These add-ons to "power looms" were invented by Joseph Marie Jacquard in the early 1800's and revolutionized weaving. It was suddenly possible to weave very intricate patterns much more quickly. Patterns were fed into the loom using a set of cards with holes - effectively punch cards. For this reason, the jacquard loom is considered a forerunner of modern computing! The systems were expensive to purchase and operate, requiring highly-skilled weavers and a lot of maintenance. But they could produce high-end damask cloth for table linens in large quantities.
Thanks to the "real" loom weaving lessons I've been taking recently, I was able to understand most of the working parts of these big devices. The patterning comes from having some threads drawn over the others for longer stretches - "overshot" - while the threads underneath continue the standard twill patterning. So the loom has two parts: the basic 4 to 8 shafts for the background twill weave, and the complex, punch-card-driven, individually-controlled string heddles behind this.
The looms were very large - with a second-storey superstructure to accomodate the punch card system:
[jacquard loom in full glory]
The operators basically stood at the loom with their bums resting on a slanted plank, so their feet could operate the levers for the shafts. In the picture above, you can see a leather apron draping down over the finished weaving (to protect it) on the lower right of the loom; the slanted wooden bum rest right in front of this. The white rope is attached to the jacquard pedal, which activates the card reader when the weaver steps on it. The holes in the cards determine which threads get lifted to make the weaving pattern, and each individual card represents one row of weaving. You can see other pedals below the loom under the weaving; these control the "background" weave.
[close up of the heddles]
In the photo above, the hundreds (thousands!) of string "heddles" hanging down with weights are the pattern heddles. Each can lift one warp thread, which runs through a small eye or loop tied in it. To the right you can see wooden frames holding more heddles; these control the background (twill) weave. There are 6 frames and each frame raises every 6th thread across the whole width of the weaving, in turn. These frames are controlled by the pedals, so that by pressing combinations of pedals, you can raise a predictable and repeating pattern of warp threads.
As you can imagine, setting up such a loom with thousands of threads is painstaking work that takes days. And if you make a mistake in threading the heddles, you'll see it in the pattern! So most looms were threaded only once, and then when the weaving was done it would be cut off carefully, leaving the heddles threaded with the remaining threads. You'd tie new threads to the remaining ones (which would still be threaded!), wind up, and start the new weaving.
You can see how fine the linen warp threads are in the following pictures. The wooden bar across the top photo is a so-called "temple"; an adjustable cross-brace with little grippy teeth at either end, used to stretch the weaving out to a specific width.
[very fine linen warp and the temple in action]
[damask in progress]
These table linens were made using a linen warp (the threads that run through the loom and the heddles) and a cotton weft (the threads doing the actual back-and-forth weaving). The complex pattern is best visible when seen at an angle; it's subtle. That's the beauty - very understated luxury!
The factory had the ability to make new punch cards, so that new designs could be made.
[punch card machine]
Once you have seen these looms, it's much easier to understand the modern ones that were in action at the museum's Textile Lab. This is where textile artists were at work, using computer-controlled looms to create strange new textiles and patterns. That's for next time!
This is definitely a place worth visiting, if you are a spinner or a weaver. It's located in an old wool-blanket factory, so there are some rooms dedicated to the old machinery (still all in working order!) that was used to make blankets.
There are other rooms dedicated to the history of jacquard weaving (I'll be blogging about that in a later post), but the major attraction is the Textile Lab, where modern, computer-driven weaving and knitting machines are used by artists to push the boundaries of current tech. Again, for a future post!
So, let's get started. Quickie tour of the blanket factory:
The factory was in operation between 1900 and 1940, and produced 100% woolen blankets from bales of local wool. The blankets were woven and fulled on site and the entire production chain can be viewed.
The process starts with the "picker" (well, OK, it's called something else in Dutch). The wool shown in the pictures is pretty fantastically clean, and I'm not sure if this was actually the case when this puppy was in current use...but we'll not get picky about this.
