Archive for February 20th, 2010

Backed Fabrics

Weekly weaving class with Liz Calnan at the NSW Handweavers and Spinners Guild started up again last week after the summer break. Our first topic is Backed Fabrics.

Nisbet’s definition (Grammar of Textile Design, available here on the
On-Line Digital Archive of Documents on Weaving and Related Topics):

“Backed” fabrics are characterised by an additional series either of warp or weft threads employed for the purpose of increasing their strength, weight, bulk and warmth, or any one of those properties, without affecting their surface appearance”.

It seems traditional industrial use was to use cheaper/coarser/inferior quality threads, hidden on the back of the cloth, in very practical applications such as men’s clothing.

Liz had photos and student samples using the technique to showcase and make the most of some of the fancy and often heavier yarns now available. You can give them the space to shine without sacrificing stability by “stitching” them to a second layer of cloth. It’s a variant of doubleweave, but instead of the two layers of cloth (or blocks in the cloth) changing sides (see my 4 shaft sample here, and 8 shaft scarf here), there is a definite “front” and the two layers are just attached in spots.

I couldn’t make head or tail of the theory, so decided just to give it a go.

Here’s front and back of sample 1. The front layer uses a fancy textured yarn (slubs, glitter, loopy bits, you name it) for warp and weft in a 2/2 twill. It’s set at 4 ends per inch, which would collapse into a nasty tangle left on its own.

The back layer is a fine cotton (no idea of the formal spec – it was on sale at a knitting machine group get-together). It’s in plain weave, 20 ends per inch.

I’ve laid out the draft to try to make the concept behind it clearer. The thin cotton weaves plain weave on shafts 5, 6, 7, 8 – over on the right of the tieup. The fancy yarn weaves twill on top. Where a fancy weft is hidden between two fancy warps floats, a cotton warp is raised to trap it. You can see it in the draft – when 1,2 are lifted for the twill, up comes shaft 7. It’s pretty much invisible from the front, but it’s “enough” to attach the two layers together.

The trouble with this sample is that it isn’t really enough. There aren’t enough attachment points to keep everything firm. It would be nice to have a link on every weft – but either they would not be hidden between two warp floats, or I would need extra shafts (I was working on the 8 shaft Ashford loom).

Sample 2 solved the problem (well, Liz gave us the solution!).

Instead of attaching the layers by raising cotton warps, attach by lowering (ie not raising) fancy yarn warps. The fancy yarns are already on separate shafts for the twill, so I can move them independently (in each repeat of the twill) without needing extra shafts. The sample’s set was slightly different – I actually had only 4 cotton for each fancy on this one (I forgot when recreating the draft), with 20epi for cotton and 5 epi for fancy. I haven’t wet finished this one yet, but it definitely feels much more stable, although still a bit too loose for most uses. The fancy yarn is plied very loosely and could do with even more stitching points.

Sample 3 is exactly the same structure and epi as sample 2. The only difference is the fancy yarn used. This is also a thick and thin slubby affair, but overall thicker and more tightly plied. It is holding together very nicely. The back layer is a bit puckered (also not wet finished), but it’s quite¬† attractive.

Sample 4 is based on a photo in Doubleweave on 4 to 8 shafts by Ursina Arn-Grischott. This is the same warp, weft and set as sample 2, with a change in threading. Top and bottom layers are both plain weave. As well as stitching points there is an actual exchange of blocks as in normal double weave. The sample is structurally stable, but I think there is too much show-through in the cotton layer, so you don’t get a good impact from the exchanged blocks.

On sample 5 I used doubled cotton threads in warp and weft – a purple and a red held together. Everything else is as in sample 4. The thicker “back” cloth has much more visual punch. I really like this one. It’s very stable, the simple cotton squares and lines provide a good contrast and foil to the fancy yarn. I like both sides (backed fabrics are generally one “public” side). The only question is how to use it – possibly a cushion cover?? It’s not drapey enough for a scarf. BTW I don’t have a proper draft for this. The book didn’t give details (and the photo fabric was different and I don’t think could ever be done on “4 to 8 shafts”! – it had at least 3 blocks of double weave). I constructed this from the photo, input from Liz, some scrawls on a spreadsheet, then some trial and error on the loom).

This is just a scratch on the surface of backed fabrics. I’ll have to come back to it one day, but class has already moved on to the next topic…

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February 2010

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