Hello people, from what you can see im new here. Given that this subforum is usually visited by members that might just be starting off , i would like to deposit some general observations on filtering.
While this thread might introduce some "home methods" of filtering , it does not aim to substitute logic and thought with simply "carrying out a recipe".Its worth (if any) is in the spirit of "Give a man a fish and he will be hungry again, show him how to fish and he will not be hungry any more".
Filtering is the proccess where one seperates a material from another by means of selective permeability. A rather crude ,but common, example is coffee making using a machine with filters : the solid coarse coffee particles are retained by the filter while the aqueous phase passes through carrying with it anything that could fit through the coffee filter filter pores. In one way or another everyone has used "filtering" methods at one point in his/her life, be it tea making or straining freshly cooked pasta. The difference between everyday filtering needs and filtering needs for extractions ,is that the filtering needed for extractions is much more demanding and serves a crucial function.While the worst thing that can happen if you dont filter your chamomile tea sufficiently will be just an aesthetically displeasing "sandy texture" , not filtering correctly in an extraction procedure will lead to a contaminated end material that may throw dosage calculations out of the window and also it could make working during the extraction more difficult.In some cases (like one described further ahead) it could lead to loss of product,and in an extraction case the product is not usually as abudant and easily found as coffee is!
Three starting hints that can make life in extraction land easier are:
1)When using any kind of filter, go from coarser to finer
2)Many procedures may require concentrating pooled liquids.It is at your best interest to filter well before concentrating.
3)Vacuum can be a very good friend,but never forget the lifelong friendship with gravity.It keeps you on the planet surface and can help you in filtration!
The first hint can be considered pretty much common knowledge,it deserves its own paragraph though. Using a very fine filter at the first stages of the extraction for seperation of plant material will lead to a cloged filter and a furstrated extractor.Try going from a coarser sieve to keep the coarse plant material in and strain it ,to a finer sieve and then to a coffee filter or the filtration medium/paper of your choice. Also ,if possible pick filters with a good wet strength, that is filter that will not tear easily even if strain is applied on them. A very good example of a somewhat fine filter (not by chemical standards but with household ones) can be a thin,densly woven T-shirt. It can take the strain of sqeezing to force liquid out without tearing apart. Always keep in mind to use your brain, let it not consume precious glucose to no avail : check if your filter is compatible with the materials you use.For example ,do not use a synthetic fiber T-shirt with a non-polar solvent without first checking if it will dissolve it, and preffer T-shirts that do not leak color.
The second hint can minimise loses. Loosing 5 ml of a solution per filtering, due to filter retention or accident, is almost of no importance if you solution to be filtered is a 1 liter dilute solution, such as the one coming from a first boil of a herb. Loosing 5 ml per filtering of your concentrated 100 ml solution ,is a more important loss. So consecutive,thorough filtering is best done at the first stages of the extraction and while laborious due to increased volume, the benefits outweight the patience spent!
The third hint can be a very useful one and sometimes can "side-step" classical filtration techniques or complement them. While vacuum allows for filtering that would be extremely hard if not impossible ,a vacuum setup is not something found in your cupboard.Here ,gravity can help. Given time fine particulate that can clog filters can accumulate at the bottom of the contair the solution is stored and then decanting can help. It goes without saying that given the nature of decanting (leaving some solution in the vessel) it is better carried out in unconcentrated solutions.
Keep in mind that nothing substitutes for improvisation and apart from "tried and true" techniques giving a go at reformulating some lab concepts suitable for home use.This forum has its fair share of ingenuity : If one searches,one can find that methods using vacuum cleaners for vacuum/sunction ,as well as using syringes with coffee filters in them have been used for filtrations of solutions. What follows are three propositions for those that judge its in their best interest to use vacuum or pressure for filtration.
1)Filtering with a squeezable plastic bottle and a fine cloth.
2)Filtering through a syringe by drawing liquid through a filter
3)Home versions of vacuum pumps.
The first method is a very easy one and lents itself to many modifications to suit your needs.All you need is a plastic sqeezable bottle (water bottles will do) with its lid, a fine but densly woven cloth and a knife.The basic concept behind it that the liquid is in the bottle and squeezing in will force it (pressure) to go through the cloth and get filtered.The cloth is held tighly at place by using the lid. Its construction is very easy:
a)Cut the upper part of the lid,in a way that the lid will still be able to screw on the bottle but water can go through it.
b)Put the cloth on the top of the unscrewed bottle and press it a bit in the whole: this will give more filtration surface making more difficult to clog.
c)Hold with one hand the cloth in place and firmly screw the lid on.
When you want to use it , unscrew the lid, remove the cloth and fill it with your solution.Replace the cloth ,screw tightly the lid and turn it upside down. Squeeze and filter!
This method can be efficient with bigger volumes of solution.