[first stop: the picker]
Then, a couple of "carding" steps followed, to produce thin webs of fleece and finally narrow ropes of fleece. Unlike other mills I've visited, this factory didn't use a pindrafter.
[carding, step 1]
[thin fleece mat moving onto second carding step]
[second carding step, producing thin ropes of roving]
The thin rovings that come off the second carder look a lot like those wheels you get from Briggs and Little, called "country roving" - the ones you use to make Cowichan sweaters. See photo below:
[what comes off of the second carder]
These wheels were then used on the "spinner", which was a sort of automated drop-spindle. It thinned and twisted the roving into single-ply yarn.
Then, weaving ensued. This step wasn't explained fully in the setup (all that was shown was how they set up a warp chain with a machine to do sectional warping - and they didn't demo it with the yarn shown above), but I understood that they produced double-woven pieces of woolen cloth (twill weave) that were then fulled and finally run through the teasel machine. The blankets were of a solid colour, with one side a lighter shade than the other.
The "fuller" took the blankets, soaked in a hot solution of ammonia and soda, and forced them through a pair of rollers, first in one direction and then 90 degrees opposed, to felt the wool fibers. Several passes were required.
After fulling, the edges were hemmed and the blanket was run through the "teaseler" a few times: basically a bunch of rollers with nasty burrs on them to raise a nice fluffy pile on the blanket.
[closeup of the nasty rollers]
Lots of factors contributed to the downward spiral and eventual death of the factories: the rising popularity of the down-filled or synthetic duvet, the fact that we have central heating in all our houses now, and the rising cost of land which makes selling the factory itself more lucrative than running it as a business.
Wool blankets are a rarity these days. Most folks have one only as a sort of decorative throw, to cuddle under when watching TV on a winter night, or by a summer campfire. Blanket factories were once relatively common in northern Europe, England, and even in on the east coast of the US.
1. KnitPicks Hawthorne - I used the "tonal handpaint" colourway. I was hoping that this yarn would be a "budget" version of Woolen Rabbit Pearl, and it some ways, it is that. At half the price, it certainly is "budget".... The yarn base is nice - not merino, so not as soft as Stroll - with a nice tight ply and lots of boing, so I find it pleasant to knit with. The dye job is not as nice as Woolen Rabbit - the colourways are not as subtle and it stripes in short sections. I think that it's probably not suitable for complex texture designs (like cables) because the colours are overpowering. I've seen other reviewers complain about excessive colour bleeding, but I have not had any issues. I will have to see how this yarn holds up in the long run.
2. Drops Fabel - this is a very popular European sock yarn that I have now finally found a local-ish source for. The colour selection is huge. It's superwash wool (not merino) at 410m/100g, and feels pretty close to Regia, although a little harsher and a bit splittier to knit with. It has an excellent price point! Again, will have to see how this holds up through the laundry.
3. H&W Comfort-Wolle sock wool (uni colours) - got this online from a retailer in Ontario; it's not a common yarn. But, very very nice, right up there with Regia. I'm pumped to see how this will handle repeated laundering; if it's good it will be a close contender to Regia!
4. Not sure if this qualifies as a sock yarn, but I've been knitting a project with KnitPicks Stroll Gradient. Yeah....no. Not something I'd knit socks with - the gradient isn't really a gradient - the colour changes are too abrupt. Also, some of the colours stripe/pool during parts of the "gradient". And then there's the fact that it's Stroll - a yarn I am starting to like less and less...
I have recently found an amazing online source for sock yarn: Wool Warehouse. This outfit is based in the UK but shipping to my front door is a flat-rate $CD7, which is f*&*ing cheap, folks! Not to mention that the yarn price is amazingly low! I looooove their selection of Y-chromosome friendly Euro sock yarns.
So, a few days ago, this showed up on my doorstep:
[a crapton of sock yarn, in a lovely organza bag!]
Love the yarn. Love the bag! Can't wait to get started!
