Onyx one-piece: Sewing Instructions

Step 0: Customizing and fitting your pattern

Decide what type of garment you’re going to make. This design supports several options:

• Unisuits (one-piece compression swimwear with sleeves and legs)
• One-piece pajamas (loose-fitting garment made with soft fabric, either short or long sleeved)
• Romper (casual garment with short sleeves and legs)
• Jumpsuit (casual garment with long sleeves and legs)
• Unitard (compression garment used for dance)

Decide if you want a hood, or to finish the neck with a neckband. If you want a hood, decide if you want a two-piece hood with a center seam, or a three-piece hood that also has a front piece, allowing for ears or other decorative feature to be inserted into the seam.

Decide if you want to add a simple gathered skirt around the waist.

Select a fabric (see fabrics for details)

Decide what lining to use, if any:

• Unisuits should use swim lining or a second layer of swim fabric for the body, to give form, to prevent chafing, and to prevent the suit from being see-through. The sleeves may be left unlined. If using multiple layers of lining, treat them as a single layer when constructing the garment.
• One-piece pajamas are usually not lined, except for the hood, which may or may not be lined with something soft.
• Rompers or jumpsuits may be lined, depending on preference, fabric, and purpose.

Select an appropriate sleeve length:

• 10-30% for short sleeves.
• 75% for 3/4 length sleeves.
• 100% for long sleeves (to the wrist).
• 115% is a good value if making a shirt with thumb holes (extends to the knuckles).

Select an appropriate leg length:

• 20-60% for shorts
• 90% for ankle-length legs
• 100% for legs that touch the floor.

Decide on a closure.

• One-piece pajamas usually use a coiled plastic zipper (#3-5 gauge).
• Unisuits usually use a half-length molded plastic zipper, #5 gauge.
• Unitards use a large neckhole and no zipper.
• Rompers and jumpsuits can use buttons, coiled plastic zippers, invisible zippers, or a large neckhole.
• NOTE: This design assumes the use of a zipper. If using buttons, you will need to add plackets and buttons yourself. They are not included in this design.

Decide whether to cut the front and/or back pieces on the fold:

• If using a zipper or buttons, do not cut the piece containing the zipper on the fold.
• For unitards, cut both the front and back on the fold (total of 2 pieces).
• For unisuits, cut the back on the fold if making a front-zip unisuit, or the front on the fold is making a back-zip unisuit (total of 3 pieces).
• For one-piece pajamas, rompers, and jumpsuits, cut only the back on the fold (total of 3 pieces).

Figure out what kind of fit you want and set your eases accordingly. Make sure you have an appropriate fabric. If in doubt, making the garment too loose is safer than too tight.

• For unisuits and unitards, you want negative ease. This will allow the stretch/swim fabric to form itself around the wearer’s body.
• For one-piece pajamas, you want positive ease and to smooth out the shape (ie., add extra ease to areas that cut in, like the waist, to give the overall garment a less fitted shape).
• Rompers and bodysuits use positive ease, with the amount and distribution of the ease varying greatly based on the intended shape of the garment.

The neckband length will be mostly determined by the material of the neckband. Stretch fabric will generally use a length of around 80%. Less stretchy fabric will be longer, but always shorter than 100%, and ribbed knit (traditional t-shirt neckbands) are around 60-70%.

Check around the hips, upper legs, and crotch fork, and make sure that everything is smooth and looks right. Small errors in measurements or options can cause issues here, and it’s best to tweak seat east, upper leg ease, crotch gusset width, and leg taper position until all curves are smooth. The outseam should roughly match the silhouette of the wearer.

Step 1: Forming the body

Note: If the front or back was cut on the fold, skip steps producing center seams. Note: These instructions are intended to form the seams such that the side seams extend backwards, and the center seams extend leftwards. Note: These instructions assume that the zipper is on the front. If the zipper is on the back or there is no zipper, the directions will have to be modified slightly. Note: If you’re having the zipper zip up across the neckband (recommended for unisuits), remember that when placing the zipper on the center seam.