A modification of it could lead to a vacuum filtering device for bigger volumes akin to a buchner funel but requires some handywork.It is based more or less on the same principle of "securing" the filter in place and applying force on the liquid body..How to build a prototype is detailed below:
Materials
2 Same size wide mouth plastic jars with lids on
Filter of choice
Fine wire mesh (applicable in some cases)
Glue
Tools to cut through plastic
Small tubing
Construction
Take both of the lids ,cut them the way described on the "sqeeze bottle filtration device", but be sure to leave some of the top lid uncut,do not cut it away fully. In a vertical section the lids should look like an L not like an |,in a way that if a round filter is put on it, it can stand there..Now,glue them together in a "back to back" fashion.The idea is that if you now screw the plastic jars on the "conjoined lid" it should look like a hourglass.
The next step is to cut the bottom of one of the jars (which is going to be the top compartment holding the liquid) and puncture a whole at the jar destinged to be the liquid receptacle (the bottom jar) and insert there the tubing.
To use it you assemple it this way: Screw first the bottom jar on the conjoined lid.Place filter on the top lid, the fine wire mesh can be used if its a paper filter in order for the filter not to tear apart : in this case first put the fine wire mesh and then on top the filter paper. Screw tightly the top jar that has no bottom on it so filters are secured in place. Attach vacuum source in the tubing of the bottom jar and filter!
The second method is as easy as the first. The idea behind it is to use a syringe as a collection and suction vessel that will suck the solution through a filter. Here two kinds of syringes can be used ,both the ones for feeding with a "wide nose" at the front and no needle, and the ones with the needle. The filter of choice can be Rizla filter tips. To make it , the filter is attached where the syringe sucks from : in the case of a needle syringe ,the filter can be impaled on the needle.In the case of a feeding syringe the filter can be worked with the fingers on one end to make it able to fit in the hole. Preffer ultraslim rizla tips for that. In order to filter using it put the filter in the solution and pull the plunger back. It provides very fine filtration and its best from smaller volumes of liquids.
The third method requires quite some handywork but it can allow one to construct a vacuum pump ,either manual or automatic one.They can be made from fridge compressor units, from tire inflator air compressors,from bicycle pumps and last but not least a simple water aspirator creating vacuum can be made from a hose and tubing! Instead of detailing each procedure i will point you to the respective links for each of them. All of them are worth a view in my opinion.
Water aspirator from hose
Vacuum pump made from bicycle pump
Tire inflator compressor converted to vacuum pump
Fridge compressor converted to vacuum pump
I hope you find the above interesting and helpful!
While this thread might introduce some "home methods" of filtering , it does not aim to substitute logic and thought with simply "carrying out a recipe".Its worth (if any) is in the spirit of "Give a man a fish and he will be hungry again, show him how to fish and he will not be hungry any more".
Filtering is the proccess where one seperates a material from another by means of selective permeability. A rather crude ,but common, example is coffee making using a machine with filters : the solid coarse coffee particles are retained by the filter while the aqueous phase passes through carrying with it anything that could fit through the coffee filter filter pores. In one way or another everyone has used "filtering" methods at one point in his/her life, be it tea making or straining freshly cooked pasta. The difference between everyday filtering needs and filtering needs for extractions ,is that the filtering needed for extractions is much more demanding and serves a crucial function.While the worst thing that can happen if you dont filter your chamomile tea sufficiently will be just an aesthetically displeasing "sandy texture" , not filtering correctly in an extraction procedure will lead to a contaminated end material that may throw dosage calculations out of the window and also it could make working during the extraction more difficult.In some cases (like one described further ahead) it could lead to loss of product,and in an extraction case the product is not usually as abudant and easily found as coffee is!
Three starting hints that can make life in extraction land easier are:
1)When using any kind of filter, go from coarser to finer
2)Many procedures may require concentrating pooled liquids.It is at your best interest to filter well before concentrating.
3)Vacuum can be a very good friend,but never forget the lifelong friendship with gravity.It keeps you on the planet surface and can help you in filtration!
The first hint can be considered pretty much common knowledge,it deserves its own paragraph though. Using a very fine filter at the first stages of the extraction for seperation of plant material will lead to a cloged filter and a furstrated extractor.Try going from a coarser sieve to keep the coarse plant material in and strain it ,to a finer sieve and then to a coffee filter or the filtration medium/paper of your choice. Also ,if possible pick filters with a good wet strength, that is filter that will not tear easily even if strain is applied on them. A very good example of a somewhat fine filter (not by chemical standards but with household ones) can be a thin,densly woven T-shirt. It can take the strain of sqeezing to force liquid out without tearing apart. Always keep in mind to use your brain, let it not consume precious glucose to no avail : check if your filter is compatible with the materials you use.For example ,do not use a synthetic fiber T-shirt with a non-polar solvent without first checking if it will dissolve it, and preffer T-shirts that do not leak color.