I recently knit up a pair of socks for my 20-something son, who is rather conservative in dress, and discovered that the pattern I had chosen (a simple knit-and-purl affair) was just as nice on the flip side of the work. Ta-da! Reversible socks! I knit them toe-up, with flap-style heels, and as long as you are neat about the ends, there is no reason why one cannot wear socks inside out. Right? Ask my son. He does it inadvertently all the time. Apparently one can wear socks twice as long this way before washing them. Yeah, mom!!!
Here's the result:
[socks, "purl side" out]
[socks, "stockinette side" out]
The stitch pattern is a [K3 P1] rib, that gets offset every 6 rows (or something like that - can't remember exactly, but it doesn't really matter!). So the socks are stretchy.
Another knit-and-purl pattern that's reversible is "wavy rib" ( [K4 P2] for 4 rows, then offset it). I knit up these for my husband and used the toe-up Fleegle Heel. I like this one better for wearing inside-out; it doesn't have ridges along the sides of the "flap".
[wavy rib socks, "right" side out]
[wavy rib on the inside = mini basketweave!]
I figure there must be many more reversible patterns out there, lurking in the knit-and-purl section of your local stitch dictionary...
So after a few fingerless mitts done with twined knitting, I have now tried a pair of full mittens.
I did these 2-at-a-time, in an effort to reduce the differences between the two mittens. It turns out that:
1. 2AAT is easy on single-colour twined knitting! You can use Magic Loop or 2 circs, and you just use 2 centerpull balls and use the yarn management technique described in volume 1 of twined knitting. It's just like socks!
[twined mitts, 2AAT, in progress...]
2. If, like I did, you want to use more than a single colour in parts of the mittens (like, say, in the cuff part), I'd recommend that you estimate how much of each colour you're going to use and wind a centerpull ball starting with one colour. Then, when you've wound up enough of that colour (example: 10 g blue for the cuff), tie on the other colour and continue winding your centerpull ball with the second colour. The result is a centerpull ball with the outside end in one colour and the inside end in the other. Ideal for bi-colour twined knitting!
[bi-colour centerpull balls, inside portion is blue and outside, white]
3. Seems like a lot of twined colourwork is 1x1 - either vertical stripes, checkerboard, braid, or variants thereof. So in each row you use 2 colours alternately, 1 stitch each. If, like me, you want to intersperse these motifs with rows single-colour knitting, you have two options:
use one of the strands and do a few rows of plain stockinette (not twined knitting), or
tie on a second strand of the single colour and continue in true twined knitting.
Having tried both of these methods, I recommend the first - having to manage three strands, two of which are twining and one just "resting", on 2 mittens simultaneously, is a royal pain in the ass. Besides, nobody is going to see that those 2 rows are not twined.
And - perhaps obviously - if you want to execute a design that has floats longer than 1 stitch (zigzags, 2x2 checkerboard), you can still "twine" the two colours on the back over longer intervals. Or, just revert to standard stranded (ie. not twisting the floats) knitting over those portions of the design. Nobody is going to notice the difference, as the emphasis will be on the colourwork, not the structure of the knitting.
Here are some design tips:
I've learned from experience that when you do twined purl, with the yarn twisting in the front of the work, it overhangs the row below it and makes it disappear. So, in the mittens above, I knit two rows of single colour stockinette before doing each braid or ridge motif and one row after it. This makes the braid or ridge look like it is centered on a stockinette background.
One of the fun bits of twined knitting is the "crook" stiches, which are essentially a trio: purl -knit -purl, with the float of the first purl stitch held in front of the knit stitch before being used in the second purl again. In my opinion (having tried both now), monocolour crook stitch patterning (used in the white portion of the mitts above) looks best in a light yarn, rather than in a dark one. White or light grey really makes the texture pop out more - I think because you can see the shadows. You can adapt regular stranded motifs (like scandinavian stars, or zigzag lines) to crook stitches, but the crook stitches require a minimum of 3 stitches to make, so the designs will be wider and "coarser".
