Internally Threaded Body Jewellery: A Guide for Piercers

Which top fits which post, and when to stop using a part.

By The Tremun Team · Barcelona, Spain

Two internally threaded parts can share a gauge and still not fit. One 1.2 mm (16G) post takes a 0.8 mm thread. Another takes 0.9 mm, and the two are not compatible. A label that says 1.2 mm can mean the bar or the thread.

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What is internally threaded jewellery?

Internally threaded body jewellery has the female thread cut inside the post. The decorative top carries a short male threaded pin that screws into it. Only the smooth outer wall of the post passes through the piercing channel.

According to the Association of Professional Piercers (APP), internally threaded jewellery is part of its standard for initial piercings. Threadless jewellery is an accepted alternative.

Internal vs external thread: what passes through the tissue

On externally threaded jewellery, the thread is cut on the outside of the post. This threaded surface crosses the channel at every insertion and removal.

According to the APP, internal threading removes the risk of sharp threads scraping the tissue. On 1.2 mm (16G) jewellery, an internal thread is about 0.8–0.9 mm. An external thread is 1.2 mm, the full bar.

Keep external thread away from initial piercings. The APP standard does not include it.

1. 1Tissue channel.
2. 2Smooth outer wall of the post. Oro = metal in contact with tissue.
3. 3Female thread, cut inside the post.
4. 4Male threaded pin on the top.
5. 5Top closed onto the post, with no gap.
6. 6External thread, cut on the outside of the bar. It crosses the channel at every insertion and removal.

Anatomy of an internally threaded labret

The female thread inside the post is the weakest point. Inspect it when new stock arrives.

Use these names on orders and drawer labels.

Market sizes. Post lengths run from about 5 to 12 mm (Tremun: 3–12 mm). Disc sizes of 2.5 mm to 5 mm are common. Discs of 3 mm and 4 mm are widely stocked.

Why the female thread is the weak point. It is cut inside a very small hole, and a titanium thread can tear as it is cut. A flaw there is hard to see without a loupe.

What a full specification lists. The Tremun Alba – Mirror polish top lists threading type, material, gauge, setting and contents: internally threaded, titanium ASTM F-136 (Ti-6Al-4V ELI), 1.2 mm (16G), prong set stones, sold without a post.

Threaded tops and posts: which parts fit together

Gauge is the bar diameter. Thread size is the screw diameter. Parts fit only when the threading type and the thread size both match.

Gauge vs thread size

An external thread is the full bar, so it always equals the bar diameter. Internal sizes are common market practice from retailer data, not a standard. Sizes vary by maker.

Other gauges, internal thread only: 1.0 mm (18G) posts usually share the 16G thread; 2.0 mm (12G) posts usually take 1.2 mm; 2.5 mm (10G) and thicker usually take 2.0 mm.

Gauge is an American wire scale. 16G is 1.29 mm, and the trade sells it as 1.2 mm.

Before you order:

1. 0.8 mm and 0.9 mm threads are not compatible. A 16G taper sold with 0.8 mm threading carries a warning. It does not fit the seller’s own 0.9 mm internally threaded labrets.
2. 1.2 mm (16G) and 1.6 mm (14G) posts take different threads at most makers. The usual sizes are 0.8–0.9 mm and 1.2 mm. Check each new supplier.
3. No standards body defines one jewellery thread. Different suppliers sell 0.8 mm and 0.9 mm for the same gauge.

The 1.2 mm trap

1.2 mm is the bar of a 16G post. It is also the common internal thread of a 14G post, and the 16G external thread. A 1.2 mm thread is not a 1.2 mm bar.

Ordering rule: write bar o thread next to every millimetre value on a purchase list.

Parts that are never compatible

• Push pin tops do not fit internally threaded posts. Tremun Labret Posts accept internally threaded tops only.
• Internally threaded tops do not fit push pin posts. The Tremun Labret 2.0 Push Pin accepts push pin tops only.

Parts from different brands

Suppliers state that one company’s parts may not fit another company’s parts. A US maker notes there is no industry-standard thread pattern for 16G. A top can screw in and still leave a gap.

Fit test. Before sterilisation, turn one top into one post from the two sources, by hand. Reject any pair that feels rough, gets stuck or shows a gap.

Fitting the jewellery

Start every top by hand, in line with the post. Stop at the first resistance.

How to use a threaded insertion pin

A threaded insertion pin screws into the post and tapers to a point. The post follows it, so no edge enters the channel.