If not using lining:

• (if front was not cut on the fold) With good sides together, place the zipper and neckband into position along the center seam, remembering to take seam allowance into account. Mark where the bottom stop of the zipper is, and serge/overlock the front pieces together starting at the crotch fork and stopping at the bottom stop of the zipper.
• (if back was not cut on the fold) With good sides together, sew the back pieces together.
• With good sides together, sew the front and the back assemblies together along the two side seams.
• Skip to step 2.

If using lining: Front (center) seam: (from the point of view of the wearer) Note: Seam will be formed on the right side of the assembly. Layer the pieces as follows, from top to bottom:

• wrong side up: fashion fabric, front-left piece.
• good side up: fashion fabric, front-right piece.
• wrong side up: lining, front-right piece.
• good side up: lining, front-left piece.
• Line up the four pieces and clip/pin.
• Place your neckband and zipper on the seam. Remember to take into account seam allowances, that the top stop of the zipper is at the top of the folded neckband, and mark where the bottom stop of the zipper is. Remove the zipper and neckband.
• Disengage the serger knife (it will cause issues near the zipper where a section would be cut but not sewn).
  • Alternatively, leave the serger knife engaged, but disengage it right when the knife reaches the point where your seam stops, and then continue without the knife until the stop point reaches the needles.
• Make sure the layers of fabric are lined up very evenly. Without the knife, you must make sure that every layer gets under the needles of the serger, or there will be holes in the seam of your garment or the lining.
• Serge/overlock through all 4 layers, stopping at the point you marked where the bottom stop of the zipper is.
• Flip the top and bottom layers (the front-left pieces) of fabric over.
• Re-engage the serger knife.

Left (side) seam: Note: Seam will be formed on the right side of the assembly. Layer the pieces as follows, from top to bottom:

• wrong side up: fashion fabric, back-left piece.
• good side up: lining+fashion fabric from prior steps.
• good side up: lining, back-left piece.
• Line up the four pieces, and serge/overlock through all 4 layers.
• Flip the top and bottom pieces (the back-left pieces) of fabric over.

Right (side) seam: Layer the pieces as follows, from top to bottom: Note: Seam will be formed on the left side of the assembly.

• wrong side up: fashion fabric, back-right piece.
• good side up: lining+fashion fabric from prior steps.
• good side up: lining, back-right piece.
• Line up the four pieces, and serge/overlock through all 4 layers.
• Flip the top and bottom layers (the back-right pieces) of fabric over.

Back (center) seam: Layer the pieces as follows, from top to bottom: Note: Seam will be formed on the left side of the assembly. Note: This is the last seam to complete the body, and the steps are slightly different in order to still have the seam encased between the fashion fabric and the lining once it’s finished.

• wrong side up: fashion fabric, back-right piece pulled over the main part.
• good side up: lining+fashion fabric, main part; from prior steps.
• good side up: lining, back-right piece pulled under the main part.
• Line up the four pieces, and serge/overlock through all 4 layers.
• Pull the lining right-side-out, so that the main bulk that was locked between the newly sewn parts is freed and the garment is right-side-out.

Step 2: Attaching the gusset

If not using lining:

• Place the garment inside-out and flat on your table, with the front of the garment face-up.
• With good sides together, serge or overlock the crotch gusset up the front of one leg, around the crotch fork, and down the other leg. Be careful to keep the layers of fabric together and aligned when going around the fork.
• Turn the garment over.
• With good sides together, serge or overlock the crotch gusset up the back of one leg, around the crotch, and down the other leg.
• Skip to step 3.

If using lining: Front Inseam:

• Place the garment right-side-out and flat on your table, with the front of the garment face-up.
• Push the back crotch and legs out of the way, so you have easy access to only the front crotch and legs.
• Place the fashion fabric gusset piece on top of the garment and running along the inseam, around the crotch, and back down the other inseam, with the wrong side up.
• Slide the lining gusset piece under the garment with the good side up.
• (optional) Baste the seam, taking care to secure the portion near the crotch, as it has a tendancy to slip and cause a hole in the next step if not well secured.
• Serge/overlock through all 4 layers to form the front inseam.

Back Inseam: Note: It’s not possible to hide this seam in between the lining and the fashion fabric, so it’ll be on the inside. For adaptive/sensory-friendly clothing, place this seam on the outside instead.

