to me quite a few times.
Here’s the trick that pro’s use to prevent the filters from clogging. Add 1 cm of diatomaceous earth on top of the filter in the Buchner funnel, and then put another filter on top of the diatomaceous earth. The filter on top of the diatomaceous earth prevents the diatomaceous earth from moving around while you pour your extract over it. With this method, SWIM has never had a filter ever get clogged. With this method you can use really cheap filters. It slows down filtration a little, but since it won’t clog, you can let your herb extract filter overnight without ever changing the filter! It’s a great trick especially for those really hard to filter herb extracts.
Cold Filtering Powdered Herb Extracts
This method is very simple. After you boil your herb (or Soxhlet it, whatever) and it cools down, place it in a tall container in the refrigerator overnight. This causes the proteins and other particles to coagulate and settle out of suspension making them easier to filter out. Carefully and slowly pour of the liquid, making sure not to disturb any of the sediment in the container. Now filter the liquid while cold through normal filter papers to get out that last bit of plant solids. This technique is often used for cactus and similar herbs that are extremely difficult to filter.
Cotton Ball Filtering
Cotton balls, the type sold at pharmacies, are excellent for filtering. They are cheap and don’t clog nearly as fast as filter papers do. They are excellent for getting out all the large pieces, but don’t usually filter out the microscopic pieces. For those really tough to filter herbs, it’s sometimes good to filter through cotton balls first, and then filter through paper. Use a vacuum filtering system and use a normal funnel, not a Buchner funnel. Wet the cotton ball a little to make a good seal and to prevent it from popping up. Place the cotton ball in the funnel and press it into place with the vacuum turned on. Then pour the plant matter into the funnel. If it gets clogged, remove the cotton ball and put another one.
Glass Micro Fiber Filter Paper
These are pricey. They can be 5 times or more the price of normal filter papers. These filters are excellent though. They take much longer to clog and take far more force to break than normal paper filters. One filter can last as long as about 5 normal filter papers before clogging, so even though they cost more, they give much better performance making the cost worth it for some cases. If you’re filtering something that is really easy to filter, just use normal papers. But if you’re filtering something that keeps breaking or clogging normal papers than you need to use glass micro fiber filter papers. The other option is to use normal papers combined with diatomaceous earth.
Vacuum Filtration with a Buchner Funnel
Vacuum filtration is much faster than normal filtration (called gravity filtration). With a vacuum pump attached to the system, the liquid is sucked through the Buchner funnel. What normally would take hours to filter can be done in minutes.
As far as Buchner funnels go, the best type is the polypropylene two piece Buchner funnel. These funnels come apart and are very easy to clean and have a much larger capacity than a normal glazed porcelain Buchner funnel.
The normal glazed porcelain Buchner funnels have better chemical and temperature resistance though. They also cost more and are nearly impossible to clean because they don’t open up.
The other option is a fritted glass Buchner funnel. These have the best chemical resistance, are very pricey, but don’t require filter papers because they have a permanent glass filter built in. If they get clogged, you simply apply pressure instead of vacuum to unclog them. Because of this, they are reusable over and over. It’s similar to a permanent coffee filter, but made of glass. Because you don’t have to buy filter papers over and over, in the long run these can save you money. But they don’t filter out extremely small particles. The filter is usually either fine (about 5 µm), medium (about 10 µm), or coarse (about 50 µm). In comparison, fine filter papers are usually rated at 1 µm (1 micron).
Filtering Out Tannins?
Some plants contain a lot of tannins. Tannins are water soluble and need to be precipitated out before they can be filtered out. One common method is to add milk, egg whites, or gelatin. The proteins in these combine with the tannins and this causes them to be insoluble in water so that they can be filtered out. Before adding one of these, the herb extract should be acidic (about pH 4 is good). This method of precipitating tannins by adding protein is commonly used in wine.
Another method is to add calcium hydroxide (lime). When calcium hydroxide reacts with tannins, the result is calcium tannate. Calcium tannate is insoluble in water and so it can be filtered out. However, calcium hydroxide will make the extract alkaline, and may cause some alkaloids to become insoluble in water as well (harmine for example) and those would also get filtered out. Also it may decompose some alkaloids if too much is used (such as psilocin or bufotenine for example).
After reading some people’s posts, I though it would be good to have a thread devoted purely to filtration techniques. So please feel free to add any pertinent information here on filtration tricks you may know of. I’ll start off by talking about a few tricks SWIM has learned over time.
