# OPUS 88 Harmony Fountain Pen - Mocha Mousse

## A soft café toned demonstrator with warmth 

The Opus 88 Harmony Mocha Mousse is a full sized eyedropper fountain pen finished in a muted coffee-inspired resin with soft purple translucency and layered depth. It blends warm neutral tones with Opus 88’s high capacity writing system, creating a pen that feels calm and effortlessly usable.

## What sets it apart

-   High capacity eyedropper filling system for extended writing
-   Shut-off valve prevents leaks
-   Soft mocha mousse resin with warm, neutral translucency  
    
-   Comfortable full size design suited to long writing sessions
-   Size #6 Jowo nib unit for easy nib swaps

### Feel in the hand

The Mocha Mousse feels warm and elegant. Its neutral coffee tone creates a relaxed writing environment that doesn’t compete for attention, making it easy to settle into your writing.

### Who it’s for

-   Writers who prefer neutral colour palettes
-   Ink users who value high capacity pens for long sessions
-   People who like understated demonstrators with muted tones
-   Journaling, planning, and daily writing users
-   Nib explorers who enjoy swapping out nibs

### Not for

-   Users who prefer bright or highly saturated colours
-   Those who want compact or pocket-sized pens
-   Writers looking for bold, high contrast design statements
-   Anyone who prefers opaque metal or heavily decorative finishes

### Practical tips

-   Keep the shut-off valve slightly open during writing
-   Close the valve before transport to prevent leakage  
    
-   Try different #6 nib styles to fine-tune writing feel

### FAQs

**Is the Mocha Mousse fully transparent?**  
It is translucent, allowing ink visibility while diffusing it through a warm coffee tone

**Does it use cartridges or converters?**  
No, it uses an eyedropper filling system with a shut-off valve

**Do I need to add silicone grease on the grip threads to prevent leaks?  
**No, the design includes a thick o-ring already.

**Is it suitable for beginners?**  
Yes, though it benefits from basic understanding of eyedropper pens

**Can it handle document and shimmer inks?**  
Yes, with regular cleaning recommended

**What nib does it use?**  
Standard #6 JoWo-compatible steel nib

**What other nibs is it compatible with?**  
Other size #12 JoWo nib units and also the nib unit from the Pilot Parallel art pen

### What’s included

-   Opus 88 Harmony Mocha Mousse Fountain Pen
-   Eyedropper 
-   Spare small o-ring for back of grip section
-   Instruction leaflet
-   [Free nib tuning](https://www.larrypost.com.au/blogs/blogs/smooth-writing-with-fountain-pens?_pos=2&_sid=a2392eaaf&_ss=r) by LarryPOST

### Ink pairing suggestions

-   Sepia inks for cohesive café tones  
    
-   Teal inks for balanced complementary contrast
-   Deep blue inks for clean everyday writing

### Build your practice

-   [Pilot Iroshizuku](https://www.larrypost.com.au/collections/larrypost-brands-pilot-pen?filter.p.m.magento.brand_series=PILOT+Iroshizuku) inks for intensity and volume
-   [Herbin](https://www.larrypost.com.au/collections/larrypost-brands-herbin) inks for colour range
-   [Midori](https://www.larrypost.com.au/collections/larrypost-brands-midori) notebooks with cream paper for calm feel

### Specifications

-   **Brand:** Opus 88
-   **Brand series:** Harmony 
-   **Launch:** 2024
-   **Origin:** Taiwan
-   **Nib:** Jowo #6, rose plated stainless steel
-   **Nib sizes:** EF, F, M, B, 1.5mm stub
-   **Filling system:** Eye dropper
-   **Material:** Translucent acrylic
-   **Trim:** Rose-gold coloured
-   **Weight:** approx. 25g (capped)
-   **Length:** approx. 146mm
-   **Diametre:** approx. 15mm
-   **Comparable size:** Twsbi Diamond 580

  

Pretty and dependable, inspiring you to start and continue.

## Details

- **Price:** 235.0 AUD
- **Vendor:** OPUS 88
- **Type:** Fountain Pen
- **Tags:** Category_LarryPOST, Category_LarryPOST/Brands/OPUS 88, Category_LarryPOST/Brands/OPUS 88/OPUS 88 Harmony, Category_LarryPOST/New, Category_LarryPOST/New Products, Category_LarryPOST/Pens, Category_LarryPOST/Pens/Fountain Pen, New Fountain Pen

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Fine | 235.00 AUD | In stock |
| Medium | 235.00 AUD | In stock |
| Broad | 235.00 AUD | In stock |

## Images

- OPUS 88 Harmony Fountain Pen - Mocha Mousse
- OPUS 88 Harmony Fountain Pen - Mocha Mousse

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> Source: [LarryPOST](https://www.larrypost.com.au/products/opus-88-harmony-fountain-pen-mocha-mousse-fine-nib)
> Updated: 2026-08-29