1Hands-onChinese Style
Bamboo Furniture
Manual on bamboo furniture making
3Acknowledgement
This hands-on training manual is the outcome of the 'International Training Workshop on Furniture ProcessingTechnologies, held in Hainan, China, from October 13th to 24th 2003. It was jointly organised by the InternationalNetwork for Bamboo and Rattan (INBAR), the Ministry of Science and Technology of China (MOST), DeutscheGesellschaft Fur Technische Zusammenarbeit (GTZ) and International Farm Forestry Training Center, CAF.
Thanks are particularly due to Master Chen Yunhua for his excellent guidance and training during the workshop, as wellas to both his assistants, Mr. Yang yongqing and Ms. Fan yuequn. To Mr. Xu Zhangliang and Mr. Xu Huiliang fromHainan Global Bamboo and Rattan Product Co. Ltd, we wish to express our deep gratitude for providing thecomfortable venue and facilities.
We also wish to thank Ms. Wang Qinfang from the Sino-German Forestry Cooperation and Ms. Chen Yujie from theChinese Academy of Forestry, for their excellent support rendered to the workshop participants.
The Uttaranchal Bamboo and Fiber Development Board (UBFDB), we gratefully acknowledge for providing theauthors with their facilities during the compilation of this manual.
Most of the photographs included in this manual were taken by the authors during the workshop. Exceptions are thephotographs on page 11; page 12 (storage and drying); p. 13; p.14; p.15; p.16 (steeping) and p. 17, which were copiedfrom the Bamboo Preservation Compendium, by W. Liese and S. Kumar.
The authors.
5Traditional Chinese Furniture Making
The basic technique of traditionalfurniture making in China iscalled "YU".
This technique involves makinga bent mortise which ties thedifferent components togetherand forms a strong framework.
6Contents
Introduction
Durability measures2
Drying4
Preservation methods3
1Raw material selection
Processing culms5
8
9-10
11-12
13-17
18-19
20-24
7Assembling andFinishing
67
Additional designfeatures
8
Making furniturecomponents
ToolsAnnexure I
Culm ageAnnexure II
25-38
49-54
60-63
39-48
55-59
8The following chapters describe the sequence of theactivities involved in furniture making :
1. Raw material selection2. Preservation methods3. Drying4. Durability measures5. Processing culms6. Making components7. Assembling & Finishing8. Additional design features
Introduction
'The poor mans timber' in INDIA
'The friend of the people' in CHINA
'The brother' in VIETNAM
Bamboo is ...
Introduction
Bamboo has a long history as material in furniture making. Itis widely available in the developing countries as a strong,cheap and eco-friendly material. Bamboo furniture is elegant,light-weight and has a natural look.
9Raw material selectionBamboo culms used for furniture making are selectedaccording to the specific design requirements of thefurniture products. In general, middle or small sizedbamboo culms are used, that are straight and upright,with not so protruding nodes and without failures suchas lesions or insect holes.
Selection of material further occurs in accordance withrequired properties like strenght or flexibility that vary withdifferent furniture components. Accordingly we distinguishthree different component groups:
Structural components
Surface slath applications
Weaving
Raw material selection
For each of these the requiredproperties of bamboo culms aredescribed hereafter.
1
10
Properties: Thick-walled culmsof medium diameter. Thick wallsprovide strength and a highertolerance for nailing and drilling.
Suitable species:Arundinaria amabilis; Bambusabalcooa; Dendrocalamus bambusoides;Dendrocalamus latiflorus; Phyllostachyspubescens; Thyrsostachys siamensis
Required culm age: Matureculms, 3 to 4 year old, are mostappropriate as they combinestrenght with low moisturecontent and low shrinkage.
Properties: Bamboos withlonger internodes, that give longerslaths. Such bamboos usually havethinner walls.
Suitable species: Bambusa chungii;Bambusa nutans; Bambusa textilis;Bambusa tulda; Dendrocalamusgiganteus; D. hamiltonii; Melocannabaccifera; Neosinocalamus affinis
Required culm age: Matureculms, 3 to 4 year old, are mostappropriate as they combinestrenght with low moisturecontent and low shrinkage.
Properties: Young freshly cutculms with medium to longinternodes.
Suitable species: Bambusa chungii;B. textilis; Dendrocalamus giganteus;Neosinocalamus affinis; Melocannabaccifera; Phyllostachys bambusoides
Required culm age: Young, upto 1 year old culms are requiredas they contain a high moisturecontent for easy slivering.
