![[Experiment] Prompts for Long Nipples | 75 Images of Thorough Testing](/tips/nipple-length-descriptor-test/cylinder_0_0_0000_1787699347943046438.webp)
Conclusion First
long nipples doesn’t work. Neither does erect nipples or protruding nipples. After testing 24 conditions and 75 images, only 2 prompts successfully produced protruding nipples.
And trying to emphasize that effect with huge or :1.5 causes it to disappear instead. This is the opposite result from breast size testing, where oversized could additively increase the effect.
Prompts That Worked (Only 2)
Prompts That Didn’t Work (All 22 Other Conditions)
long nipples, protruding nipples, erect nipples, puffy nipples, pointy nipples, elongated nipples, large nipples, long protruding erect nipples (stacking), (long nipples:1.5) (weighting), tubular nipples, pencil eraser nipples, bullet nipples, swollen erect nipples standing out prominently, hard nipples pointing forward, nipples, not inverted, not flat, thick protruding nipple tips, extremely long nipples sticking out, huge cylindrical nipples protruding from areola, (small cylindrical nipples protruding from areola:1.5), (small cylindrical nipples protruding from areola:2.0), (huge cylindrical nipples protruding from areola:1.5), very long cylindrical nipples protruding far from areola
Experimental Design
| Item | Value |
|---|---|
| Model | z-image-turbo (6B, photorealistic distilled) |
| Steps | 8 |
| CFG | 1.0 |
| Size | 1024x1024 |
| Seeds | 3 fixed seeds (common across all conditions) |
| Per condition | 3 images |
| Total | 24 conditions + control = 75 images |
Base Prompt
Only the {VARIABLE} portion is swapped — everything else is identical.
Control (No Variable)
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
Nipples are nearly flat relative to the areola. This is the baseline.
Worked: small cylindrical nipples protruding from areola
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
3/3 nipples clearly protrude cylindrically from the areola. The only condition with consistent effect across all 24 conditions.
The reason it works lies in the combination of 3 elements:
cylindrical— geometric shape specificationprotruding from areola— explicitly specifies what protrudes from wheresmall— limits size reference (changing this tohugebreaks it, as described later)
Worked: nipples poking out like thimbles
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
3/3 rounded protrusions. However, breast size becomes smaller than control as a side effect.
The combination of poking out (action of sticking out) + thimbles (thimble = concrete object metaphor) works.
Didn’t Work: Simple Adjectives (7 Conditions)
Tried intuitive prompts one after another. All failed.
long nipples — No Effect
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
No change to nipples. Composition changes (cloth-holding poses) with more impact on framing than nipples.
protruding nipples — No Effect
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
Just shifts to a breast close-up. Nipples unchanged from control.
erect nipples — No Effect
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
Same close-up shift as protruding.
puffy nipples — Doesn’t affect nipple length
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
Tendency for the areola to dome outward, but that’s “puffiness,” not “length.” Different goal.
pointy / elongated / large nipples — All No Effect
pointy nipples:
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
elongated nipples:
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
large nipples:
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
3 conditions, 9 images, all identical to control.
Didn’t Work: Stacking, Weighting, and Metaphors (5 Conditions)
long protruding erect nipples (stacking) — No Effect
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
Stacking worked in breast size testing. It doesn’t work for nipples. Stacking adjectives that don’t work individually still doesn’t work.
(long nipples:1.5), (protruding:1.3) — No Effect
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
Weighting syntax has limited influence at CFG=1.0.
extremely long nipples sticking out — Slight Effect
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
Slight protrusion at nipple tips visible in 3/3. The action description sticking out may be contributing. However, clearly weaker than the top 2 conditions.
tubular / pencil eraser nipples — No Effect
tubular nipples:
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
pencil eraser nipples:
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
tubular affects breast shape but not nipple length. pencil eraser is not associated with nipple shape by the model.
Didn’t Work: Other Specific Expressions (5 Conditions)
bullet nipples / swollen erect nipples / hard nipples pointing forward / not inverted, not flat — No Effect
bullet nipples:
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
swollen erect nipples standing out prominently:
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
hard nipples pointing forward:
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
nipples, not inverted, not flat:
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
bullet nipples— No effectswollen erect nipples standing out prominently— stacking adjectives without concrete shape specification has no effecthard nipples pointing forward—pointing forwardis misinterpreted as a finger-pointing posenipples, not inverted, not flat— negation expressions don’t work at CFG=1.0
thick protruding nipple tips — Unstable
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
Unstable with only one side protruding. Low reproducibility — not practically useful.
Lab Director Comment: 24 conditions and only 2 worked — and even those break when you try to emphasize them. It’s like a puzzle.
cylindricalas a geometric shape description works whilelongdoesn’t — that’s actually a useful insight into prompt design philosophy.
Emphasizing the Working Prompt Breaks It
We’ve confirmed that small cylindrical nipples protruding from areola is the most effective. So what happens if you change it to huge or add :1.5?
