How to Add Snaps to a Baby Romper (KAM Snaps and Metal Snaps)
The short answer: to add snaps to a baby romper, reinforce the snap area with interfacing or a double layer of fabric, and mark every snap position on both edges before you set anything. Push a snap cap through from the right side, then press the socket onto the underside of the top edge and the stud onto the right side of the bottom edge. Test the whole set-up on a scrap first.
Snaps are what make rompers, dungarees and baby sweaters practical. They mean fast nappy (diaper) changes and easy dressing over a wobbly head. They look intimidating because there are several small parts, and they all have to line up. Marina, the tailor behind Frocks & Frolics, admits that when she first drafted the Lollipop Romper, she put her snaps in wrong, even after years of sewing professionally. This guide helps you avoid the same mistake.
Plastic snaps vs metal snaps
| Plastic resin snaps (e.g. KAM snaps) | Metal prong snaps | |
|---|---|---|
| Parts | Cap, socket (female) and stud (male) | Prong ring, socket and stud, or decorative cap |
| Tool | Hand pliers or a table press | Setting tool, pliers or a hand press |
| Best for | Rompers, sweaters, bibs and back closures. They're light, come in lots of colours, and won't rust. | Heavier fabrics and a classic metal look. The prongs grip knits without needing a hole cut first. |
| Watch out for | You need a clean hole for the cap's prong | Prongs can bend if the fabric is too thick or the snap isn't set straight |
Frocks & Frolics patterns that use snaps call for KAM snaps or snap poppers, so either type will work. Plastic snaps are the easiest place to start.
What size snaps for baby clothes?
For plastic snaps, size 20 (also sold as T5) is the standard size used on baby clothes, and it's the size most starter kits include. Smaller sizes are available for very fine fabrics and doll clothes. Whichever size you choose, use the same size for the cap, socket and stud in each set.
What you'll need
- Snaps: count the positions on your pattern and add a few spares
- Snap pliers or press (plus an awl if your kit doesn't include one)
- Fusible interfacing suitable for knits, or the placket or binding your pattern uses
- A fabric marker or chalk
- Scraps of your garment fabric for a test snap
How to add snaps to a romper, step by step
Step 1: Reinforce the snap area
Never set a snap through a single layer of knit. It will pull out as soon as someone tugs on it. Snaps belong on a placket, a facing, a binding or a double layer backed with interfacing. That's why the Lollipop Romper has a snap placket on the inner leg, and the Dungies Romper pattern asks for knit interfacing at the shoulder closure.
Step 2: Work out which edge overlaps
Before marking anything, close the opening the way it will be worn and note which edge sits on top. The socket goes on the underside of the top edge. The stud goes on the right side of the bottom edge, so the two meet when you close it. This is the step most people get wrong.
Step 3: Mark the positions on both edges together
Use your pattern markings where they're given. If there aren't any, space the snaps evenly, keeping the first and last close to the ends so the opening doesn't gape. Lay both edges together, overlapped as worn, and mark straight through so the positions match.
Step 4: Make the hole
For plastic snaps, pierce a small hole at each mark with an awl or the point on your pliers. Keep it small. The prong only needs to pass through, and a large hole weakens the fabric.
Step 5: Set the socket side
Push a cap through the hole from the right side of the top edge. Place a socket over the prong on the wrong side, then press firmly with the pliers until the prong flattens into a smooth dome.
Step 6: Set the stud side
Repeat on the bottom edge, from the wrong side through to the right side, finishing with a stud. Close the snap and check that it clicks together and pulls apart cleanly.
Step 7: Test before you commit
Set one test snap on scraps with the same layers and interfacing as your garment. Once it holds and releases cleanly, you're ready to do the real thing.
Troubleshooting
- The snap pulls out of the fabric: the area needs more support. Add interfacing or another layer.
- The cap spins or wobbles: the prong wasn't pressed flat enough, or it's too long for thin fabric. Squeeze again, or use a thicker layer.
- The snap won't close: the socket and stud may be on the wrong sides (see step 2), or the marks don't line up.
- The fabric puckers around the snap: the hole is too big, or the fabric was stretched while you set the snap.
The optional KamSnap back closure on the Natalie Sun Dress.
Snaps or buttonholes?
Snaps are quick and easy for anyone who dreads buttonholes, and they're gentler for fidgety babies. Buttonholes suit wovens and give a more traditional look. Several Frocks & Frolics patterns let you choose. For example, the Natalie Sun Dress has an optional KamSnap back closure. To see both methods demonstrated, including a front placket that mixes KamSnaps and buttons, visit the buttonholes, plackets and snaps video library.
The Lollipop Romper has a snap placket on the inner leg for quick nappy changes.
Patterns that use snaps
- Lollipop Romper: snap closure on the inner-leg placket, 0–3 years
- Dungies Romper: KamSnap closure at the shoulders, newborn–3 years
- Jelly Bean Sweater: optional shoulder snaps, or leave them out for an easier make
- Bobby Dazzler Dungarees: optional snap placket for nappy changes
- Daisy Knit Dress and Amelie Dress: KAM-snap closures
Before you start sewing, read our guide to choosing knit fabric for baby clothes. The right fabric weight makes snaps much easier to set.
Frequently asked questions
Can you put snaps on stretchy fabric?
Yes, as long as the snap area is stabilised with knit interfacing, a placket or a binding. Without that support, the fabric stretches and the snap pulls through.
Are KAM snaps safe for baby clothes?
Plastic snaps are widely used on baby clothes. Set each one firmly, check them regularly, and replace any that loosen, as you would any small fastening on children's clothing.
Do I need a snap press, or will pliers do?
Hand pliers are fine for the handful of snaps on a romper. A table press is faster and gives more consistent results if you sew baby clothes regularly.
How do I remove a snap I put in wrong?
For plastic snaps, carefully cut through the flattened prong with small snips or flush cutters, then remove both halves. Fuse a small patch of interfacing behind the spot before setting a new snap, because the old hole will be weaker.