Raw material selection
Surface slath applications WeavingStructural components
1
11
Durability measures
The durability of bamboo can be enhanced bytaking measures in the following stages:
Species selection
Harvesting
Storage
Drying
Manufacturing
Compared to timber, bamboo has a low naturaldurability. When used indoor as furniture, it may last 4to 7 years. Factors that reduce bamboo quality arecracks, splits and attacks by fungi and insects.
The durability of bamboo against these factors much dependson environmental conditions and its treatment from harvestonward.
2
Durability measures
12
Manufacturing
Nailing without pre-boring frequently results insplitting. Moreover, nailstend to become loose withtime and may alsocorrode. Both increase therisk of fungal attack.
Species selection
Generally, species with a high starchcontent are more susceptible to attackby fungi and insects.
Thick walled species are less likely to splitor crack when nailing or other fasteningtechniques are applied, which reducesthe risk of fungal or insect attack.
Harvesting
Harvesting culms duringthe rainy season and aftershooting may reduce therisk of fungal or insectattacks, as the culms have alower starch content.
2
Durability measures
Storage and drying
Culms should be stacked horizontallyover raised walls and off the ground,to facilitate water drainage and aircirculation. Preferably under a shed toprevent exposure to sunlight which maycause cracks. The latter often developwhen bamboo is dried too quickly.
13
The durability of bamboo culms can be significantlyimproved by using preservation methods. Thepreservation requirements vary from species to speciesand depend on the climatic conditions of the placewhere the product is made and used.
3There are two types of preservation methods: Traditional or non-chemical methodsThese methods are cheap and safe and can be carried withoutany special equipment. However, not much is known yet abouttheir effectiveness.
Chemical methods
Chemical methods are more effective than traditional methods,but not necessarily economical or feasible. Moreover, theirapplication may be hazardous to the user's health and theenvironment. In this section only some low-cost and relativelysafe methods are described.
Preservation methods
Preservation methods
14
Traditional preservation methods
Smoking chamber
The culms are cut at the baseand left leaning againstneighbouring ones for a fewdays until the crown has turnedyellow-brown . The culms areplaced off the ground.
Clumpcuring
Smoking The culms are exposed tosmoke by placing them overfire or by placing them in asmoking chamber for asuitable duration.
Principle Process
Through leaf transpiration, themoisture and starch content ofthe culm is brought down tominimize its susceptibility toinsect and fungal attack.
On exposure to smoke themoisture content is reduced,and a protective layer of tar isformed on the outer surfaceof the bamboo. Smoking alsoreduces splitting. All thesetogether reduce biologicalattacks.
Smoke darkened culmsPreservation methods
3
15
3Culms can also be painted witha mixture of tar and sand, orplaster, cow dung and lime, toprevent fungal and insectattack.
Lime washing
Soaking Freshly cut culms withruptured nodal walls aresubmerged in either stagnant orrunning water for 2 to 3months and then air-dried. Insome regions culms aresubmerged in salt water ormud.
Principle Process
Water leaches out the starchcontent of the culm, making itless attractive to certainorganisms. At the same timethe culm is effectively sealed offfrom these.
Culms are painted with slakedlime that is transformed intocalcium carbonate that inhibitswater absorption. The surfacebecomes alkaline which wardsoff fungal attack.
Plastered walls in CostaRicaPreservation methods
Soaking in water
Plastered walls in Costa Rica
16
Exposure to sulphur smokekills fungi and insects.
Care must be taken not to inhalethe sulphur smoke when opening thebag.
Butt end treatment
Chemical preservation
Steeping
Principle Process
Sulphursmoking
Bamboo culms are placed in asealed plastic bag with burningsulphur for 24 hours. Theculms turn a little whitishduring the process.
Culms of desired length, withbranches removed, areimmediately after harvestplaced upright in a containerof concentrated water-bornepreservative solution fordiffusion. Up to 25% of thebutt-end is kept immersed for7-14 days depending on culmlengths.
The sap is replaced by thechemical preservative solutionthrough diffusion.
Use a 10 to 15 % solution of boricacid and borax (50:50). This is aclean, odourless and cost-effectivewater-borne preservative, effectiveagainst fungi, termites and insectborers while posing little threat tohealth and environment.