Answer: All completely backfire. The effect disappears entirely.
huge cylindrical nipples protruding from areola — Effect Disappears
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
Just changing small → huge causes the protrusion to disappear. 3/3 flat.
(small cylindrical nipples protruding from areola:1.5) — Effect Disappears
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
Adding weight 1.5 causes the protrusion to disappear. 3/3 flat.
(small cylindrical nipples protruding from areola:2.0) — Effect Disappears
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
Weight 2.0 also causes disappearance. Higher weight doesn’t mean better effect.
(huge cylindrical nipples protruding from areola:1.5) — Effect Disappears
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
huge + :1.5 double emphasis. Still no effect.
very long cylindrical nipples protruding far from areola — Effect Disappears
| seed 0 | seed 1 | seed 2 |
|---|---|---|
 |  |  |
Changed small → very long, protruding → protruding far. Effect disappears.
Complete Condition Effect Summary
| Condition | Effect | Notes |
|---|---|---|
| small cylindrical nipples protruding from areola | Works | Only stable effective condition |
| nipples poking out like thimbles | Works | Side effect: breasts become smaller |
| extremely long nipples sticking out | Faint | Only slight protrusion |
| thick protruding nipple tips | Faint | Unstable (1–2/3) |
| puffy nipples | Different effect | Puffiness but not length |
| long nipples | No effect | |
| protruding nipples | No effect | |
| erect nipples | No effect | |
| pointy nipples | No effect | |
| elongated nipples | No effect | |
| large nipples | No effect | |
| long protruding erect nipples | No effect | Stacking invalid |
| (long nipples:1.5), (protruding:1.3) | No effect | Weighting invalid |
| tubular nipples | No effect | |
| pencil eraser nipples | No effect | |
| bullet nipples | No effect | |
| swollen erect nipples standing out prominently | No effect | |
| hard nipples pointing forward | No effect | Misinterpreted as finger-pointing pose |
| nipples, not inverted, not flat | No effect | Negation invalid |
| huge cylindrical nipples protruding from areola | Backfires | Original effect disappears |
| (small cylindrical … :1.5) | Backfires | Original effect disappears |
| (small cylindrical … :2.0) | Backfires | Original effect disappears |
| (huge cylindrical … :1.5) | Backfires | Original effect disappears |
| very long cylindrical … protruding far | Backfires | Original effect disappears |
Why This Happens
1. Why Abstract Adjectives Don’t Work in z-image-turbo
z-image-turbo is a distilled model at CFG=1.0. In normal models (CFG 7–11), a strong force of “get closer to this prompt” operates, but at CFG=1.0 that force is nearly absent.
As a result:
- Abstract adjectives like
long nipplesare ignored - Only the combination of concrete visual information like
cylindrical+protruding from areolacould elicit nipple protrusion
This is the same conclusion as in the coherent anatomy testing, and is a principle that applies to z-image-turbo prompts in general.
2. Why Emphasizing Breaks It
small cylindrical nipples protruding from areola is effective, but any modification causes the effect to disappear.
- Changing
small→hugeeliminates the effect - Adding
:1.5weight eliminates the effect - Adding
very longorfareliminates the effect
For breast size, stacking additively increases the effect. For nipple protrusion, the effect is only achieved under specific prompt conditions and is very fragile to changes. The reason is unclear, but based on experimental results, breast size allows for continuous control while nipple protrusion is only achievable in very limited conditions.
3. Compositional Impact
Adding nipple-related tokens changes the composition:
- Breast close-up shift:
protruding,erect,pointy,large,bullet - Arms spread wide pose:
puffy,elongated - Cloth-holding pose:
long
The reason is unclear, but adding nipple-related tokens tends to change the composition. Wanting to change nipple shape but getting a composition change instead is an unintended side effect.
Comparison with Other Tests
| Item | Breast Size | Nipple Length |
|---|---|---|
| Simple adjectives | Work (huge, large) | Don’t work |
| Stacking | Works (additively gets larger) | Doesn’t work |
Weighting :1.5 | Unknown effect | Backfires |
| Specific description | oversized is strongest | cylindrical ... protruding from areola is the only one |
| Room to emphasize | Yes (more words = bigger) | None (changing anything breaks it) |
Breast size allows continuous scale control, but nipple protrusion is not a feature that can be continuously controlled, as confirmed by experimental results.
Lab Director Comment
So the conclusion from this one is basically “handle with care.” small cylindrical nipples protruding from areola only works in that exact form — change even 1 word or add weight and it breaks. This is completely different behavior from the continuous control of breast size. Just copy-paste those 6 words — that’s the move.
Practical Recommendation
If you want protruding nipples in z-image-turbo:
Do not try to emphasize it further. Don’t change to huge. Don’t add :1.5. These exact 6 words are most effective.
There are limits, though. The difference from control is “mild to moderate protrusion” — extreme nipple length is difficult to achieve in z-image-turbo.
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