Preventing Filter Papers from Clogging with Diatomaceous Earth!
OK, we’ve all experienced times when we’re filtering an extract and the filters keep clogging even when using a vacuum filtration system. Sometimes the filters get clogged and then break and all the particles fall into your filtrate messing up everything! That’s happened to me quite a few times.
Here’s the trick that pro’s use to prevent the filters from clogging. Add 1 cm of diatomaceous earth on top of the filter in the Buchner funnel, and then put another filter on top of the diatomaceous earth. The filter on top of the diatomaceous earth prevents the diatomaceous earth from moving around while you pour your extract over it. With this method, SWIM has never had a filter ever get clogged. With this method you can use really cheap filters. It slows down filtration a little, but since it won’t clog, you can let your herb extract filter overnight without ever changing the filter! It’s a great trick especially for those really hard to filter herb extracts.
Cold Filtering Powdered Herb Extracts
This method is very simple. After you boil your herb (or Soxhlet it, whatever) and it cools down, place it in a tall container in the refrigerator overnight. This causes the proteins and other particles to coagulate and settle out of suspension making them easier to filter out. Carefully and slowly pour of the liquid, making sure not to disturb any of the sediment in the container. Now filter the liquid while cold through normal filter papers to get out that last bit of plant solids. This technique is often used for cactus and similar herbs that are extremely difficult to filter.
Cotton Ball Filtering
Cotton balls, the type sold at pharmacies, are excellent for filtering. They are cheap and don’t clog nearly as fast as filter papers do. They are excellent for getting out all the large pieces, but don’t usually filter out the microscopic pieces. For those really tough to filter herbs, it’s sometimes good to filter through cotton balls first, and then filter through paper. Use a vacuum filtering system and use a normal funnel, not a Buchner funnel. Wet the cotton ball a little to make a good seal and to prevent it from popping up. Place the cotton ball in the funnel and press it into place with the vacuum turned on. Then pour the plant matter into the funnel. If it gets clogged, remove the cotton ball and put another one.
Glass Micro Fiber Filter Paper
These are pricey. They can be 5 times or more the price of normal filter papers. These filters are excellent though. They take much longer to clog and take far more force to break than normal paper filters. One filter can last as long as about 5 normal filter papers before clogging, so even though they cost more, they give much better performance making the cost worth it for some cases. If you’re filtering something that is really easy to filter, just use normal papers. But if you’re filtering something that keeps breaking or clogging normal papers than you need to use glass micro fiber filter papers. The other option is to use normal papers combined with diatomaceous earth.
Vacuum Filtration with a Buchner Funnel
Vacuum filtration is much faster than normal filtration (called gravity filtration). With a vacuum pump attached to the system, the liquid is sucked through the Buchner funnel. What normally would take hours to filter can be done in minutes.
As far as Buchner funnels go, the best type is the polypropylene two piece Buchner funnel. These funnels come apart and are very easy to clean and have a much larger capacity than a normal glazed porcelain Buchner funnel.
The normal glazed porcelain Buchner funnels have better chemical and temperature resistance though. They also cost more and are nearly impossible to clean because they don’t open up.
The other option is a fritted glass Buchner funnel. These have the best chemical resistance, are very pricey, but don’t require filter papers because they have a permanent glass filter built in. If they get clogged, you simply apply pressure instead of vacuum to unclog them. Because of this, they are reusable over and over. It’s similar to a permanent coffee filter, but made of glass. Because you don’t have to buy filter papers over and over, in the long run these can save you money. But they don’t filter out extremely small particles. The filter is usually either fine (about 5 µm), medium (about 10 µm), or coarse (about 50 µm). In comparison, fine filter papers are usually rated at 1 µm (1 micron).
Filtering Out Tannins?
Some plants contain a lot of tannins. Tannins are water soluble and need to be precipitated out before they can be filtered out. One common method is to add milk, egg whites, or gelatin. The proteins in these combine with the tannins and this causes them to be insoluble in water so that they can be filtered out. Before adding one of these, the herb extract should be acidic (about pH 4 is good). This method of precipitating tannins by adding protein is commonly used in wine.
Another method is to add calcium hydroxide (lime). When calcium hydroxide reacts with tannins, the result is calcium tannate. Calcium tannate is insoluble in water and so it can be filtered out. However, calcium hydroxide will make the extract alkaline, and may cause some alkaloids to become insoluble in water as well (harmine for example) and those would also get filtered out. Also it may decompose some alkaloids if too much is used (such as psilocin or bufotenine for example).