Earring Backs Explained: Butterfly, Screw, La Pousette and Locking
The back is the part of an earring nobody thinks about until a diamond stud is gone. Every style holds the earring on by a different mechanism, and the mechanism decides how it fails. Worth ten minutes before you put something valuable in your ears.
Butterfly, the default nobody chooses
The friction back, also called a butterfly or push back, is what most earrings ship with. A flexible ear nut slides over the post and grips it. That is the whole system. Nothing locks. It stays on because the metal squeezes the post.
The failure mode follows directly. Squeeze a piece of springy metal onto a post a few thousand times and it stops squeezing as hard. Jewelry Designs states the consequence plainly: over time the flexible ear nuts can loosen, so they are not advisable for heavy or high value items.
We are not telling you to throw them out. For light everyday studs they are fine, and they are quick to put on. But if a butterfly back slides off the post with almost no resistance, it is finished. A replacement back costs very little compared to the earring it is holding.
Screw backs, a real lock with a real trade-off
A screw back uses a threaded post cut from the appropriate precious metal, with a clutch tightened along the thread until it is snug. This is a positive mechanical lock. The clutch cannot come off unless it is turned.
The trade-off is comfort, and it is a genuine one. The corrugated surface of the threaded post can irritate sensitive skin along the ear. A thread is a ridged surface being passed through a hole in your body. Some people never notice. Others cannot wear them.
The other cost is time. Screwing a back on and off is slower and more fiddly, especially with cold hands or long nails. For a stud you wear continuously that is irrelevant. For earrings you change daily it becomes annoying fast.
La Pousette, the one worth knowing about
This is the mechanism most people have never heard of and often prefer once they try it. Squeezing two small tabs in the clutch lets it pass smoothly over the post, then it locks securely into position on release.
The advantage is that it combines things the other two cannot. It is a positive lock like a screw back, so it does not rely on friction that fades. But it runs on a smooth post, so you avoid the threaded surface that irritates sensitive ears. It is also faster to operate than a screw back once your fingers learn it.
The catch is cost and availability. These are a more complex finding and they are not what a mass-market stud ships with. They can usually be fitted to existing earrings, which is the route most of our customers take when they want to secure studs they already own.
Post thickness, and the gauge confusion
Post thickness is quoted in gauge, on the Birmingham scale, where a lower number is thicker. 14G is 2.108 mm, 16G is 1.651 mm, 18G is 1.270 mm, 20G is 0.9081 mm and 22G is 0.7176 mm. The steps are not linear and vary, so you cannot interpolate between them.
Thinner is not automatically gentler. The Association of Professional Piercers warns that the body may treat jewellery that is too thin in gauge like a splinter, resulting in migration or rejection. A very fine post can cheese-wire through tissue rather than sit in it.
For anything going into a piercing that is not fully healed, material standards matter and the APP names them precisely: implant certified titanium meeting ASTM F-136, ASTM F1295 or ISO 5832-3, or commercially pure titanium meeting ASTM F-67, and for steel ASTM F-138 or ISO 5832-1. Vanhess sells piercing jewellery and does not perform piercings, so for the piercing itself see a professional studio. Our guide to metals for a new piercing covers the materials side.
Threading direction matters more than you would think
On body jewellery the APP recommends internally threaded or threadless posts, where the part passing through your skin is smooth and the threads sit on the removable end. Externally threaded posts have the screw pattern cut into the post itself, so this comparatively rough surface may be passed through the tissue.
It is the same principle behind why screw-back studs bother some ears. A threaded surface dragged through a hole in your body is more abrasive than a polished one.
A note on jewellery for children
If you are buying for a child, Canadian law sets hard limits rather than guidance. Jewellery marketed to children under 15 must not contain more than 90 mg/kg of lead, and items small enough to fit in the small parts cylinder must not contain more than 130 mg/kg of cadmium. Solid gold and implant-grade titanium clear this comfortably. Cheap fashion jewellery is where the risk sits. Our piece on ear piercing for kids covers the wider picture.
Key Takeaways
- Butterfly backs hold by friction alone and loosen with use. Jewelry Designs advises against them for heavy or high value earrings.
- Screw backs give a positive lock, but the threaded post can irritate sensitive skin.
- La Pousette backs lock on release and run on a smooth post, combining security with comfort.
- Post gauge is Birmingham scale: 18G is 1.270 mm, 20G is 0.9081 mm, and the steps are not linear.
- Too thin a post can be treated by the body like a splinter, causing migration or rejection.
- Canadian law caps lead at 90 mg/kg and cadmium at 130 mg/kg in children's jewellery.
Pieces from the shop
Frequently Asked Questions
Which earring back is the most secure?
Mechanically, anything with a positive lock beats anything relying on friction. That means screw backs and La Pousette style locking clutches sit above butterfly backs, because a butterfly holds only by gripping the post and that grip weakens every time you use it. Between the two locking types the choice is about comfort rather than security. A screw back has a threaded post, which some people find irritates the ear over a long day. A La Pousette locks on release but runs on a smooth post, which is why we usually suggest it for people with sensitive ears who still want their studs held properly. We should be honest that we found no laboratory comparison measuring retention force across back types, so treat any specific percentage claim you see online with suspicion.
Why do my earring backs keep falling off?
Almost always because the butterfly backs have lost their spring. They work by squeezing the post, and metal that gets flexed thousands of times stops squeezing as firmly. Once a back slides on and off with barely any resistance, it is not going to hold a stud through a day of getting knocked by a collar, a phone or a pillow. The good news is that replacement backs are inexpensive relative to the earrings they protect, so there is no reason to keep using tired ones. If you keep losing the same earring, that is the moment to switch to a locking back rather than replacing like for like. We can often fit locking clutches to studs you already own, so you do not have to buy new earrings to solve it.
Do screw back earrings hurt sensitive ears?
They can, and the reason is physical rather than allergic. A screw back needs a threaded post, and that thread is a ridged surface being passed through a hole in your earlobe. Jewelry Designs notes directly that the corrugated surface of threaded posts can irritate sensitive skin along the ear. Plenty of people wear them for years without noticing anything. Others find they get soreness that a smooth post never caused. If that is you, a La Pousette or similar locking clutch gives you the same security on a smooth post, which usually solves it. It is also worth ruling out a metal reaction separately, since nickel sensitivity produces similar symptoms for an entirely different reason and needs a different fix.
What gauge should an earring post be?
For a healed lobe, most fine jewellery studs sit in a range that is comfortable without being so fine that it cuts. Post thickness is quoted on the Birmingham gauge scale, where a lower number means thicker metal: 18G is 1.270 mm and 20G is 0.9081 mm, and the increments between sizes are not linear, so you cannot estimate between them. Going very thin is not the safe choice it sounds like. The Association of Professional Piercers warns that jewellery too thin in gauge may be treated by the body like a splinter, which can cause migration or rejection. For a piercing that is not fully healed, the material standard matters more than the gauge, and the APP names specific standards including ASTM F-136 titanium. Come in and we will measure what your current earrings use.
Sources
- Jewelry Designs, "Earring Backs"
- Wikipedia, "Birmingham gauge"
- Association of Professional Piercers, "Jewelry for Initial Piercings"
- Justice Laws Canada, Children's Jewellery Regulations (SOR/2018-82)
Sources retrieved September 2026. If something here has gone out of date by the time you are reading it, tell us and we will fix it. We keep these guides current as the trade changes.
Visit Vanhess
Bring your studs in and we will check whether the backs still grip properly, and fit locking clutches if they do not. It is a small job that has saved a lot of diamonds. See our earrings or the piercing jewellery guide, or call (604) 653-6449.