• Turn the garment inside-out.
• Flip the garment so that the back is facing you.
• Line up the gusset (that you attached to the front in the previous step) with the back inseam and clip it together.
• (optional) Baste the seam, taking care to secure the portion near the crotch, as it has a tendancy to slip and cause a hole in the next step if not well secured.
• Serge/overlock through all 4 layers to form the back inseam.

Step 3: Attaching the sleeves

• Fold each sleeve and, with good sides together, sew the sleeve seam from the hem to the armpit.

• Turn the garment right-side-out.

• Turn the sleeves right-side-out.

• With good sides together, clip each sleeve to the body. The longer side of each sleeve should be clipped to the back, the shorter side to the front, and the sleeve seam should line up with the outseam. Verify that the sleeve is properly attached. Serge or overlock through all 3 layers.

• Repeat with the other sleeve.

Step 4a: Attaching the neckband

• Fold the neckband in half short ways (so it’s half as wide) with wrong sides together, and clip it at each end and at the midpoint.
• With good sides together, clip the middle of the neckband to the middle of the piece without the slit for the zipper (the back piece if using a front zipper).
• Clip each end of the neckband to the corresponding side of the zipper slit.
• Place clips along the length, stretching the neckband evenly along the length of the neck hole.
• Baste the neckband to the neck hole, taking care to secure the two ends.
• Serge/overlock through all layers.
• Turn the neckband over. It should lay flat.

Step 4b: Constructing and attaching the hood

Assembling the hood:

• Place the two main hood pieces together with good sides together, and serge/overlock along the center seam (the curved seam running from the back of the neck to the top of the head).
• If using a front piece, place it against the back pieces with good sides together, and serge/overlock along the side seam (the straight seam going up one side, over the head, and down the other side).

If using lining, do the following two steps, otherwise skip to attaching the hood.

• Repeat the previous steps to put together the lining pieces.
• Place the lining assembly and the main hood assembly together with wrong sides together, and clip them together along the neck.

Attaching the hood:

• Lay the garment down right-side-out.
• Place the hood around the neckline, with good sides together.
• Clip the two ends of the hood to the slit in the front where the zipper will go, and clip the back seam of the hood to the middle of the back body piece.
• Add additional clips to secure the hood to the neck for sewing.
• Check to make sure that it is assembled correctly.
• Serge/overlock through all layers.

Step 5: Preparing the zipper guard

• Fold the zipper guard in half short ways (so it’s half as wide) with good sides together, and secure it loosely with a clip or two.
• If needed, flip it so that the open seam is on the right side.
• Using your sewing machine and a straight stitch, sew a curve starting vertically at a point along the fold about as far down as the zipper guard is wide, and ending horizontally at the top right corner of the zipper guard. The curve should be shaped such that it forms a smooth corner around the top-left corner of the zipper guard.
• Trim the fabric on the outside of the curve, cutting close to the line of stitching, but not touching it.
• Unclip the fabric and turn it right-side-out, refolding and reclipping the fabric, this time with wrong sides together.
• Serge/overlock down the length of the zipper guard.
• Serge/overlock the bottom of the zipper guard.
• You should have a strip of fabric with a serged/overlocked seam along the right and bottom sides, and a curved corner with a french seam along the top-left.

Step 6: Installing the zipper.

Note: This step is the same with or without lining. Treat the lining and the fashion fabric as one.

• Lay your garment right side out.

• Unzip the zipper.

• Place the zipper good side up along the center seam and align it carefully. The alignment of the top stop is more important than that of the bottom stop, and try not to stretch or gather the fabric as you align your zipper.

• Turn one side of the zipper 1/2 turn outward, and lay it along the open seam so that the tape edge is along the seam and the toothed edge is facing the bulk of the fabric. Line up the edge of the fabric with the edge of the tape and clip in place.

• If sewing swim fabric, sew the fabric and the zipper tape together with a straight stight down each side. This is both to hold things together, and to provide a second, safety line of stitching for the zipper. For less tricky fabrics, this step is optional.

• Turn the zipper back good side up, folding the fabric under in the process.