You can use single crook stitches (trios) to make "bubbles", or rows of them to make a nice sort of chain (see photo below). Crook stitches done over a striped background are really effective too!
[Latvian braid on bottom, some purple/white colourwork,
single twined purl rows in purple outlining 2 rows of white crook stitches,
crook stitches on striped background,]
I really love the effects one can get by having both twisted floats on the front of the work. "Latvian Braid" is basically twined purling, with two colours of yarn and the floats in the front of the work. These things are fun to play with, but I've found that you get a horrible jog at the beginning-of-round with them. I've not yet figured out how to solve that problem. In my mittens, I've disguised the jog by the simple expedient of sewing a cord over it - my son wanted the two mittens joined by a long decorative cord so he can keep the mittens hanging in the arms of his coat.
I'm much happier with the amount of blending now. Also, the original roving was space-dyed (ie. stripey), with two main colours: pink and gold - which I converted to a gradient thusly:
1. rip the roving into chunks so that each chunk was as much a single colour as possible, and then
2. run the strips through the drum carder to fluff them out; then,
3. follow the instructions in this video (it's in German, but I think you can get the gist pretty easily - turn off the voice and watch what she does, it's not hard to get) to create a gradient.
To spin from the batt, I did this. It's lovely fluffy stuff and drafts pretty easily, although I'm finding a few neps. The single is hairy rather than smooth (that's what you get with a longwool, in my experience) and as I'm spinning I'm hearing the wool tell me it wants to be a shawl rather than socks. We will see what comes of this!
I'm going to have to explore the drum carder more. I love how it can make gradients, and how I can make custom blends!
My friend Mary is in her 80's and an accomplished knitter. I spotted her wearing this beautiful Aran cardi a while back, and I requested the pattern...but it turns out the sweater is as old as I am and the pattern is long gone.
So, instead, she lent me the sweater for some analysis. I invite you to share on my "sweater deconstruction" journey...
Here's the sweater. Lovely, no?
[vintage aran cardigan]
Just looking at it, you can see that:
1. it's been knit flat in pieces, and sewn together.
2. the sleeves are "set-in", not drop-shoulder or raglan
3. the font band is vertical (not picked up later and knit on), and has been knit separately and sewn on. Ditto the collar.
I think this method of construction was par for the course in the 1960's - nowadays lots of people tend to knit sweaters in the round, and do drop-sleeves, and knit on the front band and collar.
Let's have a look at the stitch patterns to see if I can figure this puppy out. I'll start with the easiest one; the one that the sleeves are knitted out of and that runs up the sides of the sweater fronts and back:
This is pretty clearly:
R1: knit on RS
R2: purl on WS
R3, 4: K1 P1 ribbing
Then repeat, but offset the ribbing.
Right? OK. Look really really closely at the ribbing.
[zoomyzoom on the ribbing part of the background]
The two blue arrows point to a column of sts from the ribbing rows, and the orange arrows point to the stockinette rows. You can see that the ribbing rows are twisted stitches while the stockinette is not. The left leg of each twisted stitch overlaps the right leg, whereas in the not-twisted stitches, the two legs originate from the same point. So, the actual background pattern is:
2 rows stockinette (K one row, P back)
2 rows twisted ribbing (KTBL, PTBL)
and then repeated, offset.
And don't feel bad if you got this wrong. I did, and tried plain ole' ribbing. Here's what I got, and you can see it doesn't look as nice!
I was trying to get that crisp, ripply look and figured at first it was my needle size, so I kept downsizing. But you can see it didn't help! My wool is different too, of course - it's woolier than Mary's, so that doesn't help with the stitch definition - but I'm glad I decided on a closer inspection. I will have to redo the swatch now!
Next up: the bobble cabley thing:
[bobble-cable, in context]
This one's a bit harder, but it's clearly 2 rope cables twisting in opposite directions, separated by a bobble. Duh.
Now, in detail - I had to look on the inside, and stretch the knitting out to count stitches - the cables are over 5 stitches, and every twist is made of up 3 stitches in the front crossing over 2 in the back, and this is done every 4 rows. They're asymmetric, which is kinda unusual.
