Com-pleat your seat
An introduction to pleats
Pleats for auto upholstery can come in many styles and are most often used in the inserts of seats. At their most basic, the pleats will only be a few stitch lines on the face. This is usually to allow a fold or to hold the listing. (Listings are pockets holding a piece of wire, used to pull the cover down into the seat foam.) At their most intricate, the pleats will create a pattern on otherwise plain materials.
Last month we introduced you to five common seams used when trimming a car. Like seams, pleats can be nothing more than a style choice. So, let’s look at 7 pleat types and what happens to create them. Typically, a trimmer uses the following formulas as a starting point for a test piece. This way they can ensure they get the exact size needed with your chosen materials.
Top-sewn pleats
The simplest type of conventional pleat is the top-sewn pleat. Here, the material is laid over sew foam and sewn to the width wanted. Trimmers will mark to the finished width, plus an allowance to allow the foam’s thickness to crush. If not allowed for, the finished size will be slightly smaller than intended. For example, this can mean an insert with 10 pleats could end up more than an inch shorter than needed. Trimmers offering better quality results will also have a piece of calico glued under the foam before sewing. This makes each pleat look slightly deeper.
Top-sewn pleats can run either front-to-back or side-to-side. Just this change in direction can change the look of the interior. Sometimes, the pleats are sewn diagonally, such as in the VK/VL Calais and ZK Fairlane.
Deep top-sewn pleats
These are sometimes called sewn-in-the-ditch pleats because of how they’re made. For this pleat type, a thicker foam is used than sew foam. At least ¾ inch, but sometimes one inch may be chosen. This foam is glued to a piece of calico, then slit right the way through at the desired pleat width. Care must be taken so that the calico isn’t cut though. The material is then marked on the face at the correct pleat width, which requires a bit of easy maths. Add the desired pleat width to 2 times the foam height, then subtract ¼ inch. This allows for a bit of foam crush.
Sewing begins by joining the pieces by sewing a line on the edge parallel to the pleats. The first pleat will be sewn by lining up your marked line with the cut in the foam. Carefully stitch along this line while gently holding open the foam so that the needle is unobstructed. Repeat for all pleats on each piece.
These are usually run front-to-back on a seat. The pressure of the body pushing on side-to-side pleats would eventually damage the foam. Usually, these pleats aren’t used on door trims or other surfaces, only seats. The deep foam adds a softer, more luxurious feel, so it’s perfect on seats in luxury cars.
Back-sewn pleats
Back-sewn pleats are a step up from the top-sewn pleats described above. These pleats require a little more work, and a little more material to create. They start out exactly the same, with the material laid over sew foam and calico. The difference is that an extra ½ inch is required between each pleat’s finished size.
Sew along your marked line just like a top-sewn pleat. When all top sew lines are sewn, each pleat is folded along the stitch line and sewn again. This extra stitch line is placed ¼ inch in from the fold, on the back side. When completed and opened on the face, a seam will be visible rather than a stitch line.
Back-sewn pleats look slightly plumper than top-sewn pleats given the same foam thickness. The extra work and materials do mean a slightly higher price though. If thinner-width pleats are used, this means more pleats, so slightly higher may be much higher!
A variation of the back-sewn pleat may include different colours being used. This will be added just like an extra panel. Like top-sewn pleats, back-sewn pleats can run front-to-back or side-to-side.
Back-sewn tuck-n-roll pleats
Think of these pleats as a hybrid of back-sewn pleats and sewn-in-the-ditch pleats. These pleats require even more work but add a period-correct look to certain vehicles. Here, calico-backed foam is marked to the pleat’s finished size before being slit down to, but not including the calico. Marking the material needs another bit of maths. They will add 2 times the foam height, plus a ¼ inch to the required finish size of each pleat. This allows for a folded ¼ inch sew allowance and a little foam crush. Each of these pleats is marked on the back, not on the face of the material.
Sewing ¼ inch in from the fold line, place the fold hard against the slit line in the foam. This causes the foam to crush below the stitch, creating the desired tuck-n-roll appearance.
Stuffed tuck-n-roll pleats
Stuffed tuck-n-roll pleats are the traditional pleat style, dating back to horse-drawn carriages. Of course, modern trimmers will mostly use foam and underfelt as the stuffing. But for authenticity, sometimes cotton wadding will still be used. Marking the material for stuffed tuck-n-roll pleats is the same as for back-sewn tuck-n-roll. The difference is the backing. The calico is marked to the pleat’s finished size; the material is sewn onto this without any foam.
Sewing ¼ inch in from the fold line, place the fold hard on the line on the calico. Once all pleats have been sewn to the calico, channel tins will be used to stuff the pleat. The tins used for cotton wadding and foam are slightly different, but how they work is the same. The filling is compressed between the two pieces of the tool and inserted into the pleat. Then, the tin is removed, leaving the filling behind.
Diamond pleats
The perennial favourite is diamond stitched pleats. Seen in everything from pedal cars and race cars to high-end luxury cars like Bentleys, diamonds refuse to die out. These are technically a quilting technique, not pleats, but they are used in the same places. Like top-sewn pleats, the material is marked, then laid on top of sew foam and calico before being sewn. Again, an allowance needs to be made to allow for the thickness of the foam. That is if the diamonds are to have a puffy, filled look. Sizing the diamonds is important, trimmers will try to have a full diamond on either side of an insert. Because of this, every job is different and tailored to the specific seat.
Diamond stitched pleats can be sewn with one stitch line or two, be a traditional diamond or curved. Some are stretched to be long diamonds, while others are shrunken, and are more like squares than diamonds. A luxurious diamond will be puffy, whereas, in a sportier environment, flatter looks more in place.
Beyond diamonds
Adventurous trimmers like to look beyond diamonds, and the possibilities are endless. Hexagons have been gaining popularity but with CNC quilting machines, the brave client can get something unique. Hourglass patterns, waves, fish scales, often budget, bravery, and imagination are the limits.
Pleat dreams
Now you know some different pleats for auto upholstery, and how much labour goes into each. With any luck, this can help you and your trimmer find the perfect design for your new interior. Like other aspects of interior design, colour, texture, and style play a part in helping keep things cohesive. You’re sure to find something that fits you, and your ride, perfectly.
Feeling inspired? Located halfway between Brisbane CBD and the Sunshine Coast, we are perfectly positioned to be your partner in comfort and style. Call HSKG to make an appointment today.