• Repeat for the other side.

Installing the zipper guard.

• Turn the garment inside-out.
• Place the long serged edge of the zipper guard along the left side of the zipper. The edge of the zipper guard should line up with the tape edge of the zipper and should cover the zipper.
• Adjust the zipper guard vertically. It should extend above the top stop of the zipper by enough so that you can fold the fabric over to hide the zipper pull and protect the neck from the zipper.
• If you’re using a neckband, fold the portion extending above the top zipper stop over to the front of the garment.
• Clip the zipper guard into place. This will cover up the clips holding the zipper to the garment. Remember not to sew over these clips when sewing.

Sewing the zipper.

• Switch to a zipper foot.
• Turn the garment right side out.
• For swim fabric or to have an exposed zipper: Pull the fabric into position, so that the fabric is cleanly folded back from the zipper teeth.
• For fleece fabric or to have a covered zipper: Pull the fabric into position, leaving a small fold of fabric extending over the zipper.
• Place the garment into your sewing machine and adjust the needle so that it is a few mm into the fold of the fabric.
• Start at the neck on the right side, and sew down until you are a few mm past the zipper stop using a straight stitch. Be careful not to sew into the zipper guard or any loose fabric.
• Repeat for the other side. This time, when you reach the bottom, turn the fabric 90 degress and sew across the bottom until you meet the first line of stitching, securing the bottom of the zipper and zipper guard.

Step 7a: (Optional) Ribbed cuffs

The ribbed cuff pieces can be added to the sleeves and legs in a mannar similar to that used to attach the neckband to the neck hole.

• Fold the ribbed cuff piece opposite the fold line (vertically), with good sides together.
• Serge/overlock along the edge, so that the ribbed cuff piece is now a closed loop.
• Unfold the ribbed cuff piece.
• Fold the ribbed cuff piece in half along the fold line (horizontally), with wrong sides together.
• Turn the garment right side out.
• Place the loop of ribbing around the sleeve or leg of the garment, lining up the edges of the ribbing and the sleeve/leg.
• Stretch both the sleeve/leg and ribbing together until the folds/gathers/slack in the sleeve are all gone, and clip into place.
• Serge/overlock on the round along the seam.
• Repeat for the remaining sleeves/legs.

Step 7b: (Optional) Hemming

• Hem the sleeves, legs, hood, and/or bottom of the skirt using a single-fold hem. A coverstitch machine is ideal, but not necessary. Using a twin needle with a regular sewing machine will add some stretch to the stitching, but in either case the use of a stretch stitch is still recommended for high-stretch fabrics.
• You may carefully cutaway excess fabric to make a cleaner hem. This is quite optional, since this fabric should stay on the inside.
• Alternatively, you can overlock or serge the raw edge without folding it over to give it a little bit of substance without adding as much bulk as a folded hem, or you can make a rolled hem.
• Or you can leave the edges unfinished, particularly if it’s swim fabric or some other fabric that does not fray at all.

Step 8: (Options) Adding a skirt

• Fold the skirt piece in half along the cut-on-fold line, with good sides together, and serge/overlock along the side so that the skirt is closed.
• (optional) Hem the bottom of the skirt.
• Gather the skirt along the waist (or top) of the skirt using two gather threads spaced 12mm (1/2”) apart. Place the skirt around the garment where it will rest, and adjust the gathers to fit around the garment.
• The skirt can be either placed right side out on the garment, or inside-out and upside-down on the garment. Right side out will produce a lighter and stronger seam, but the seam will be visible (which may or may not be desirable). Inside-out will hide the seam under the skirt, but will add an extra fold of fabric to the waist.
• Line up the waist of the skirt with where you want it to rest on the garment, and pin it into place.
• Use a coverstitch machine or a short and wide zigzag stitch along the top edge of the skirt, forming a lap seam and hiding the edge of the fabric under the coverstitch or zigzag.
• Make a second coverstitch or zigzag about 6-12mm (1/4” to 1/2”) below the first line of stitching, placing it between the two gather threads and being careful not to catch either gather thread under the coverstitch.
• Remove the gather threads.
• If the skirt was placed inside-out and upside-down, flip it back over.