Industrial Hemp Bow Backing.

[greybeard]

Has anyone tried natural hemp fibre as an alternative backing for selfbows?

Being a natural plant fibre it should be compatible with PVA type glues.

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Ecru/Undyed/Natural Hemp roving (combed top), spinning fibre - 4 ounces $10.54 AUD., may seem expensive but would depend on coverage.

I can’t find a price on the plumber’s hemp, for some reason the plumbing supply shops in S E Q do not list it on their websites.

I believe that hemp is virtually a non stretch fibre and if so could overpower the belly of the bow.

Daryl.

[cmoore]

Looks like it'd make a great backing, couldn't be any less stretchy than sinew or fibreglass so I dont think over powering the belly would be an issue, might even add a pound or two on the draw weight

[DrAK DaRippa]

i've never used natural hemp fibre before, but i did remember reading this book online..

http://www.archerylibrary.com/books/gal ... r04-1.html

"The other material of which strings are made is hemp, and this is of two kinds, male and female. The male is thick and coarse, and consequently is worthless for bow strings. The female sort is good, but it must be carefully picked and very well chosen. A good string should be gummed and not glued. The loop should be as small as possible, and well stretched with a stone weight (etendue fort a bonnes pierres de fais). And if you wish to know if a string is good, untwist the middle of it, and if the three strands are separate and distinct, it is a good one, provided always that when the string is twisted up again, it is hard and firm, for the harder it is, the better it will be."


so the two things to draw from that might be finding what gender of hemp they are selling, and secondly the part saying to pre stretch it, is probably good for something supposed to be a backing.

as for the belly issue i haven't the foggiest.

i'd like to get some hemp for spinning though, i've tried to process hemp stalks into fibres by hand and it's tedious

[GrahameA]

Morning All.

.... and if the three strands are separate and distinct, it is a good one, provided always that when the string is twisted up again, it is hard and firm, for the harder it is, the better it will be."...

... i'd like to get some hemp for spinning though, i've tried to process hemp stalks into fibres by hand and it's tedious

If you want to make hemp bowstrings you will find it easier to make small ropes. Make yourself a miniature rope making machine.

Hemp was used for lots of things it has been superseded by synthetics. However, if your are bailing wool synthetic thread for sowing the bail is not a good choice - the fabric mill will not like you. Whilst hemp is refereed to as non-stretch it does just not very much which is why it is good for mooring ropes. Not all hemp is made from hemp - eg manilla hemp is made from a bannana species.

Did you ret your hemp stalks before you started to process them to break down the pith??? Just like flax for linen.

[greybeard]

Not all hemp is made from hemp - eg manilla hemp is made from a bannana species.

"The fibre known worldwide as Manila hemp from leaf sheath of plant Musa textilis nee indigenous to the Philippines; similar to banana plant strongest among natural fibres, with fibre length from 3 to 9 feet or more."

A good fibre length for backing bows.

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Abaca Farming In Rapu Rapu Island.jpg (117.79 KiB) Viewed 4069 times

Daryl.

[perry]

I have not used Hemp Fibres but Jute String and Jute Upholstery Webbing to back Bows. Applying the Jute String was PAINFULL, 1 Strand at a time really tried my Patience. It is a very good Bow Backing. Jute Upholstery Webbing proved easy to apply and highly effective as a Bow Backing. I Soaked the Webbing with watered down Bondcrete then squeezed the excess out. Then Primed the Back of the Bow with straight Bondcrete. I let it tack off a little and then placed the Webbing Strip on one end, I bound it in place and then pulled it tight to the other end of the Bow, bound it in place and then wrapped the lot in a stretchy Bandage to hold it in Place. It does increase the amount of Compression the Belly is subjected to and in my opinion a wider cross section is required. It does not add Draw Weight. You will not have a Tension Failure with a Vegie Fibre Backing like Jute or Hemp.

You can Sand it down after a couple of Weeks drying to reduce Mass. Because of the Weave you can paint it, sand it unevenly, paint again, sand in adjacent regions and so on to achieve a Snake Skin like Pattern as each layer of Paint fills newly exposed Voids in the Weave

I am aware that Plumbers Hemp makes an excellent Backing and is applied in a similar fashion to Sinew, in that it is Soaked in Glue, excess squeezed out and then layed in overlapping Layers. Like the Webbing it can be Sanded when Dry. I guess if you are keen enough and can find some you could Tease out a Length of Hemp Rope. Maybe Hornmaster could source some for you as he uses Vegie Fibre as Tinder with his Flint Striker Kits. Muzzleloaders use Flax Fibres for Tow also, maybe another source of Vegie Fibre Bow Backing.

