Turn solid wood in­to a cont­in­u­ous fiber

To make a mono­fil­a­ment from wood, we need very long pie­ces that are ex­treme­ly small in di­am­e­ter and high­ly flex­i­ble. Build­ing on the knowl­edge of bas­ket­mak­ers, we are us­ing split wil­low with­es as our raw ma­te­rial. Th­ese are fine strips about 1.5 m long that are ir­reg­u­lar in cross-sec­tion, mea­sur­ing up to 7 mm wide and 1 mm thick. They are ob­tained from whole with­es us­ing a man­u­al or mech­anized cutt­ing de­vice that spl­its them off from the out­er sur­face of the branch. This pro­duces strips with a flat un­der­side and curved up­per side. The up­per side is the peeled but other­wise un­da­m­aged sur­face of the withe. It is left in­tact, as it can with­s­tand greater stress­es than wood whose fibers have been opened up by pro­cess­ing.

The struc­ture of wil­low wood, with its long cells and long fibers, con­tributes to this unu­su­al flex­i­bil­i­ty, as does the fact that the wood in the fast-grow­ing with­es is na­t­u­ral­ly quite young. Whereas struc­tu­ral lum­ber must be la­bo­ri­ous­ly steamed and com­pressed to in­crease its flex­i­bil­i­ty, sim­p­ly be­ing im­mersed in wa­ter is suf­fi­cient for wil­low. The tra­di­tio­n­al mod­i­fi­ca­tion pro­cess­es for wood can al­so be used on wil­low to fur­ther in­crease its flex­i­bil­i­ty. Wil­low with­es are typ­i­cal­ly stripped of their bark be­fore use, re­veal­ing a pleas­ing aes­thet­ic of smooth, light-col­ored wood with fine pores. Wil­lows grow in moist soils such as flood­plains. Most wil­low grown com­mer­cial­ly for wider dis­tri­bu­tion is cul­ti­vat­ed in Spain, Po­land, and France, but there are many small­er plant­ings through­out Eu­rope for re­gio­n­al con­sump­tion. In­creased use of wil­low for wood-based tex­tiles could thus of­fer Eu­ro­pean farm­ers an op­por­tu­ni­ty to tap in­to new mar­kets.

The qual­i­ties of a tex­tile are great­ly in­flu­enced by the cross-sec­tio­n­al shape of the fibers from which it is made. The more thor­ough­ly uni­form this shape is, the more pre­cise­ly the char­ac­teris­tics of the fiber and the tex­tile can be spe­c­i­fied. To pro­duce solid-wood mono­fil­a­ments with spe­cif­ic cross-sec­tio­n­al shapes, we have adapt­ed com­mon pro­cess­es for mod­i­fy­ing the width and thick­ness of wood. The chal­lenge here is that the split with­es to be mod­i­fied, like the mono­fil­a­ments to be cre­at­ed, are very small in di­am­e­ter. The small­er the piece is, the greater the im­pact of the ma­te­rial’s na­t­u­ral­ly oc­cur­ring ir­reg­u­lar­i­ties and the idiosyn­crasies of its grain. This means that ex­treme­ly pre­cise tools and metic­u­lous­ly uni­form han­dling of the work­piece are re­quired to pro­duce a cross-sec­tio­n­al shape that is con­sis­tent for the en­tire (ef­fec­tive­ly end­less) length of the mono­fil­a­ment. How­ev­er, with skill­ful tech­nique, a piece that is ex­ceed­ing­ly tiny in cross-sec­tion but al­so very long – unu­su­al pro­por­tions for wood­work­ing – can be re­li­ab­ly ob­tained from this pli­able ma­te­rial.

De­vel­op­ment is a pro­cess of it­er­a­tion over artis­tic, ar­ti­sa­nal, struc­tu­ral-en­gi­neer­ing and me­chan­i­cal-en­gi­neer­ing ap­proach­es. We use DIY meth­ods to build our own high-tech, low-bud­get machines and put them im­me­di­ate­ly to use. This al­lows us to ar­rive at a proof of con­cept via ex­treme­ly short de­vel­op­ment cy­cles. Refin­ing our pro­cess­ing meth­ods and machines in tan­dem with the new ma­te­rial we are in­vesti­gat­ing is a great ad­van­tage to our de­vel­op­ment pro­cess, since tools and ma­te­rials have a pow­er­ful in­flu­ence on one another. By tak­ing this du­al­i­ty in­to con­sid­er­a­tion at a very ear­ly stage of de­vel­op­ment, we can tight­ly con­trol both the con­di­tions un­der which our pro­cess­es and meth­ods are ex­e­cut­ed and the de­sign pos­si­bil­i­ties of the ma­te­rial un­der de­vel­op­ment.

The re­search pro­ject FLIGNUM – A solid-wood mono­fil­a­ment is car­ried out by

For­schungs­­plat­t­­form BAU KUNST ER­FIN­­DEN | Prof. Hei­ke Kluss­­mann | Lei­tung|
St­e­f­­fi Sil­ber­­mann, Jan Ju­ra­schek, Arne Dohr­mann, Le­na Hell­mann, Till Ihrig, Mah­yar Jalali, Cla­ris­sa Rauch, Ma­ria Va­sen­i­­na, Li­sa Sch­rei­ber, Ju­li­us Abro­m­eit, Sel­se­la Kho­ra­sa­ni

FG Ex­pe­ri­­men­tel­les und Di­gi­­ta­les Kon­stru­ie­ren und En­t­w­er­fen | Prof. Phi­l­ipp

FG Tren­­nen­de und Fü­­gen­de Fer­­ti­­gungs­ver­­fah­ren | Prof. Dr.-Ing. Prof. h.c. Ste­­fan Böhm

FLIGNUM is fund­ed by the FNR - Förder­a­gen­tur nachwach­sende Roh­stoffe e.V.


research & project funding