Preservative methods
3Sulphur smoking
17
Soaking in Boric acid solution
Sap replacement method
Dripping preservation solution
3
Soaking
With a bicycle pump apreservative solution is forcedunder pressure through afreshly cut culm. Usually, whenthe outflow has reached 10%of the culm's volume (whichis equal to the vessel volumeof the culm), the treatment hasbeen accomplished.
Principle Process
The sap is replaced by achemical preservative solutionthrough diffusion.
Freshly cut branchless culmswith punctured nodal walls areweighed down in a containerprior to adding a water bornepreservative solution. Themethod takes at least 14 daysfor round culms.
The sap is replaced by achemical preservative solutionunder pressure.
In Costa Rica, a boron-based preservative (Menorel)has been successfully used,that also ser ves as afertilizer.
Preservative methods
Sap-replacement
18
DryingIf dried too quickly, bamboo will split and shrink around itssolid nodes. Cracks and splits will develop and lead tosubsequent deterioration by fungi and insects.
In this process the content of both starch and moistureis reduced. The method of drying varies with themarket requirements. If the product is used in a moistenvironment, the moisture content of the bambooshould be lower.
There are two basic methods for drying:
Traditional Drying
Commercial Drying
Drying
4
19
Traditional Drying
Drying by exposing the culms to natural air, preferrably undera shed, is traditionally practised in many countries. This is themost economical method. Drying depends on prevailingtemperature, relative humidity, and natural movement ofatmospheric air to which it is exposed. For local marketstraditional drying may suffice.
Commercial Drying
In this method drying occurs in a closed chamber or a buildingwhere the drying conditions (temperature, humidity, aircirculation and ventilation) can be controlled and maintainedat desired level. The drying time is influenced by the species,culm wall thickness, initial moisture content and portion ofthe culm. Grading of the culms before drying is thereforevery important. Drying is hastened by scraping the outer skin.
4
Drying
20
These are the processing treatments:
Checking for straightness
Straightening bamboo
Scraping skin
Removing outer nodes
Node punching
Sand filling
Heat bending
Cross cutting
Processing culms
As a raw material, bamboo culms have to undergo aseries of treatments before their actual application infurniture making. These collective treatments we callprocessing.
Processing culms
5
21
Apply heat with a blow torch,uniformily across the wholesection to be straightened. 5
Checking forstraightness
Bring the culm end to the eyefor alignment, to check forstraightness.
Roll the culm on a plane surface todetect posssible irregularities.
When applied How applied
Straightening
To check whether bending hasto be done for straighteningthe culm.
To ensure straight and uniformlines and curves in the furniturecomponents.
Apply the knife to remove athin layer of the culm skin. Useuse the knife back and forth fora uniform removal of outerskin.
In case the bamboo does nothave a clear skin, removing athin layer of the culm skinmakes it look nice and uniform.
Scraping skin
ProProcessing culms
22
Removingouter nodes
Apply a hand plane along thecircumference of the culmnode, making back and forthmovements while turning theculm with the other hand, toremove the protruding portionof the node.
Keep the marked part of thehand plane as well as the bladeedge against the node,perpendicular to the culmlength.
Outer nodes are shaved off inorder to get a uniformdiameter all along the culmlength.
When applied How applied
Puncture the inner nodal wallswith a long drill bit fixed on adrilling machine.
Nodepunching
In order to fill the whole culmwith sand, drilling through theinner nodal walls is required.
5
Processing culms
23
Culms are filled with sandbefore heat bending is applied,to prevent cracking andsplitting of the culm.
Plug one side of the culm. Thenfill the culm with sand while tap-ping on the floor to close thevoids.
Hole in the culm node
Plugging one end of the culm
When applied How applied
Sandfilling
Prior to making funiturecomponents the culms are cutto the desired lengths.
Cut the culms to desiredlengths using a saw.
The handsaw blade should alwaysbe right angled to the culm lengthwhile cutting
Crosscutting
5
Processing culms
24
Heat bending is done fortransformation of straightbamboo culms into desiredcurves.
1.Apply heat using a blow torch,in proximity to the portion to bebent.
2.Move the blow torch back andforth, so as not to crack thebamboo culm. Single point heatingshould be avoided.
3.Bend the culm by applyingforce on opposite ends.
4.Cool the bend of the culmwith water to fix the fibers, inorder to maintain its position.Cooling also serves to preventscorching.
5.Continue to apply heating andcooling till the desired curve hasbeen obtained.