Now, also notice that the right-side cable looks narrower than the left-side cable; this is particularly noticeable in the photo above. Why??
Again, let's zoom:
[zoom of bobble cables]
The stitches are again twisted! Telltale ridges are appearing along the RH cable (see yellow line to guide the eye). And, because the "through the back loop" technique twist stitches in the clockwise direction, I can imagine that a clockwise cable will look tighter than a counterclockwise one. Which is what you see in the pic above, right?
So, I have embarked on a swatch to combat this problem. It involves knitting TBL on one side of the bobble, and reseating the sts prior to knitting them, on the other side. It matters not which side you do what on; the point is that the stitch-level twist and the cable-level twist on each side are symmetric (either opposing each other, or going the same way, on each side). Of course, you could also omit the whole twist thing and just knit and purl, but then your cables will not be as tightly defined.
To reseat a stitch, you slip it knitwise to the RH needle, then transfer it back to the left while keeping the twist in place. Remove your RH needle from the stitchcompletely, or you will have a strong desire to knit it through the back loop, which will undo what you've just done! Now the stitch is reseated and ready for regular through-the-front knitting or purling.
Now, as to that bobble, this took me several tries, as well as some dives into stitch dictionaries to find out how to do bobbles. In the end I settled on a 5-stitch bobble. You can see my swatch below. Both cables are the same width and the bobbles look the right size. And below that, you can see where I tried plain old untwisted sts on the cables. I don't like the result as much!
[my bobbley-cable swatch, with TBL and reseated sts]
[another swatch, this time with no twisted sts]
Isn't this fun? Oh, and here's the chart:
[chart for bobble cable]
OK, almost done. Let's look at the diamond things.
Yikes. This looks complicated. These are 4-stitch wide travelling bands defining a diamond, which is filled with moss stitch. The 4-wide bands are themselves cabled. To get this, you need to cable on both the front and the back of the work. If I use the bobble-cable on either side as a guide, I'm guessing the diamond takes 24 rows or so to complete. It stretches over 21 sts (includes 2 reverse stockinette "gutters" on either side).
Here's my chart:
[diamond pattern chart]
You'll see that I've done the travelling on the wrong side of the work (even rows) and the cabling on the right side (odd rows). I've worked up a swatch, too...
[diamond cable swatch]
I'm not entirely happy with this yet though. I think especially the diamond cable swatch is too small; too tight. I will try all these again with larger needles, now that I have figured out that the background stitch reqiures twisted sts!
I must say I am pleased that I am able to recognize a high-quality knitted garment. And close examination of it shows lots of expert-level pattern details! Mary is indeed a fine knitter.
OK, I finished those z-ply twined mittens. Half-mittens, actually.
Here they are:
I am very happy with them. The fabric is amazing: very dense, yet still soft and pliable. I love the surface decoration you get with this technique - it involves nothing more complicated than carrying the floats on the front of the work, rather than on the back (the floats are never more than 1 stitch long).
While the outside of the knitting doesn't look that different from regular stockinette, the inside is quite different:
[inside view of twined knitting]
All those twists create little ridges on the back of the work and make it thick and lofty. I'm sure this would make amazing slippers!
I find that my gauge is quite different with this technique: it's much tighter. So although the mitts were supposed to be husband-sized, they ended up being 2 sizes to small and therefore are now mine! So I've done another pair, using standard s-ply yarn (Palette from KnitPicks, which is fairly loosely plied fingering and a little finer than the Hygge Tveband), and I explored colourwork rather than texture. I upsized them and cast on 80 sts to make them bigger. Here's the result:
[two-colour twined mitts]
These were fun to make as well - I really like the combined effects of colourwork and texture. Using colours that are close together (grey and white) makes the mitts a little less eye-popping.
