How tight do you stretch webbing

[Arron]

Hi. Does anyone know a rule of thumb for how tight to stretch elastic webbing.

I'm doing a dining chair which is just elastic webbing, then foam rubber - for seat and back. I don't want it going soft in a few years time but I don't want to overstretch it, if that is possible.

A Google search reveals a few answers for jute webbing, sprung seats and some type of elastic webbing which is held In by clips. I don't think any of those are relevant.

Cheers
Arron

[shanesmith80]

I used jute webbing for my chair. Worked well. I guess it would depend on how stretchy the elastic is. What sort of elastic is it? This is more out of curiosity than anything.

[Arron]

I used jute webbing for my chair. Worked well. I guess it would depend on how stretchy the elastic is. What sort of elastic is it? This is more out of curiosity than anything.

DIY Upholstery Supplies - Elastic Webbing Premium Grade for seating (http://www.diyupholsterysupplies.com.au/home/component/virtuemart/?page=shop.product_details&flypage=flypage.tpl&product_id=1878&category_id=30)

[Xanthorrhoeas]

I am only a learner upholsterer so I have no actual experience here. But, what I do with a new product or technique is go to the basic materials science. Our culture uses the term elastic for rubber and rubber based products, but rubber is actually inelastic. Confused? That is because the term elastic means something like "will return to exact original dimensions after deformation" and rubber never does that - any deformation has a long-lasting effect (small though it may seem at the time). Strangely enough steel and concrete structures are elastic, but rubber is not. Glass is elastic within strict limits (as well as being a super-cooled liquid so it slumps with time).

OK science lesson over - what does it mean? It means that you should not over-tighten anything rubber based. What that indicates to me is that you should get the straps taut but not really tight or you will shorten their lives significantly. Just think about "elastic" rubber bands - if you stretch them tight they break or deform and they never return to shape.

Also, rubber oxidises or perishes and the further you stretch it the more minute cracks open and expose the inner rubber to oxygen and oxidisation.

I hope this helps

David

[Xanthorrhoeas]

I also have some mid-century-modern Australian chairs that have rubber webbing straps to do for my son and daughter-in-law . The perished straps on their chairs are attached with tacks, but, as far as I can see, the new equivalent of these is the straps with metal clips at each end. At least, the strapping looks to be identical. My intention is to follow the instructions for the straps with metal ends. Those make clear that only minimal force is to be used so that the straps are not overstretched, probably for the reasons that I have given above.

[neilb]

I am a retired upholsterer and have done many hundreds of pieces of furniture requiring different types of webbing. The elastic webbing you are referring to is either back or seat webbing. Back elastic webbing is much more stretchy than seat webbing and should not be used for seating. It just will not last. Elastic seat webbing is much firmer. Both can be bought at Clarke Rubber or a local upholsterer. Also you MUST sand smooth ALL surfaces where the webbing touches the framing to avoid premature wearing and fraying of the webs. This applies to ALL types of webbing. As far as the amount of stretch used for seating - pull it till you have about 75% of the stretch available or to the required tension. Do NOT pull it to the max stretch unless you are using Jute webbing which must be pulled to the max using a special webbing puller. Hope this sorts out your stretch problem.

[Arron]

I am a retired upholsterer and have done many hundreds of pieces of furniture requiring different types of webbing. The elastic webbing you are referring to is either back or seat webbing. Back elastic webbing is much more stretchy than seat webbing and should not be used for seating. It just will not last. Elastic seat webbing is much firmer. Both can be bought at Clarke Rubber or a local upholsterer. Also you MUST sand smooth ALL surfaces where the webbing touches the framing to avoid premature wearing and fraying of the webs. This applies to ALL types of webbing. As far as the amount of stretch used for seating - pull it till you have about 75% of the stretch available or to the required tension. Do NOT pull it to the max stretch unless you are using Jute webbing which must be pulled to the max using a special webbing puller. Hope this sorts out your stretch problem.

Fantastic, I knew there would be one of you guys around who would read it eventually!

The webbing I have is seat webbing - or at least that's what I asked the dealer for. I also used it for the back, which was my mistake, but it doesn't matter as this exercise was primarily a learning experience.

Now my understanding of what you are saying is that if I fix the elastic webbing on one end, then stretch it to the max (a good muscular stretch but not going overboard), then let it go back by about 25% of the amount of the stretch - then I should have it about right. Fortunately that's pretty much what I did, but the problem is I used a webbing stretcher, so the amount of stretch I got out of it is more then if I had pulled it manually. Do you think I have overstretched it ?

Cheers, and thanks for taking the time to reply
Arron

Ps. Good tip on Clarke rubber for webbing. I never thought of them.

[fletty]

I do the same as neilb even to the extent of routing a large radius on any timber edge that the webbing passes over. I am also constantly surprised by the addition to the tension caused by the friction at the woven junctions of the webbing. I repaired a chair once where the webbing wasn't 'woven' but just left as 2 independent layers. I had to re-use the existing webbing and so I left one layer attached and wove the other layer through the first. The increase in tension and comfort was amazing!
fletty