When applied How applied
Heat bending
5
Processing culms
25
Leg poles
Stool leg supports
Mortise frame
Bamboo or wooden plugs
Surface supporting batterns
Bamboo nails
Surface strips
Concealing belt
Flattened Bamboo surface
Making furniture componentsAfter processing, the culms are used for makingfurniture components. All components used inChinese style furniture are listed hereafter.
6
Making furniture components
26
Leg poles
1.Cut the required numberof legs out of a single culm.Ensure that each leg pole has anode at one end for strengthreasons.
2.Check if all the pieces arevertically upright and equal inlength. Make both the cut endsperpenndicular to the culmlength.
Stool leg supports
* Refer to page 24
For this component culms need to be sand-filledso they can be subjected to heat bending. Leg sup-ports are added to the leg poles for extra strenght.They are applied in between the leg poles.
Apply heat bending* to the culms and check con-stantly for the right fit.
Leg poles are important components, as theysupport the entire furniture piece.
6
Making furniture components
27
Bent Mortise
A bent mortise is the basic element in chinese stylefurniture making which ties the other componentstogether and forms a strong framework.
Steps to make the bent mortise:
Determine the mortise groove length
Mark refernce lines on the culm
Make a template stick
Mark the culm
Cut the mortise grooves
Make the double pins
Apply heat bending to bend the mortise
Mortise Groove
Double pin 6
Making furniture components
28
An essential part of making the bent mortise is determining the length and position ofthe grooves to allow perfect positioning of the leg poles in these grooves. Apartfrom the circumference of the leg poles, the length of the groove depends on thenumber of leg poles. Accordingly we distinguish 3 different types of bent mortise:
Determine the mortise groove length
1. Cut a paper strip (1-2 cm wide) and fold itaround the leg pole with overlap.
2. Make a cut parallel to the culm length on theoverlap. The length of the obtained stripcorresponds with the circumference of the legpole. Cut on the overlap Strip matches circumference
The groove length in each case can bedetermined using the paper technique.Starting point of this technique is to make apaper strip that is equal in length to thecircumference of the leg pole. This is done intwo stages:
6
Making furniture components
Triangular (3 legs) Square (4 legs) Pentagonal (5 legs)
29
Step by step we will now adjust the length of the strip tothe groove length, for each of the three types of bentmortise.
Triangular bent mortisewith leg poles
Groove length is 3a'
3 1 2
1/4 1/4
a a'
Calculations:1(aa') - 1/4(2a') = 3/4 (a2)3/4(a2) : 2 = 3/8 (a3)1/2(a1) - 3/8(a3) = 1/8 (31)1/8(31) + 1/4(12) + 1/4(2a') = 5/8(3a')
Inference: the required length of the strip is 5/8 th of the original strip.
Triangular bent mortise
The following steps are required:
Step 1Fold the strip into half to make foldline 1.Step 2Fold the right half into two quarters to make foldline 2.Step 3Make the left end meet fold line 2 and cut through thenew fold line 3.ResultThe longer part of the strip corresponds to the correctgroove length of a triangular mortise.
Step 1
Start
Step 2
Step 3
Result
6
Making furniture components
30
Square bent mortise
The following steps are required:
Step 1Fold the strip into half to make foldline 1Step 2Fold the right half into two quarters to make foldline 2Step 3Fold the right quarter into two eighth to make foldline 3Step 4Make the left end meet fold line 3 cut through the newfoldline 4ResultThe longer part of the strip corresponds to the correctgroove length to make a square mortise.
a'
Groove length =4a'
1/4 1/8 1/8
1 2 34a
Calculations:
1(aa') - 1/8(3a') = 7/8 (a3)7/8(a3) : 2 = 7/16 (a4)1/2(a1) - 7/16(a4) = 1/16 (41)1/16(41) + 1/4(12) + 1/8(23) + 1/8(3a') = 9/16 (4a')
Inference: the required length of the strip is 9/16 th of the original strip.
Step 1
Start
Step 2
Step 4
Step 3
Result
Square bent mortise
6
Making furniture components
31
Pentagon bent mortise
The following steps are required:
Step 1Fold the strip into half to make foldline 1.Step 2Fold the right half into two quarters to make foldline 2.Step 3Fold the right quarter into one eighth to make foldline 3.Step4Fold the right eighth part into one sixteenth parts.Step 5Make the left end meet fold line 4 and cut through thenew foldline 5ResultThe longer part of the strip corresponds to the correctgroove length to make a pentagon mortise.
