Fw: life of bamboo treated by immersion

[Shyam K Paudel]

Enquiry from a bamboo lover. Pls repond

 

 

 

----- Original Message -----

From: peeyush sekhsaria

To: peeyush sekhsaria

Cc: shyam paudel

Sent: Wednesday, February 18, 2009 7:52 PM

Subject: life of bamboo treated by immersion

I am trying my luck for the third time with this query on bamboo treatment by immersion. I have a couple of questions which hopefully may find an answer on this forum I am presently helping design a brochure on bamboo treatment as practiced by a group in Gujarat India. They treat their bamboo (bought dry from the local market) by immersion. They even out the bamboo at the nodes, drill holes on either side of each node and immerse it in a water based solution of  boric acid + copper sulphate and sodium bicarbonate. This method seems to have served them well and bamboo treated in 2001 are still doing well. They have been used for roofing - trusses and as wattle in wattle and daub walls that have been finished in lime render. My questions 1. How is the bamboo likely to behave with time with respect to the effects of this treatment method for exposed (roof elements) and covered (wattle and daub) uses 2. How does one best dispose off the solution after the treatment is over Thanking you Peeyush

[senorpescado]

wish to try this for struts of bamboo for domes

[Scott]

Due to varying circumstances, I don't a think timespan can be
accurately given.

From what I've read immersion works well with split bamboo, but not so
well with whole culms.

[an...@ar.itb.ac.id]

I have an experience of using bamboo as roof-singles at the East Bali
Poverty Project (EBPP). The preserved bamboo perform much better than
non-preserved bamboo (see the attachment).
As I am now studying in RWTH Aachen, I have an access to Lab of Material
Science, and they have equipment to test the durability of material. The
chamber can be simulated as a micro climate of everywhere in the world.
The effect of temperature, humidity, sun exposure, etc, can be calculate.
I'd love to make a research cooperation in this area.

regards
andry

[guruprasad rane]

Dear Peeyush

1. How is the bamboo likely to behave with time with respect to the effects of this treatment method for exposed (roof elements) and covered (wattle and daub) uses?

Bamboo is made up of mainly fibers and starch. Starch invites insects. Fibers provide strength. Immersion treatments (Boric Acid & Borax) basically dissolve the starch thus reducing the chances of insect attack. Copper sulphate seems to make bamboo little fire resistant (I dont know How it does). Roof elements might crack after prolong exposure to Sun and Rain. Most of the cracks are small and on the upper layer of Bamboo thus the roof may not leak due to craks. Performance of bamboo inside wattle & Daub Walls mainly depends on the performance of plastering. As long as walls are dry and free of insects it will last long.

2. How does one best dispose off the solution after the treatment is over?

Let the tank dry out. Let the complete water evaporate then collect the chemical powder and dispose it or keep it for further use.

Regards
Guruprasad Rane
Sr. Architect
Habitat Technology Group
www.habitattechnologygroup.org

2009/2/19 Shyam K Paudel <spa...@inbar.int>

[Dave Hodgkin]

Peeyush,

Seems there is a range of answers and yet no clarity

I have faced the same confusion and hence undertaken a bit of research around these things

So whilst i make no claim to be an expert perhaps I can help clarify things a little

Firstly by saying that with the little information provided there is no possible way to tell you how long the bamboo will last

Durability of bamboo is affected by a vast range of factors, including but not limited too:

-Species type

     Different species have different levels of a range of important components such as silicone and starch in their structure

     This makes them effectively 'yummier' or less 'yummy' to different pests and forms of rot

-Harvesting time

     Levels of sugar and starch within a culm vary greatly throughout bamboo's life cycle. 

     The time of year, time of day and how many years old a culm was when harvested will all result

      in great variations in thee edibility of the end product

-Handling and storage

      As the outer husk of bamboo is highly silicaceous and therefore relatively impenetrable to pests, 

      most (certainly not all) pest infiltration occurs at nodes, cut ends and cracks and gaps in the outer shell

      Hence the amount of damage the bamboo has received through improper handling, storage of drying

      Will greatly effect it's durability

-Leaching

      Leaching of starches and sugars immedietly after harvest, prior to immersion treatment will again

      greatly reduce edibility and hence increase life expectancy of bamboo

-Treatment

      Solution strength, length of immersion, temperature, pressure, altitude can all effect the quality of treatment systems

- Exposure in usage

      Levels of exposure to sun bleaching and rain leaching or ground contact moisture will greatly effect the durability of bamboo

      One of the great things about borasic treatment is how fine the borasic particles are and therefore how readily they penetrate 

      throughout the bamboo culm. Borasic particles are so small they will wander through the cellular wall

      Unfortunately this means they are just as readily leached out by rain or contact with ground water

-Maintenance

      Spot treating pest infestations, replacing sections that are highly infested, oil or paint coatings, all can and do reduce pest damage 

      and therefore increase life expectancy of bamboo in situ

Add all this together and you can reach conclusions like:

- In worst cases, untreated bamboo can last as little as 6 months

- In best cases untreated bamboo can last decades 

(there is evidence of buildings that have lasted centuries, though most that i have heard of have been smoke or herb treated in someway

  and have maintenance regimes that probably replaced faulty components (such as temples))

Well treated bamboo, through immersion or pressure treatment, when well installed should readily last at least 20-30 years

Regarding disposal and reuse of the solution

I really am not an expert, but I can say that the Borax and Borasic solution is fairly inert and of little harm to the environment

I gather the the copper sulphates and sodium bicarbonate are more there to assist in the viscosity of the treatment and therfore its penetration with the copper adding an antirot/mould factor. Please someone correct me if i am wrong?

