11/11/2016
Time to share a few sewing tips. Please share with your sewing friends.
HOW TO:
Sew A BOX CUSHION
A so called box cushion is commonly found on sofas, boats and window seats etc. Boxy by nature as opposed to a scatter cushion, which is a joining of two squares or rectangles with or without piping between them and a zip to the bottom edge or an overlapping back of some design for cushion filling.
A Box cushion has a border sewn between the two panels, all round three sides, and a zip border (sewn between 2 narrower fabric strips) made-up to go along the 4th side or back/bottom of the cushion. Collectively the basic parts are two panels cut to a shape, the zip border and the long border or sidewall that goes round 3 sides.
Whatever shape the panels, the principles for sewing are exactly the same. This is my way of doing a simple square box cushion in plain fabric (no stripe matching) and no piping.
Take what is useful and adapt it. Ask for clarification if I am in any way unclear.
Making a square box cushion as pictured, unpiped and with a zip across the back, is the easy starting point. We will cover piping and pattern matching if you want, at a later date.
So two panels, same size, cut carefully, mirror images of each other. You might mark the back/inside surface with chalk so when you rummage through the pile of bits on the table beside your sewing machine you are definitely sewing the front at the front and your fabric face-side out.
The long border (or side wall) needs to be 1" wider than the finished thickness of the cushion cover required and long enough to reach from the back corner down the side across the front and up the other side plus a bit for luck. Join extensions on if necessary (so that they will be hidden at the side).
The cover should be eg 4" sewn for a 4.5" cushion interior. This slight tightness helps create 'a good fill'.
The plan size of the panels needs to be cut 1" wider and longer than your cushion's finished size.
There's a lot to getting this measuring v cutting job just right and keeping it simple initially will show up any fundamental errors you might make now, before you hit the big time.
Think twice, cut once.
For ease of handling and learning we will set our finished cushion size to 15 inches square with a 4" border.
Cut the main panels 16" square the sidewall (3x15 plus a bit for luck) 50" by 5" (to finish at 4") and zip borders (see below for more detail) at 16" long.
When tackling an actual project measure the chair/sofa/window seat (frame) size you need to fill, never copy an old cover exactly. Use it for guidance.
You will faithfully copy stretch or shrinkage if you simply trace round the original parts of a dissembled cushion cover.
Use an original cushion panel for shape detail and for angles and curves by all means but refer back to your measurements of the actual frame or window seat. Cut to the job - not to an old cover's sizes.
ZIP BORDER
The zip border has three constituent parts and will be the same length as the back of the cushion panel and the same width as the sidewall when you've finished making it up.
Making up the zip:
Two strips of fabric will have zip sewn between them. Half inch seam allowances both at the zip and at the panel's eventual sewing edge are needed.
Cutting a zip border:
Sticking with the example size of a 4" finished sewn border works out as follows. Half of 4" is 2". Then add half an inch at the zip and the half inch needed to sew onto the main cushion panel. You'd cut strips of fabric (I call them zip pieces) at 3". Cut them at 3.5 inches by all means and trim down after sewing until you trust your technique.
Cut the zip pieces the same length as the cut size of your cushion panel's back edge (16")
In our simple starter box cushion we will finish the zip at the back corners of the cover. Zips do commonly go round the corners and down the sides a few inches just to make cushion filling less dangerous for the zip. 99 times out of 100 I go round the corner. I also hide the closed zip runner under a folded pocket made by folding the sidewall over on itself. But that's another lesson.
A zip that does not go round the corners remains unseen if the seat cushion sides are seen when the cushion is in use.
Using a zipping foot or any foot that allows the needle to sew close to the zip's teeth, fold over a half inch of the fabric and marry it up with the zip ; with the zip teeth facing upwards, the zip itself lowest, under the folded edge of your fabric, sew down through the lot. Keep the half inch fold and the fold's edge's closeness to the zip teeth consistent as you go. Take your time. Don't sew your fingers to the zip. Getting attached to your work is credit-worthy in any other profession, not sewing.
A little front-to-back tension on the zip as you sew (NOT the fabric on top of it) will stop the zip gathering and curling when laid flat on the table after sewing. If it curls (looks like a road running over small round hills) undo and try again until you get this tension game right.
Repeat on the other side of the zip with your second fabric strip. Ensure you maintain that flat zip tension and that both fabric pieces start and finish level at both ends of the zip.
As you sew the second fabric strip to the zip compare the ends nearest you. Adjust zip tension to make the ends match up. Check how flat your zip looks once sewn. It's worth persevering and getting this technique right. Once you've got the idea you know what to look for early to keep the zip neat. Minor un-flatness will be stretched out by the cushion interior. Check whether you'll get away with it by gently testing whether any hills flatten easily. Big tug? Sew it again.
A word on zips. Continuous zip is very flexible and can be applied to any size job. 'Set-length' cardigan zips or closed ended zips are good if too long and can be trimmed to the length of your fabric zip pieces.
Beware metal zip teeth. You will soon be sewing over the zip teeth and they eat needles and scissors. Plastic zip teeth are better and also corrode/oxidise less long term. Continuous zip comes in different gauges. No3 has 3mm zip teeth good for smaller cushions but vulnerable to breaking when filling larger cushion covers. No5 is my go-to gauge for robust, needle friendly use. My needles are 19 gauge (thick industrial things). Domestic machine needles are thinner so hand-drive your machine over zip teeth and if the needle hits an impasse ease it on its way through the zip by moving the zip slightly sideways under the needle point.