Use a threaded insertion pin in six steps:

1. Match the insertion pin. Same gauge and thread size as the new post. A mismatched taper can cause more damage than no taper.
2. Test first. Screw the insertion pin into the new post before the old jewellery comes out.
3. Sterilise the insertion pin with the set. It enters the channel, so treat it as jewellery.
4. Keep the channel occupied. If the old piece comes out too early, the channel can be hard to find. Push the old jewellery out with the tip of the insertion pin.
5. Guide the post through until the disc rests on the tissue. Do not push against resistance.
6. Hold the disc, unscrew the insertion pin, fit the top. The post does not turn in the channel.

1. 01Screw the threaded insertion pin into the new post.

2. 02Put the tip of the insertion pin against the old jewellery. Push the old jewellery out.

3. 03The post follows the insertion pin until the disc rests on the tissue.

4. 04Hold the disc. Unscrew the insertion pin. Turn the top until it sits fully against the post.

Tremun Threaded Insertion pins (Titanium) come in 1.2 mm (16G) and 1.6 mm (14G).

Starting the thread

Cross-threading starts when a thread enters at an angle. It damages the thread flanks permanently. To start a thread:

1. Hold the top in line with the post.
2. Turn it anticlockwise (to the left) until you feel or hear a small click. The two threads are now aligned.
3. Turn clockwise, slowly, by hand.
4. Stop if it is hard to start. Unscrew, realign and restart. Never force the first turn.

How tight is tight enough

Studio practice: clean, dry threads. Fingers only, no pliers. Turn until no gap shows between top and post, then stop.

There is no published torque value for body jewellery that we know of. According to the APP, threaded parts should close with no gap. Titanium threads can gall (cold-weld) when forced, so never turn past resistance.

When to downsize: change the post, keep the top

The usual recommendation for the first downsize is 4 to 6 weeks. Two weeks is too early for any placement. This timing is a suggestion only: the piercer always checks the piercing in person and decides when to downsize, because everyone heals differently.

Signs to check include a post that moves, gets caught in hair or towels, or leaves a visible gap between the top and the skin. The signs matter more than the number of weeks.

In most downsizes only the post length changes, and the same top is kept. Use a taper or a transfer tool.

For the healing side, read Etapas de cicatrización del piercing y cuidados posteriores.

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The top can usually stay. Tremun tops are sold without posts, so you order only the shorter Labret Post 16G – Mirror polish. Labret Posts come in 3–12 mm.

Inspecting threads before use

Check every thread under a 10× loupe. A thread that feels rough is a reason to retire the part.

Stripped threads come from over-tightening, cross-threading or under-tightening. Some consumer pages suggest glue or threadlocker. In the studio, replace the part instead.

Internally threaded vs threadless: when each makes sense

Both systems are acceptable for initial jewellery. Push pin changes are faster. A threaded top does not depend on how a push pin is bent.

For the full comparison, read Labrets de titanio planos o sin rosca: ¿cuál es mejor?

Material and documentation: ASTM F-136 and mill certificates

Check the certificate of the post, not only the top. The post is the part inside the channel.

Titanium standard. Implant-grade titanium (Ti-6Al-4V ELI) is specified by ASTM F136 or ISO 5832-3. The APP accepts both for initial piercings.

What a certificate proves. A mill certificate shows the grade of a metal batch. The APP notes that it cannot prove that one piece came from that batch. Ask every supplier for the certificate, the standard and edition it cites, and the finish.

EU rules. The REACH limit is on nickel release, not nickel content. No EU rule requires internal threading: it is professional practice.

For more on the metal, read why titanium is the best material for piercing jewellery.

Building an internally threaded stock

Label every drawer by bar size and thread size, never by gauge alone.

Tremun tops and posts are sold separately. One range of posts serves all Tremun titanium 1.2 mm (16G) threaded tops.

1. Use one thread system per gauge. Fewer thread sizes mean fewer wrong fittings.
2. Stock 14G only if you fit 14G. Ask us which tops fit the 1.6 mm (14G) post before you order.
3. Choose the disc by anatomy. Tremun Labret Posts have a 4 mm flat disc. The Micro Labret has a 3 mm disc for tight spots.
4. Cover every length. Keep a run of lengths for initial and downsize posts, for example 5 to 12 mm in 1 mm steps.

The Tremun Team · Barcelona, Spain

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