Daryl I have plenty of Jute Upholstery Webbing, happy to give you some next I see you.

regards Perry

[yeoman]

It is also my understanding that hemp is very low stretch. This in addition to its very high tensile strength means it could/can overpower the belly. Tim Baker reports just this phenomenon on a number of bows. If you could get the raw fiber, I think it'd make for a very good backing, even one layer thick.

Sinew is actually quite stretchy. It elongates about 4% before breaking. This is quite a bit more than wood, which in an exceptional specimen will have a tensile strain of about 1%.

What do plumbers use hemp for?

[morganp]

What do plumbers use hemp for?

When I was a builder decades ago, in the sixties and seventies in fact, all plumbers used hemp. So did chippies and brickies. They would smoke it, the mature female plant being best. But if the foreman got at them they would retreat to the bowels of the building and work for a while, using the hemp fibre, with grease of some kind, as a joint packing/wrapping material. That is pipe joints. And no, 'pipe joints' are not 'bongs'. Although one sideline for plumbers was making nifty little pipes for hemp (female) from various brass and stainless fittings. They were very happy building sites and people hardly ever fell off the scaff.

[greybeard]

What do plumbers use hemp for?

Dave,

The application I remember most was to seal the threaded joins/angles and installing taps when using galvanised water pipe, it was used in a similar manner to the way plumbers tape is used today.

Also it was used to hold fibrous plaster ceilings in place.

Daryl.

[yeoman]

Aha.

If I could get my hands on some, I'd love to give it a try. I'd even back a small sample (or a few, in the interests of scientific thoroughness) and subject them to rigorous bend tests. This would identify how strong in tension it is and how thick might be sufficient for backing a bow.

[rodlonq]

Dave, maybe this link might be worth a look.

http://www.cadia.com.au/plumbers-hemp

Cheers.... Rod

[greybeard]

I managed to obtain a few metres of plumbers’ hemp from a local plumber.

At first I thought there were definite possibilities for this fibre as a backing material for bows but when I started teasing out the fibres the moments of joy started to diminish.

As the teasing process went on I started to get shorter fibres piling up, at the rate this was happening it would not be long before the workbench top would start to resemble a barber shop floor.

Although not impossible I believe it would be very time consuming to try to successfully apply these loose fibres to a bow. The fibres are probably a little finer than human hair.

Plumbers Hemp Teased.JPG (142.84 KiB) Viewed 4003 times

If I could get my hands on some, I'd love to give it a try. bend tests.

Dave, if you would like some to try pm a delivery address.

Daryl.

[yeoman]

One of the reasons hemp is very good is because in the plant, the individual fibers can be almost as long as the plant, as opposed to say cotton which has very short fibers.

It's a little disappointing to see plumber's hemp appears to be made from tow.

Is it like that along the whole length of the rope? If so, I think I will skip the tests.

[greybeard]

Is it like that along the whole length of the rope? If so, I think I will skip the tests.

Unfortunately yes, I think the extremely long fibres are broken down during processing.

An alternative is to cut down some banana plants.

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"The stalk of a banana plant contains fibrous strands that can be processed into anything from paper to fabric similar to kimono grade silk."


Daryl.

[rodlonq]

Hi Daryl,

Manila hemp seems to be a great candidate for backing. It appears to have very high tensile strength and stiffness.

ManilaHempCurve.png (146.03 KiB) Viewed 3967 times

Haven't been able to find a source for the raw fibres like you pictured above.

Cheers..... Rod

[greybeard]

Rod, it appears that a lot of the information on natural fibres generalized and not specific.

I believe that the fibres strength increases during processing as unwanted plant material that binds the fibres together is removed, the end result being pure cellulose fibre.

For the purpose of backing bows we probably require fibre that has had minimal processing which yields fibres of a manageable length but with the result of a weaker fibre.

Daryl.

A short read for those interested in natural fibres.

http://www.fao.org/economic/futurefibre ... abaca0/en/