There is a simple method for separating out the sugars and starches from the solution and then reusing it. I am no expert, so I would suggest you contact EBF in bali or the like... but thanks for the reminder that i need to document that better !!!

One earlier response stated 

"Immersion treatments (Boric Acid & Borax) basically dissolve the starch thus reducing the chances of insect attack. Copper sulphate seems to make bamboo little fire resistant"

As far as I know this advice is incorrect, please anyone correct me if i am wrong, but:

but Borax (salt) and and Borasic Acid are just two forms of Borates which act as 

a) A fire retardant used in many household insulation products such as wool, cotton and paper insulation. 

B) An insecticide, as it is poisonous to the metabolic system of insects when ingested and the course angular dried particles are damaging to the exoskeleton of insects.

I gather the reason for using a mix of the acid and the salt are to improve the ease in which the borates are dissolved into water and dissipated throughout the bamboo, as well as gaining a protective effect from both the saltiness and the acidity of the solution reducing its palatability to pests

Borasic acid is as i understand it generally made by dissolving Borates in Sulphuric Acid whilst Borax is borates in a salt form

Its seems worth noting that one effect of the borax salts is to actually increase the wicking potential of bamboo, increasing the importance of protection from ground contact

Copper Sulphate is i gather primarily added for it's fungicidal properties, though i gather it too has an insecticidal effect as well. As faar as i know Copper Sulphate is generally formed by dissolving copper ( i gather commonly copper oxide for ease) in sulphuric acid. 

I have mostly heard of it's use in timber more than bamboo as most research seems to suggest the Borax/Borasic solution is adequate, though perhaps in highly moist tropical environments or with some species the fungacidal effect is of real advantage

The Sodium Bicarbonate... I guess this is being added either to increase the saltiness and therefor inedibility of the bamboo, perhaps also as an alkaline to balance out all the acid that is being added. It may also be there for it's surfactant effect, lowering the viscosity of the solution particularly after starches become dissolved

mmm...

Peeyush

did that help?

I've started  to document this in a set of guidelines 

www.humanitarianbamboo.org/guidelines

any input or thoughts about this document truly welcomed 

(though i'm off in the Tanami Desert for a while so may be slow to respond)

Can anyone correct me where i may have made a mistake 

I always appreciate the input

I'd like to use some of the questions and composite answers to produce an FAQ at humanitarianbamboo.org 

Yours

dave

Dave Hodgkin
Environmental Housing &
Emergency Shelter Consultant
BENCHMARK CONSULTING

Indonesia
Mobile +62813 92099666
Office +62274 6993735

Australia
Mobile +614 08816345
Office +612 61003312

2009/2/27 guruprasad rane <ranegur...@gmail.com>

[Scott]

David,

Thank you very much for the detailed answer. I have read everything I
can on preserving bamboo, however your post provided me with a lot of
new information.

If you are putting together a FAQ list, then I have some suggestions:
How important is it that bamboo is cut at the correct time of day (the
afternoon)?
How important is it that branches are left on the culm for a several
hours after cutting?

The practice in Thailand is generally to cut in the morning so that
the culms can be transported the same day. To make handling easier,
all branches are cut immediately after felling.

It would also be interesting to hear if borate treatment helps prevent
fungi, especially in tropical climates.

Scott

> 2009/2/27 guruprasad rane <ranegurupra...@gmail.com>

>
> > Dear Peeyush
>
> > 1. How is the bamboo likely to behave with time with respect to the effects
> > of this treatment method for exposed (roof elements) and covered (wattle and
> > daub) uses?
>
> > Bamboo is made up of mainly fibers and starch. Starch invites insects.
> > Fibers provide strength. Immersion treatments (Boric Acid & Borax) basically
> > dissolve the starch thus reducing the chances of insect attack. Copper
> > sulphate seems to make bamboo little fire resistant (I dont know How it
> > does). Roof elements might crack after prolong exposure to Sun and Rain.
> > Most of the cracks are small and on the upper layer of Bamboo thus the roof
> > may not leak due to craks. Performance of bamboo inside wattle & Daub Walls
> > mainly depends on the performance of plastering. As long as walls are dry
> > and free of insects it will last long.
>
> > 2. How does one best dispose off the solution after the treatment is over?
>
> > Let the tank dry out. Let the complete water evaporate then collect the
> > chemical powder and dispose it or keep it for further use.
>
> > Regards
> > Guruprasad Rane
> > Sr. Architect
> > Habitat Technology Group
> >www.habitattechnologygroup.org
>