Calculations:
1(aa' )- 1/16(4a') = 15/16 (a4)15/16(a4) : 2 = 15/32 (a5)1/2 -15/32(a5) = 1/32 (51)1/32(51) + 1/4(12) + 1/8(23) + 1/16(34) + 1/16(4a') = 29/32(5a')Inference: the required length of the strip is 29/32 th of the original strip.
Pentagonal bent mortise
Step 1
Start
Step 2
Step 4
Step 3
Result
6
Making furniture components
2 3
Groove length is 5a'
45
1/32 1/4 1/8 1/16 1/16
1 a'
Step 5
a
32
Make a template stickMark the groove length on a bamboostrip using the paper strip. The length ofthis template stick should be equal to thelength of the groove plus the distancein-between two grooves.
Mark reference linesMark a reference line by scraping astraight line along the culm length. Oneither side of it, two parallel lines aremarked, at a distance of two thirds ofthe culm diameter from the first one.
Mark the culmUsing this template stick, mark the culmalong the central reference line. Make surethe mortise grooves do not lie on a node.The distance between two groovesshould be marked on both ends of theculm.
culm showing thereference lines
Marked grooves on the culm (triangular mortise)
Template stick6
Making furniture components
33
Cut the grooves
Groove
Culm baseCutting outside
marking
Cutting outsidemarking
Cutting adjustments (view from above)
Culm end
Cutting insidemarking
Cutting insidemarking
Cutting over marking
Cutting overmarking
Groove Groove
Make sure the blade of the saw isperpendicular to the culm and thecentral reference line.
2.Insert a pointed knife in between the lowerends of both cuts and twist the blade slightly tobreak the culm open.
1.Make a cut half the culm diameter on thegroove markings. Cut just outside the marking atthe culm base, cut just inside the marking at theculm end and cut exactly over the groove markingsin the middle of the culm. This is done to neutralizethe differences in wall thickness.
6
Making furniture components
34
3.Make the groove corners round, meeting the3/5th of the culm diameter, using the referencelines as guidelines.
4.Remove material from themortise grooves in two stages:
a. Perpendicular to groove length on either ends
b. Along the culm lengtha. b.
6
Making furniture components
35
In order to make the joint for the bentmortise, at both culm ends a pin is madein three steps:
Make the joint pins 1.Make a cut at half the distanceto the groove on one extreme ofthe bent mortise. The cut must bemade perpendicular to the planeof the groove, three-fifth of theculm diameter deep. Repeat thisfor the other culm end, but inopposite direction.
2.Remove the upper 3/5th ofthe culm section by splitting itperpendicular to the previous cut.
3. Taper both ends to make apin.
Opposite ends of the bent mortise
Making furniture components
6Lower part
removed
Upper partremoved
36
Chisel a plug from either a thick walledbamboo or a piece of wood, that tightlyfits in the cavity of the leg poles onhammering.
Bamboo or wooden plugs
Take a culm of approximately 8-10 mmwall thickness and cut strips of desiredlength and width.
Surface supporting batterns
Making furniture components
6
37
Bamboo nailsSplit a thin-walled culm into squaresections of which the size dependson the application. Chisel and taperto get a nearly pointed end.
Surface stripsMake incisions at equal intervals inthe culm end so as to get strips ofrequired width. Tear the strips apartas shown in the image.
Concealing belt
Split a thin-walled culm to make along strip of bamboo. Remove thewhite material to make it moreflexible.
The purpose of a concealing belt isto cover any unattractive parts ofthe furniture piece.
concealingbelt
Making furniture components
6
38
Crushed bamboo surface
1.Split the culm in 2 halves. Remove the inner nodesand put the halves on the ground with the opened sidedown. Make multiple slits using an axe, starting fromone end of the culm. While crushing, move towardsthe middle of the culm. Then start at other end, mak-ing sure that the starting point of the slit is not in linewith the slits made from the other side.
3.Cut the crushed bamboosurface into desired shape andsize for their application.
2.After making the bambooflat, glue it to a veneer ply.
Making furniture components
6
39
Fix the leg poles
Fix the supporting legs
Fix the supporting batterns
Place the surface strips
Frame the seat surface
Apply the concealing belt
Quality check & finishing
Assembling & FinishingIn this section a stool is assembled that incorporates allbasic skills and techniques of Chinese style furnituremaking.