Since I used s-ply yarn, I twisted the two strands counterclockwise to unply the yarn as I knit. I see that I can't tell from the finished fabric that the initial yarn was s-ply rather than z-ply, and I didn't find the twisting action more difficult in one direction vs. the other...so why did the old-timers decide that z-ply yarn was preferable to s-ply for this technique???
I think it may have something to do with the yarn management. I found that while the yarn tangles with z-ply yarn, I could at least knit a few rounds of mitten before having to let the ball spin to get rid of the twist. Not so with s-ply yarn! After half a round, I had to spin the ball. Somehow the twist stays way up high, near my knitting hands, and gets nasty and tight really quickly.
My younger son is about to head off for a 4-month internship in Saskatoon, and has requested a pair of full mittens in order to be able to cope with the -25C weather. So I'm off to produce another set! This time, I will try two-at-a-time, to see if I can get that working.
OK, now that I've knit a little bit of twined knitting, I've already learned some stuff.
1. This is essentially a "throwing" technique. It's also butt-slow.
I am lucky in that I can knit using "picking" and "throwing" techniques (ie. "continental" and "english" style) with equal facility, so I've been able to try both on this technique. And I find it much easier throwing - and if you can support that RH needle, so much the better. I thought at first I could pretend I was doing colourwork, which I find easiest/fastest by continental-style "picking", but quickly found it impossible. It's because you have to constantly twist the 2 strands together in the same direction, and you basically need to drop one strand to accomplish this. Hence the use of my right hand (since I'm right-handed), and the requirement to support both needles while my right hand is busy twisting yarn. I can see why this is limited to small objects (unless you are using pit knitting or a knitting belt or something, with ultra-long DPNs).
2. Get clear in your head which way you need to be twisting those yarn strands.
Roll 2 strands of yarn together with your thumb and forefinger:
[roll two strands together -
moving thumb up in direction of arrow rolls them clockwise]
If the yarns look like the picture below when you've rolled them, you have z-twist yarn and you need to twist the strands together with the bottom strand moving up and over the top strand - like you did when rolling the yarns together in the photo above. If you translate this motion into holding a screwdriver with your right hand, you'll see it's a "righty-tighty" move.
[2 strands of yarn, unplying as they twist]
If, as is more likely, the strands look like the photo below, you have standard s-twist yarn and you need to twist by having the top strand move down and over the bottom one. Try unplying your strands by moving your thumb in the opposite direction, in the picture above. This is the "lefty-loosey" screwdriver motion, yes?
[2 strands of yarn, plying together harder as they twist]
Play with this. Pick up your knitting and twirl the 2 strands around each other first one way, then the other, and you'll soon see which way unplies them. For z-twist yarns and the "authentic look" of twined knitting, you'll want to ensure the yarns twist "righty-tighty" during both purling and knitting. For s-twist yarns you'll need to do "lefty-loosey" during both purling and knitting to get the unplying effect - and note, this means you won't be doing the twists the way that Knitty article tells you to do it!
As I mentioned in volume 1 of this series on twined knitting, the twist is a personal preference thing. A "compact" yarn produces a fabric with a different drape and loft, and the stitch definition will be slightly different than if you knit with an "open" yarn. Try a small sample using each twist direction to see which you prefer.
I found it useful to do this unplying test as I started knitting/purling, so I could get the twist going in the right direction...which brings up...
3. Yarn management becomes an issue within seconds.
Because of all the twisting, you get a tangled mess pretty quickly. Best tip (thank you Principles of Knitting!): use two ends of a center-pull ball, ** pull off a "wingspan" or generous double armslength of both strands of yarn, and then clamp the two ends to the ball using one of those bulldog grips (or a clothespin, or a short knitting needle stabbed in and out a few times to trap the strands) so they can't unwind more. When you've used up the wingspan of yarn, dangle the ball so it unspins, unclip the yarns, and repeat from **.
[clamp the yarns to the ball using a bulldog clip]
Don't be shy about unwinding that "wingspan" - I've found it helpful to have at least 1m or so of yarn "free" at all times. With z-twist yarn especially, I'm unplying it as I knit and it helps to have the extra yarn free to "regularize" the twist. I've found that knitting straight-up twined for a few rows really makes things twisty, and that throwing in the odd crook round really helps decrease the twisting.