Continuous zip can be ordered by the mtr online or I can supply bits and bobs. Don't forget the zip slides (or runners) to go with the zip. Beige, white and black are stock colours.
Putting the zip slides onto continuous zip can be entertaining in a grrrr sort of way. The trick is to cut close to each side of the zip teeth about an inch in from the starting end. Fold the fabric flaps out of the way and snip off the exposed plastic zip teeth level with the end of your two cuts. Open the zip teeth just enough to feed on the zip slide. Grab the flaps, wiggle the slide and it will find its way onto the run of teeth re-closing the zip as it moves away from your entry cuts. If sewing several covers put several zip slides on at once and slide them down the chain out of the way. Leave one behind for the first cushion. Don't go too far with the others, reversing will open the zip and you might as well chop off that section - its no fun sewing separated zipping.
So the zip border is complete. Flat, still a good length compared to back edge of cushion panel, zip sewn between two strips of fabric.
Now check the finished width of the fabric-zip-fabric border matches the width of your long border/side wall. Trim as necessary. In the photos my trim corresponds to the width of the zip teeth. Normally I'd adjust my seam allowance rather than trim so little off. If however your zip border is narrower, you might have folded a big half-inch alongside the zip teeth. Easy done, no harm, just frustrating; undo and re-sew. Cutting the fabric strips that bit more than 3" is a safe bet but you'll be doing a lot of trimming down afterwards.
Next step. Putting the cushion together:
Sew the sidewall to one end of your zip border, sewing over the zip teeth. Doesn't matter which end of the zip. Sew back over the teeth a few times if needle-safe to do so. This strengthens a weak spot when it comes to filling the cushion.
So you now have two cushion panels, a long strip of sidewall fabric with a zip border sewn at one end.
Place the zip border face up on the machine the sidewall in your lap. Place the back edge of one panel, either will do (the 1st panel) edge to edge on top of the zip border covering up the zip border. If you marked the back inside surface of your panel fabric you should see the mark uppermost now. Now slide the lot away from you under the needle (not sewing- just positioning) to get the next (2nd) back corner under the needle with the sewn join of the zip border to the sidewall under this nearer back corner of the main panel. Match up the panel corner and the border join and sew round the corner.
You could have a look now and see if your aim was good by turning the corner out. The panel corner and the sewing joining zip and sidewall should be matched. No zip coming round the side; no border sneaking round the back. I snip the border fabric towards the needle while it's through the corner point to allow the fabric to 'go round the corner' you'll spot the idea in the photos.
Now, keep sewing round all three sides of the panel (back to corner 1, as yet still vacant). Trim the long border as necessary to finish level with the back edge of your cushion panel. The zip border is still loose. Bring zip border and sidewall loose ends together and join up.
Again with border beneath panel sew round the corner and along this final back edge to complete this section of the job.
All 4 panel sides are sewn to the sidewall (side front side) and the zip border (back edge).
Beware of excessive gathering of any lowermost layer of fabric sewn on the machine. The teeth act aggressively if allowed to but this can be countered by stretching the lower fabric layer SLIGHTLY. Just enough to stop those teeth having free reign. Walking Foot machines are less prone to this, designed to be in fact.
Experiment with two pieces of spare fabric. Mark both in exactly the same places along their length, sew them starting level, see what happens on your machine. No gathering (the marks remain matched) this is good. If the underneath fabric shifts apply a little tension to it. Not the top layer. If you hold the top layer and allow the lower to be free it'll gather a lot. This can be useful in certain applications but not when we are sewing this box cushion.
The borders were sewn to the first panel with border underneath. Any slight gathering effect caused by the action of the machines teeth will not have affected the panel size. This is important and why we did it.
For this gathering reason never sew the second panel to the nearly complete cushion starting at one corner and sewing all the way round.
Mark the sidewall opposite each sewn up corner following the weave across or using the square edge of some paper. 90 degrees critical. Don't guess it.
I nick the fabric but you can use a pin or chalk.
Nearly done:
With main panel on top of border match up each panel corner over your nick or chalk mark or sewing join, and sew a couple of inches ONLY round each corner. Match and join all 4 corners this way leaving the sides unsewn.
Finally sew along the sides and back 'joining up the dots' (the sewn corners).
For longer runs such as window seats, mark the panel half way or at regular intervals and repeat the same intervals and marks on the opposite, as yet, unsewn side of the sidewall. Join up the marks leaving unsewn gaps. Join up the dots afterwards for perfect fit all round.
Sewing a long run in one go invites a problem at the far end. Join up the dots, as many as you like. I mark panels in many places as I cut. Having cut the first panel, I flip it over, copy/cut the mirror image so I know it is the same size and as I go round cutting I copy the nicks or mark in several places (round curves or along longer runs) between obvious corners.
Once one panel has its border sewn all round I pick and chose which marks I transfer across the border (at 90 degrees) and marry up the 2nd panel mark by mark, sew a couple of inches at each and move to the next - all the way round leaving gaps- then join up the dots. If I've joined up two wrong nicks it's easy to undo the short sewn link.
Your cover is sewn but you can't get in!
Reach through the fabric to pinch at the zip slide if your zip is fully closed. Or poke the zip with a pokey tool behind the slide. Undo the zip enough to to get your hand in to open up properly. Turn your cover right way out. Da-nah!!
Hopefully!!
Cheers
Neil
