Air threading is worth paying for if you change serger threads often, find the lower looper hard to reach or see, or suspect that a fiddly machine would end up unused in a cupboard. It is not worth it if you serge in one or two thread colors, are happy with the tie-on method for changing them, and would rather put the difference toward a better-built manual machine. The advantage is real but narrow: it concerns the two loopers only, and the needles are threaded by hand on both types.
| Feature | Air threading | Manual threading |
|---|---|---|
| Looper threading | Thread end placed at a port, a lever or button sends it through with air | Thread guided by hand along color-coded guides, with tweezers at the looper eye |
| Needle threading | By hand, usually with a built-in threader | By hand, usually with a built-in threader |
| Threading order | Any order on most models | Fixed order, loopers before needles |
| Lower looper thread break | Re-thread that looper only | Re-thread the lower looper, then both needles |
| Thick or decorative threads | Some need a threader wire or the tie-on method | Pass through the guides as any other thread |
| Price tier | Mid-range and above | Entry-level to premium |
| Mechanism to maintain | Air pump, valves and looper tubes | Guides only |
What is the difference between air threading and manual threading?
A serger forms its stitch with one or two needles and two loopers. The loopers carry thread over and under the fabric edge, and the lower looper runs below the needle plate, through a path you can only partly see. On a manual machine you follow the colored guides printed on the machine, in the order the manual gives, and finish each looper by pushing the thread through its eye with tweezers. The lower looper is the step people dread.
On an air threading machine the looper paths are hollow tubes. You lay the thread end at the entrance port, press a lever or a button, and a burst of air carries the thread through the tube and out of the looper eye in a second. The system was pioneered by Baby Lock under the name jet-air threading and is now also offered by Juki, Brother, Janome and Bernina on some of their models, at the time of writing (October 2026). The needles are still threaded by hand on every one of them, though most include a needle threader.
How hard is it to thread a manual serger?
Less hard than its reputation, once you have done it a few times. A first threading with the manual open takes 15 to 20 minutes. After a month of use, a full re-thread from empty takes two to three minutes, most of it spent on the lower looper. Many manual sergers help there: a lever swings the lower looper forward, or a small threader on the looper catches the thread so you do not need to see the eye at all.
Changing colors is faster still with the tie-on method. Cut each thread above its spool, tie the new thread to the old with a small, tight knot, lift the presser foot or set the tensions to zero, and pull the old threads gently from behind the foot until the knots have come through the loopers. At the needles, cut the knot off and thread the eye by hand, because a knot will not pass through a needle eye. Done this way, a color change takes about as long as on an air threading machine.
Where manual threading does hurt is a thread break in the lower looper. On almost every manual serger, the lower looper must be threaded before the needles, otherwise the needle threads sit under the looper thread and the stitch will not form. So a lower looper break means unthreading both needles, re-threading the looper, then threading the needles again. Air threading machines let you thread in any order, which turns that ten-minute job into a one-minute one.
What does air threading not do?
It does not thread the needles, and it does not set the tensions, the stitch width or the differential feed for you, which are the settings that decide whether a seam lies flat or waves. A badly set air threading serger produces the same tunneled, puckered or loopy seam as a badly set manual one.
Thick decorative threads are its weak spot. Wooly nylon, heavy metallics and 12-weight cotton do not always travel through the tubes on the first try; the usual answers are to cut the end cleanly at an angle, to blow a length of regular thread through first and tie the heavy thread to it, or to use the threader wire that comes with the machine. If decorative serging is the reason you want a serger, the tube is one more thing to work around rather than a shortcut.
Finally, there is more inside the machine. The air pump, its valves and the looper tubes are reliable parts, but they are parts that a manual serger does not have, and a service costs accordingly. Lint can settle in a tube over the years; blowing it clear with the machine's own air usually fixes it.
Which serger features matter more than threading?
Threading happens at setup. The features below are at work in every seam, and a manual serger that has them will sew better clothes than an air threading one that does not.
- Differential feed. Two sets of feed dogs that move at different rates, so you can stretch or gather the fabric as it is sewn. Without it, knits wave and lightweight wovens pucker. Every serger for garments should have it.
- Adjustable cutting width and stitch length, with a scale you can read, so you can return to a known setting.
- A retractable stitch finger for switching to a rolled hem without changing the needle plate.
- A free arm for hemming sleeves and trouser legs, and for the underarm of a T-shirt.
- Lay-in tension discs or dials you can reach, a bright light, and a knife that disengages for sewing without trimming.
- A 2-thread conversion for finishing fine fabrics without bulk.
The guide to choosing a serger for beginners walks through those features in detail, and serger vs sewing machine explains what a serger cannot replace. If the budget only stretches to a basic manual model with differential feed, that is the better buy, and finishing seams without a serger covers you until then.
Which should you choose?
Choose air threading if you sew many projects in different colors and re-thread the loopers every week; if a hand tremor, arthritis or eyesight make the tweezers-and-looper step genuinely difficult; if you have owned a manual serger before and used it less than you meant to because of threading; or if you already know you want a mid-range machine and the air threading model costs little more than the manual one beside it.
Choose manual threading if this is your first serger and you want to spend on differential feed, a solid frame and a good knife rather than convenience; if you mostly serge in neutral colors and change thread rarely; if you like decorative threads in the loopers; or if you are buying second-hand, where manual machines are plentiful and cheap to service.
Either way, learn the tie-on method in your first week, keep the manual's threading diagram near the machine, and thread with the presser foot up and the tensions released. The machine you thread without dread is the one you will use, and that is the real decision this comparison turns on.