The second hint can minimise loses. Loosing 5 ml of a solution per filtering, due to filter retention or accident, is almost of no importance if you solution to be filtered is a 1 liter dilute solution, such as the one coming from a first boil of a herb. Loosing 5 ml per filtering of your concentrated 100 ml solution ,is a more important loss. So consecutive,thorough filtering is best done at the first stages of the extraction and while laborious due to increased volume, the benefits outweight the patience spent!
The third hint can be a very useful one and sometimes can "side-step" classical filtration techniques or complement them. While vacuum allows for filtering that would be extremely hard if not impossible ,a vacuum setup is not something found in your cupboard.Here ,gravity can help. Given time fine particulate that can clog filters can accumulate at the bottom of the contair the solution is stored and then decanting can help. It goes without saying that given the nature of decanting (leaving some solution in the vessel) it is better carried out in unconcentrated solutions.
Keep in mind that nothing substitutes for improvisation and apart from "tried and true" techniques giving a go at reformulating some lab concepts suitable for home use.This forum has its fair share of ingenuity : If one searches,one can find that methods using vacuum cleaners for vacuum/sunction ,as well as using syringes with coffee filters in them have been used for filtrations of solutions. What follows are three propositions for those that judge its in their best interest to use vacuum or pressure for filtration.
1)Filtering with a squeezable plastic bottle and a fine cloth.
2)Filtering through a syringe by drawing liquid through a filter
3)Home versions of vacuum pumps.
The first method is a very easy one and lents itself to many modifications to suit your needs.All you need is a plastic sqeezable bottle (water bottles will do) with its lid, a fine but densly woven cloth and a knife.The basic concept behind it that the liquid is in the bottle and squeezing in will force it (pressure) to go through the cloth and get filtered.The cloth is held tighly at place by using the lid. Its construction is very easy:
a)Cut the upper part of the lid,in a way that the lid will still be able to screw on the bottle but water can go through it.
b)Put the cloth on the top of the unscrewed bottle and press it a bit in the whole: this will give more filtration surface making more difficult to clog.
c)Hold with one hand the cloth in place and firmly screw the lid on.
When you want to use it , unscrew the lid, remove the cloth and fill it with your solution.Replace the cloth ,screw tightly the lid and turn it upside down. Squeeze and filter!
This method can be efficient with bigger volumes of solution.
A modification of it could lead to a vacuum filtering device for bigger volumes akin to a buchner funel but requires some handywork.It is based more or less on the same principle of "securing" the filter in place and applying force on the liquid body..How to build a prototype is detailed below:
Materials
2 Same size wide mouth plastic jars with lids on
Filter of choice
Fine wire mesh (applicable in some cases)
Glue
Tools to cut through plastic
Small tubing
Construction
Take both of the lids ,cut them the way described on the "sqeeze bottle filtration device", but be sure to leave some of the top lid uncut,do not cut it away fully. In a vertical section the lids should look like an L not like an |,in a way that if a round filter is put on it, it can stand there..Now,glue them together in a "back to back" fashion.The idea is that if you now screw the plastic jars on the "conjoined lid" it should look like a hourglass.
The next step is to cut the bottom of one of the jars (which is going to be the top compartment holding the liquid) and puncture a whole at the jar destinged to be the liquid receptacle (the bottom jar) and insert there the tubing.
To use it you assemple it this way: Screw first the bottom jar on the conjoined lid.Place filter on the top lid, the fine wire mesh can be used if its a paper filter in order for the filter not to tear apart : in this case first put the fine wire mesh and then on top the filter paper. Screw tightly the top jar that has no bottom on it so filters are secured in place. Attach vacuum source in the tubing of the bottom jar and filter!
The second method is as easy as the first. The idea behind it is to use a syringe as a collection and suction vessel that will suck the solution through a filter. Here two kinds of syringes can be used ,both the ones for feeding with a "wide nose" at the front and no needle, and the ones with the needle. The filter of choice can be Rizla filter tips. To make it , the filter is attached where the syringe sucks from : in the case of a needle syringe ,the filter can be impaled on the needle.In the case of a feeding syringe the filter can be worked with the fingers on one end to make it able to fit in the hole. Preffer ultraslim rizla tips for that. In order to filter using it put the filter in the solution and pull the plunger back. It provides very fine filtration and its best from smaller volumes of liquids.
The third method requires quite some handywork but it can allow one to construct a vacuum pump ,either manual or automatic one.They can be made from fridge compressor units, from tire inflator air compressors,from bicycle pumps and last but not least a simple water aspirator creating vacuum can be made from a hose and tubing! Instead of detailing each procedure i will point you to the respective links for each of them. All of them are worth a view in my opinion.
Water aspirator from hose
Vacuum pump made from bicycle pump
Tire inflator compressor converted to vacuum pump
Fridge compressor converted to vacuum pump
I hope you find the above interesting and helpful!
