Sewing and hemming knits Exhibit D

Before we move on from conventional sewing machine it is important to talk about twin-needles. The two parallel rows of straight stitches they make, combined with that crazy zig zag going on below, renders this mode of top-stitching very flexible and therefore perfect for knits.

My sample of my own twin-needle sewing comes from a top that was on my body just pre photo. You can see a twin-needle hem here at the bottom of a very comfy bamboo knit T shirt I made when I had only access to my ordinary machine and not my cover hem.

A couple of facts first about twin needles if you haven't used them much before before we get to the pictures:

• Any machine with a top or front loading bobbin can accommodate a twin needle. A side loading Singer Featherweight cannot for instance.
• Twin needles come in a wide variety of set apartedness and also have ballpoint/stretch versions. I have found it makes sense to have several on hand if you sew with different fabrics:
• closer twins work better with thinner and really stretchy fabrics, that's why I used one like that in the pink top below. I find that a wider twin, coupled with the activity of the zig zag can cause definite tunnelling (fabric forming a ridge between the stitches) in thinner fabrics.
• A wider twin works much better with heavier fabrics - they hold the stitches in place farther apart and the wider set parallel lines look more like RTW
• Again wooly nylon thread in the bobbin will give the stitches more bounce and also reduce tunnelling.
• If you are on a desert island or somewhere where only straight stitch machines are available, a narrowly set twin needle can be used to stitch a very effective, strong, stretch seam. Handy survivalist information to have.

So back to pictures of twin-needling, my soft pink top.

The fabric shows some wear at this stage, as favourite garments do, but the hem has held up well and shows how twin-needle hems do that. Also you will notice there is not much of the dreaded wave despite the fact that this is an extremely stretchy fabric:

Inside view

The thing to notice about the inside view here is the white thread you see poking out just a bit from behind the serging I did to the raw edge.

What I did here was use a fusible thread in the lower looper - you can get that now at most sewing stores - and use that fact to hold the hem down when I pressed it into place before stitching. 

At this point I think it would be useful to deviate a bit and talk about how to prepare a knit hem and keep it folded up while you stitch it down. Here are all the methods I have tried/use, I will try to remember to say what approach I used in the samples I will show you over the next few days.

Here are different ways to hold a hem in place:

• Let's start with the fusible thread. If you are serge finishing the raw edge this can be a great idea- just put it in the lower looper. Next press down lightly with a pressing cloth from the right side. Once pressed into place your hem will hold still while you sew without a lot of movement or without the hand of the fabric being changed substantially. This is particularly good for those turn over and top stitch instructions for necklines or armholes as the fusible eliminates that annoying rippling you can get when you stitch.
• Next of course is pinning. Nothing new here except be aware in bouncy fabrics that you might get a sort of ripple around the pin as of course you are only holding that particular area still not the whole edge of the hem. Pins work more reliably IMO in less stretchy knits. Pinning can also be problematic of course when cover hemming - you have a choice to either keep the pins on the inside which is crazy unless you are dexterous enough to pull them out from the underneath layer of fabric just before you hit them. Alternately you can pin from the top of the fabric, with the folded hem hidden when cover hemming, which has its own challenges due to the unseen raw edge. (Are you able to follow this? Who would have thought there would be so much to say on this topic?)
• Steam-a-seam and other named fusible heat sensitive webs/tapes. Fine with heavier knits but in my own experiments these webs can add a little stiffness to the hem which is an issue with the finer, stretchier knits.
• Double sided adhesive tape. Use just like the heat sensitive webs/tapes, stick it to the wrong side of the hem and fold it down and stick to the wrong side of the garment, except they are just sticky and don't need heat to work. This is exactly why I prefer this kind of tape to the heat sensitive tapes - the less pressing you can do to a knit I feel the less chance you will kill it flat or out of shape. The only real downside of these tapes is that the rolls are very tiny. If anyone has a source where I can buy this stuff in sensible sized rolls please let me know.
• Hand basting. Yes I know old school. I actually have started to hand baste down a fair number of my knit hems. Unlike pins it is possible to hold more of the raw edge down with hand basting and unlike the heat sensitive tapes once the basting thread has been removed there is of course no remaining impact to the fabric hand. When cover hemming in particular I find hand basting useful as I try to baste close to the cut edge. This is very helpful when stitching from the right side - I have a good idea where the raw edge is even if I can't see it.

So back to twin needles:

Pros:

• You can use your ordinary sewing machine and apart from having to roam around trying to find your twin needles you can stay where you are without having to fiddle with new threading etc. and sew a RTW look a like knit hem.
• The needles come in different widths so your range of parallel possibilities is also much wider than say with a cover hem
• Because you are working with a conventional machine and can back tack at the beginning and end of every line of stitching you are spared the sometimes elaborate strategies required to tie off a coverstitched hem.
• You can use the free arm of your sewing machine, not all cover hem machines have that.
• You can use more than just a straight stitch - sew a decorative or zig zag twin hem if you want - although I have never done that and probably never will want to.

Cons:

• Because you are working on a lock stitch machine you do not have cover hem features like a differential feed that can be activated to counter act wavy hems.
• Twin needles stitch down the hem but don't finish them. This means you have to either forget about raw edge finishing, you don't really need it in a knit anyway, or finish the edge before you stitch as I have done here.
• A twin needle hem is close to but not quite as professional RTW looking as a real cover hem. The raw edge doesn't have the same potential to be automatically covered up with underside loops as one sewn with a cover hem machine.

Grade: A