> > 2009/2/19 Shyam K Paudel <spau...@inbar.int>

>
> >  Enquiry from a bamboo lover. Pls repond
>

> >> ----- Original Message ----- *From:* peeyush sekhsaria<psekhsa...@yahoo.co.uk>
> >> *To:* peeyush sekhsaria <psekhsa...@yahoo.co.uk>
> >> *Cc:* shyam paudel <spau...@inbar.int>
> >> *Sent:* Wednesday, February 18, 2009 7:52 PM
> >> *Subject:* life of bamboo treated by immersion

[senorpescado]

[purushothaman p]

Dear All,

This is not exact, however if I recollect boy-hood information, we immerse bamboo for three to four months(even more) in open irrigation wells and the bamboo would come for ten to fifteen years in open sheds... now a days, we are not using them, even in my professional life, I have not used bamboo.

further, I have started research on bamboo joints, could members direct me to good resource on it?

we are trying to develop portable (dismantle & re-erect) bamboo small unit structures as students(architectural & civil engineering) projects.

with warm regards,

P Purushothaman

Addl. Director, CUII, PMU

ella...@gmail.com

www.pmu.edu

[Oliver Frith]

Dear Peeyush,

 

Thanks for your questions. Regarding soaking methods of treatment – these are a fairly good way of treating bamboo without the need for investment in expensive equipment.

 

One issue the group might consider is that the use of holes on either side of the internode, while useful for helping diffusion in larger culms, can cause difficulties when you are trying to draw the solution out again. An alternative is to puncture the diaphragm with a long stick making holes of about 2 cm.

 

It is also interesting to hear they are drying the bamboo first. Usually freshly cut bamboos are treated as this aids diffusion of the solution.

 

If you are thinking of using bamboo in wattle and daub style applications – treating half split or quarter split bamboo would also speed up the treatment process and effectiveness (roughly a week, compared to at least double that for round culms).

 

For covered applications, treated bamboo should have a pretty decent life (20 plus years) – provided the treatment has been properly administered.  

 

For exposed applications, even with treatment the bamboo will likely degrade and you would probably need to change the roofing on a reasonably regular basis. Shingles are probably the best way to go. However, I would recommend not to use exposed bamboo – unless the design allows for protection against UV and rain (e.g. having a large overhanging roof to protect exposed bamboo exteriors). Obviously with roofs themselves exposure is not possible to mitigate against. In roofs, I would recommend bamboo for use in rafters – however, you would ideally need an experienced professional to support the team to make sure these were built in a safe way.

 

Regarding care and disposal of chemical solutions, there are a few main points:

 

1.       Definitely make sure that the tank is not in direct contact with the soil. Ideally they could be placed on a cement floor – or have plastic sheeting placed underneath them to avoid contamination through spillage

2.       Definitely make sure the treatment tanks are nowhere near a water source

3.       Even when drying the treated culm, which are stored vertically at first, make sure to have some sheeting to collect run off solution

4.       Sludge that builds up in the tank needs to be periodically cleaned as well, as it can stick to the surface of the bamboo causing potential health hazards – for water based preservatives, it is also possible to reclaim them from sludge by adding chromic acid

5.       When disposing of the waste – there should be regulations in your Country that govern where to do this. You should also consider that the treated bamboo should also be disposed of carefully at the end of its service life – either through incineration (this must be done at special facilities – using high temperatures) or at a waste disposal site.

 

Just to remind the group – INBAR also has a number of publications on its website, which are all freely available as downloads. Please always feel free to refer to this resource:

 

http://www.inbar.int/publications/?did=71

 

Best Wishes to everyone,

 

Mr. Oliver Frith
Programme Coordinator
Global Bamboo Construction Programme

 

International Network for Bamboo and Rattan (INBAR)
8, Futong Dong Da Jie, Wangjing, Chaoyang District
P. O. Box 100102-86, Beijing 100102, P. R. China
Tel: +86-13810563047
Fax: +86-10-64702166
Email: obf...@inbar.int
Website: www.inbar.int

 

In partnership for inclusive and green development 

 

----- Original Message -----

From: peeyush sekhsaria

To: peeyush sekhsaria

Cc: shyam paudel

Sent: Wednesday, February 18, 2009 7:52 PM

Subject: life of bamboo treated by immersion

 

I am trying my luck for the third time with this query on bamboo treatment by immersion. I have a couple of questions which hopefully may find an answer on this forum I am presently helping design a brochure on bamboo treatment as practiced by a group in Gujarat India. They treat their bamboo (bought dry from the local market) by immersion. They even out the bamboo at the nodes, drill holes on either side of each node and immerse it in a water based solution of  boric acid + copper sulphate and sodium bicarbonate. This method seems to have served them well and bamboo treated in 2001 are still doing well. They have been used for roofing - trusses and as wattle in wattle and daub walls that have been finished in lime render. My questions 1. How is the bamboo likely to behave with time with respect to the effects of this treatment method for exposed (roof elements) and covered (wattle and daub) uses 2. How does one best dispose off the solution after the treatment is over Thanking you Peeyush

 

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