Assembling & Finishing
7
40
Fix the leg poles
1.Apply heat from the inner side of thegroove till it becomes bendable. Positionthe leg pole in the groove and bend themortise around it. Maintain the position byapplying water to cool and to fix thatposition. Repeat this for the remaining legpoles.
2.Now position all the leg poles in thebent grooves one by one. Bring the twoopposite ends of the culm together to closethe mortise frame.
3.See if the frame allows the joint to befixed and check the geometry. Makeadjustments if required by sawing, to relaxtension between mortise and leg poles.
7
Assembling & Finishing
41
4.Mark and drill a hole in both rearlegs to match the joint pins. Make surenot to drill through the whole culm,but only through one wall.
5.Insert the pins and adjust theframe position to suit the requiredgeometry.
6.Drill one or two holes through thepin joint in order to fix them withbamboo nails.Chop off the nail parts that are stickingout.
Bent mortise with leg poles
7
Assembling & Finishing
42
7.After ensuring that a perfect geometry(with right angles) has been achieved, abamboo plug is inserted and hammeredinto the cavity of each leg pole. The extraportion is cut with a saw blade.
7
Assembling & Finishing
43
Fix the supporting poles
1.Apply heat bending to fit all 4supporting poles on each side of thestool, as shown in the image.
2.Position the support pole betweentwo leg poles and then drill a hole throughboth of them exactly in the middle. Fixthem by applying a bamboo nail.Then, nail both sides of the supportingpole to the corresponding leg pole, alsofrom the middle.
3.Saw the surplus length of thesupport pole diagonally so as onlythe leg poles touch the ground.
7
Assembling & Finishing
44
Fix the batterns
Fix the batterns to the frame using nails,preferrably made of bamboo.
Place the surface strips
Place the surface strips across the batterns andfix them with nails or weave them togetherwith fiber. Cut any surplus material.
Assembling & Finishing
7
45
Frame the seat surface
1.Place four strips outlining thesurface seat with crossing ends. Fixeach strip to the structure from thecenter of each side.
2.Cut the corner overlapsdiagonally to get a perfect seam.
Assembling & Finishing
7
46
Fix the concealing belt
1.Fix the concealing belt to one sideof the stool. Remove some whitematerial from the inner side of the beltto allow bending around the corners.
2.Then apply heat and bend thebelt along the adjecent side and fixit with nails.
3.Continue the process for all thecorners, to end with an overlap. Cutthe belt on the overlap in the centreand fix the ends with nails.
7
Assembling & Finishing
47
Quality check & FinishingAfter assembly, the products must be checked forquality and modified if required. After that, finishingis done. These two stages combined, guaranteesafety for the user and result in a higher percievedvalue of the end product.
Quality Check
Check for any irregularitiesCheck for any splinters, protruding nails, cracksand unwanted cavities
Check for perfect symmetryCheck if all the leg poles have the same length, bymeans of a string, as shown in the images. Alsomake sure that all angles are equal.
Check for solid sound on impactDrop the furniture on the floor to hear a singlesolid sound which indicates the components arewell assembled.
Check for structural strengthApply load on the furniture and check for thestrength of all the components.
7
Assembling & Finishing
extra material has tobe taken out
Check the symmetry with a string..
Remove surplus material
Applyload tocheck forstrength
48
Remove surplus materialChisel off any protruding material toget a smooth surface.
Heat blowing & cleaningUsing a blow torch, burn and removeall the tiny bamboo hair.
LacqueringRemove dust or any other impuritybefore applying the lacquer using abrush.
Filling cavitiesUse a mix of sawdust and glue to fillin any cracks or unwanted cavities
SandingUse rough sandpaper for removingsurplus material and use fine sandpaperfor smoothening surfaces.
Finishing
7
Assembling & Finishing
49
Additional design features
Having covered the basics skills and techniques of Chinesestyle furniture making, in this section we show some additionalapplications and design features, based on a chair design.
C-joint
Supporting polesMultiple mortise
Seat surface
Backrest supportBack restFlat spokes
Pin joint
U-joint
Additional design features
8
50
Back rest & back rest support
1 2 3
5 6 7
4
In this chair design, the back rest continues into the rear legpoles, made of one solid culm piece. This design requiresgood skills in heat bending, the stages of which are shownhereafter in the right sequence. The same sequence appliesfor making the back rest support.
