Mark Meckes
26th March 2005, 10:18 AM
Background
It is well known by homemakers, hobbyists and artisans that fresh cut flowers and herbs and plant materials can be dried in the microwave oven with good results.
Microwave drying is much faster, and the dried material looks fresher and keep their color better then other conventional methods. However if herbs contain a lot of moisture, the essential flavor can get cooked right out of the material, so timing is crucial and in many cases dehydrators and natural air drying works best at retaining flavors.
Procedure
The material is first placed on a paper towel, glass or special microwave container.
Flowers that require a support to prevent loss of shape are set on a layer of silica gel. Borax mixtures or expanded clay, (cat litter) can also be used, though they have more dust residue that can adhere to moisture laden flowers.
It is advisable to place a small cup of water in the oven before cooking to facilitate more even drying, and to prevent `hot spots' that can lead to combustion.
Materials are then heated at a medium to high setting for 30 seconds to one minute, after which they are allowed to cool for ten minutes. The paper towel may be replaced if wet, and the process repeated.
Flowers and herbs with high moisture content, after heating, should be left in the drying medium for several hours to overnight before reheating.
Experimentation with various temperature settings, cooking times, and intermediate cooling cooling/resting period is essential.
It is very important to keep a watchful eye on the procedure, as ignition of the materials can ensue, even for some time after the materials have been removed.
-------------------------------
So the question is, can bamboo pieces be successfully dried by microwave?
Following are links on the subject, from a preliminary research on the internet. Most of the information available is in reference to wood products.
From the National Mission on Bamboo Applications, India
Development of microwave based drying technology (http://www.bambootech.org/tslink.asp?subsubid=55&subid=1&sname=KNOWLEDGE&lid=110) for bamboo strips, slivers, intermediates and finished products.
- International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur, Hyderabad.
"Bamboo culms tend to have high moisture content, as do strips & slivers. Bamboo products & intermediates tend to pick up ambient moisture. This inhibits the manufacture of consistent & high quality products, especially in high and variable humidity areas.
Microwave heating provides uniform distribution of the thermal energy thereby remove water content more effectively cleanly and faster.
ARCI has developed expertise in microwave drying of ceramic-based honeycomb structures and has successfully demonstrated this technology.
Exploratory studies have been taken up by the ARCI have confirmed the efficacy of microwave drying. ARCI is now working towards design & installation of a continuous conveyer type microwave oven (of capacity 50 kg of batch/hr). This will be followed by field testing and validation."
--------------------------------
Microwave modified solid wood (MMW) products (http://www.crcwood.unimelb.edu.au/project1_4.html)
CRC Wood Innovations - Cooperative Research Centre, Melbourne Australia
"The application of very intensive microwaves for a few seconds to green wood results in an expansion of the wood cross-section (approximately 14%), with the formation of a multitude of micro-voids in the radial/longitudinal direction. This material has radically altered acoustic properties, strength properties, dimensional stability and permeability.
Permeability is increased by a factor in excess of 1200. The application of resin (6-8%) and compression back to the woods’ original dimensions leads to a doubling in wood strength, and an improvement in dimensional stability, durability and hardness."
---------------------------------
HOT TIMBER TECHNOLOGY (http://www.sciencealert.com.au/stories/CRCA/2004/hottech.htm) - Science Alert .com.au
Australian scientists have developed a microwave technology that has potential to revolutionise the world timber industry, slashing the time it takes to convert a green log to finished boards from months to days...
----------------------------------
Microwave Drying (http://www.ovwg.org/New-OVWG-Site/Techniques/Microwavedrying.htm) - Ohio Woodturners Guild
Discussion about drying green lathe work
--------------------------------
Microwave Drying Wood (http://homepages.ihug.co.nz/~rhaslip/Rex/workshop/microwave/microwav.htm) (lathe-turned green wood) - Notes by Rex of New Zealand
It is well known by homemakers, hobbyists and artisans that fresh cut flowers and herbs and plant materials can be dried in the microwave oven with good results.
Microwave drying is much faster, and the dried material looks fresher and keep their color better then other conventional methods. However if herbs contain a lot of moisture, the essential flavor can get cooked right out of the material, so timing is crucial and in many cases dehydrators and natural air drying works best at retaining flavors.
Procedure
The material is first placed on a paper towel, glass or special microwave container.
Flowers that require a support to prevent loss of shape are set on a layer of silica gel. Borax mixtures or expanded clay, (cat litter) can also be used, though they have more dust residue that can adhere to moisture laden flowers.
It is advisable to place a small cup of water in the oven before cooking to facilitate more even drying, and to prevent `hot spots' that can lead to combustion.
Materials are then heated at a medium to high setting for 30 seconds to one minute, after which they are allowed to cool for ten minutes. The paper towel may be replaced if wet, and the process repeated.
Flowers and herbs with high moisture content, after heating, should be left in the drying medium for several hours to overnight before reheating.
Experimentation with various temperature settings, cooking times, and intermediate cooling cooling/resting period is essential.
It is very important to keep a watchful eye on the procedure, as ignition of the materials can ensue, even for some time after the materials have been removed.
-------------------------------
So the question is, can bamboo pieces be successfully dried by microwave?
Following are links on the subject, from a preliminary research on the internet. Most of the information available is in reference to wood products.
From the National Mission on Bamboo Applications, India
Development of microwave based drying technology (http://www.bambootech.org/tslink.asp?subsubid=55&subid=1&sname=KNOWLEDGE&lid=110) for bamboo strips, slivers, intermediates and finished products.
- International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur, Hyderabad.
"Bamboo culms tend to have high moisture content, as do strips & slivers. Bamboo products & intermediates tend to pick up ambient moisture. This inhibits the manufacture of consistent & high quality products, especially in high and variable humidity areas.
Microwave heating provides uniform distribution of the thermal energy thereby remove water content more effectively cleanly and faster.
ARCI has developed expertise in microwave drying of ceramic-based honeycomb structures and has successfully demonstrated this technology.
Exploratory studies have been taken up by the ARCI have confirmed the efficacy of microwave drying. ARCI is now working towards design & installation of a continuous conveyer type microwave oven (of capacity 50 kg of batch/hr). This will be followed by field testing and validation."
--------------------------------
Microwave modified solid wood (MMW) products (http://www.crcwood.unimelb.edu.au/project1_4.html)
CRC Wood Innovations - Cooperative Research Centre, Melbourne Australia
"The application of very intensive microwaves for a few seconds to green wood results in an expansion of the wood cross-section (approximately 14%), with the formation of a multitude of micro-voids in the radial/longitudinal direction. This material has radically altered acoustic properties, strength properties, dimensional stability and permeability.
Permeability is increased by a factor in excess of 1200. The application of resin (6-8%) and compression back to the woods’ original dimensions leads to a doubling in wood strength, and an improvement in dimensional stability, durability and hardness."
---------------------------------
HOT TIMBER TECHNOLOGY (http://www.sciencealert.com.au/stories/CRCA/2004/hottech.htm) - Science Alert .com.au
Australian scientists have developed a microwave technology that has potential to revolutionise the world timber industry, slashing the time it takes to convert a green log to finished boards from months to days...
----------------------------------
Microwave Drying (http://www.ovwg.org/New-OVWG-Site/Techniques/Microwavedrying.htm) - Ohio Woodturners Guild
Discussion about drying green lathe work
--------------------------------
Microwave Drying Wood (http://homepages.ihug.co.nz/~rhaslip/Rex/workshop/microwave/microwav.htm) (lathe-turned green wood) - Notes by Rex of New Zealand