I've seen several writeups about the technique of "twined knitting", also known by its Swedish term "tvåändsstickning" or by the equivalent Norwegian term "tvebandsstrikking". It has been written up in Knitty here (with a pattern, here), and there are several YouTube videos showing the various stitches (knit, purl, and so-called "crook" stitches).
Twined knitting is done with two strands of the same (often even same colour) yarn, and with every stitch you twist the two strands around each other. Unlike stranded (colour) knitting, the yarns are twisted constantly in the same direction, never untwisting. The backside of twined knitting looks quite different from fair-isle colourwork - it's much denser. Knitting with two strands allows you to play games with loops of yarn from the strand you're not using, which leads to some fun textures. Also, because it's double-thick, it's very warm (and windproof, if done at a tight gauge, as is traditional).
You are traditionally supposed to twist the yarns in the opposite direction to which they were plied, so this action slowly unplies or opens up the yarn. This apparently makes the end product trap more air. I think it probably also enhances felting. Traditionally, the technique employed so-called "z-twist" yarn (for spinners: spun clockwise and plied counterclockwise) and the twisting was done by lifting the strand from the second-to-last stitch knit over the last stitch knit (ie. twisting the two yarns clockwise) on the back.
Nowadays, this type of yarn is hard to find, and most yarns are "s-twist" (for spinners: spun counterclockwise and plied clockwise). But, I was at Vogue Knitting in early November, browsing the vendors, and I came upon The Yarn Guys booth, where I chanced upon an American-spun special z-twist yarn (Hygge Tveband Sport) especially meant for this type of knitting. So I bought a couple of skeins....hence this series of blog posts!
[on the Left: good old regular "s-twist" yarn. Note that the strands lean LEFT,
like the middle part of the letter "s".
on the Right: special-snowflake "z-twist" yarn. Strands lean RIGHT,
like the middle part of the letter "z".]
Z-twist yarn is hard to find. Hygge Tveband Sport is milled to spec for the Yarn Guys and it isn't cheap (count on $50 for a couple of skeins - enough for 2 pairs of mittens - shipping incl). Contact them directly and they'll send the stuff to you. I've only found one other called Mora, which is sold by Nancy Bush at Wooly West (I've never ordered from this site). Note that I'm not talking about the Malabrigo Mora yarn of the same name.
But, if you want to use "regular" yarn (s-twist), hey, no problemo! For the most authentic effect, you just need to twist the strands counterclockwise on the back of your work: ie. bring the second-to-last stitch thread under the last stitch knit. This action then has the same effect : it gently unplies your yarn.
I'm not making this up, this info is from that eminent bible : Principles of Knitting by June Hemmons Hiatt, who lists her sources. But I do I note that the point of unplying your yarn is not discussed in the Knitty article, nor is it mentioned in any of the videos on YouTube that I skimmed. In fact if you use the traditional "clockwise" twisting actions meant for z-twist yarns and shown in the Knitty article, or demonstrated on YouTube, on readily-available s-twist yarn, you will compact your yarn rather than opening it up...this is a picky detail, obviously, but it matters to some kntting geeks (ie. me). Compacting your yarn will affect the stitch definition and the final drape/loft of your fabric. It's a personal preference thing, so try both twist directions to see which you prefer!
Another, even more subtle, point is that regular knitting - even without twining - tends to unply z-twist yarns, making them rather unpleasant to knit with (this is the reason millspun yarns are s-twist). So twined knitting with z-twist yarns delivers a double whammy of unplying. Again, this will matter only to knitting geeks. I'm really wondering why the good knitters from way back settled on z-ply yarns and clockwise twisting, rather than standard s-ply and counterclockwise twisting...will have to do some experiments...
I'm knitting up some twined mittens now. And I'll be posting on what I learn as I go.