Additional design features
8
51
Joinery
Pin joint
Two pins are made on one culm end to fita rectangular groove on the other culm.
Plugging joint
A plug is inserted in the tube to be jointedand a hole is drilled through it. Then theother part is drilled and the joint is fixedby applying a nail.
U-cut joint
A deep U- Cut is made at both ends ofthe culm to be fitted around another culm.
Additional design features
8
52
C-shaped joints
A culm is sharpened to a point to fit aC-shaped cavity in another culm.
Flat spokes
Flat spokes are made of flat bamboostrips and pointed at both ends. They arevertically fixed by sticking the points indrill holes. At seat level these drills aremade in a tube, with corresponding holesmade on the underside of the back restpole.
Additional design features
8
53
Round spokesRound spokes are made of small-sizedculms shaped by applying heat bending.They fit in holes drilled with a hole sawbit on the underside of the backrest pole.With their base, the spokes rest in a longgroove made in the spoke support, po-sitioned on the seat surface. 1 2
3 4Multipe mortises
For furniture pieces that require morestength, two or more mortise bents canbe applied. In that case, it is importantto keep the joints on alternating sides ofthe furniture piece.
Additional design features
8
54
8
Additional design features
Applications of a multiplemortise bent...
Alternative application ofa single mortise bent...
55
Tools
Hand plane
Use: scraping outer nodes of culms.
V-shaped knife
Use: splitting bamboo culms from the ends.
Pointed knife
Use: inserting culms for precise splitting.
Annexure I
Annexure I
ANNEXURE I
56
Mallet
Use: scraping material from the insideof the culm.
Wood saw
Use: cutting portions of the culm
Chinese Hacksaw
Use: cross cutting of the culm
Ann
exur
e I
Annexure I
57
Axe
Use: making flattened bamboo by crushinground culms.
Torch
Use: applying heat to the culm tofacilitate bending.
Jig
Use: molding culms into desired shape.
Annexure I
Annexure I
58
HammerUse: applying nails.
PlierUse: extracting nails andstaples.
ChiselUse: removing surplus mate-rial from the inside of theculm.
Drill bitUse: special diamond shapedbit to pierce bamboo culmswithout splitting.
BrushUse: applying water duringheat bending to fix the bendposition and avoid scorching.
Sand containerUse: filling culms with sandprior to heat bending.
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PencilUse: marking on the culmwhere cuts and drills are tobe made.AdhesiveUse: glueing.
PencilUse: marking on the culmwhere cuts and drills are tobe made.
Staple gunUse: quick nailing of bambooparts.
SandpaperUse: to finish a surface tosmoothen.
Steel RuleUse: measurement.
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ANNEXURE II
Culm AgeIt is impossible to make a presize estimation of theage of a bamboo culm, unless it was marked afterappearing as a shoot. There are no indicators with areliability comparable to that of growth rings in trees.
In the following, six culm characteristics are listed, forthree different age categories. The indicated changesover ageing are similar for most species. However,their reliability as age indicator is limited as differencesbetween species can be big. If more characteristics areconsidered, the age estimation is more reliable.
Bamboo fibre colour
Young bamboo culms have white fibres, indicating ahigh water content. The fibres become more yellowishas they age.
old
Young
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Branching
Fir
Emerald or dark green
Internode cover
Culm age < 1 year 1 - 2 years > 2 years
Green Turning into yellow
Internode color
Often covered with tinywhite hairs or flour Flour is falling off No flour left
Culm age < 1 year 1 - 2 years > 2 years
All the pictures were taken in astand of Dendrocalamuslatiflorus. Other species mayshow differences in characteristicsand in their changes over agecategories.
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Internode epiphytes
None Lichen and epiphytesare found
None
All or almost allsheaths are kept
Culm sheaths
None are left
Culm age < 1 year 1 - 2 years > 2 years
Culm age < 1 year > 1 yearsAnnexure II
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Branching has justbegun. Branches feelsoft.
Secondary branchesstart growing, they arelightly coloured andnot tough
Branches arebecoming tougherand colour is turninginto yellow-greenBranching
Remaining part fallsoff
Whole sheath ring orpart of it is kept
Remaining partbecomes harder
Sheath ring at node
Culm age < 1 year 1 - 2 years > 2 years
Culm age < 1 year 1 - 2 years > 2 yearsAnnexure II
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