TWSBI Fountain Pen VAC Mini

The TWSBI VAC Mini is a compact vacuum filler in demonstrator design: The completely transparent barrel lets the piston mechanism and ink level remain visible at all times. The broad nib with 1.1 mm slit width creates a characteristic contrast between horizontal and downstrokes – precise enough for calligraphic scripts, smooth enough for extended writing sessions. Filling is done via a single-stroke vacuum mechanism that draws up nearly 2 ml of ink in one motion.

Special Features

• Vacuum Filling System: A single stroke – pull the piston, dip the nib, push the piston down – fills the barrel with up to approximately 2 ml of ink. This corresponds to almost double the capacity compared to a standard converter.
• Ink Shut-off Valve: The rear closure screw seals the ink flow completely. During transport, in a bag, or aboard, the ink remains safely in the reservoir without reaching the nib.
• Demonstrator Barrel: The faceted barrel made from clear acrylic resin shows ink level and piston rod in real time. Inks with sheening or shimmer properties develop special effects in the transparent corpus.
• Broad Nib Steel No. 5, 1.1 mm: German-made stainless steel nib with 1.1 mm slit width. The flattened nib back creates broad downstrokes and thin crossstrokes – typical for italic handwriting and lettering. The flow is generous with slightly perceptible feedback on the paper surface.
• Screw Cap with Posting Function: The faceted cap can be screwed onto the back of the barrel with 1.5 turns – even when the ink shut-off valve is open. Posted, the pen achieves 151.7 mm for balanced comfort for hands of any size.
• Interchangeable Nib Unit: The nib unit can be changed by unscrewing the grip section, without tools. Compatible replacement nibs in No. 5 format are available separately.
• Maintenance Kit Included: TWSBI includes a wrench, replacement O-rings, and silicone grease – for complete disassembly, cleaning, and reassembly of the filler.

Application & Tips

• Open Ink Shut-off Valve Before Writing: For longer writing sessions, the rear shut-off valve must be unscrewed so that ink can flow to the nib. For brief signing or notes, it can remain closed.
• Optimal Filling: With a TWSBI VAC20A ink bottle, the barrel can be filled to maximum capacity. With standard ink bottles, the pen fills to approximately two-thirds of maximum volume.
• Broad Nib and Paper: On smooth, ink-resistant paper, the 1.1 mm broad nib shows the strongest contrast between upstroke and downstroke. Rough or highly absorbent paper can fray the stroke edges and weaken the line variation.
• Ink Selection: The generous capacity and wet flow of the broad nib work well with water-based fountain pen ink of any kind – from classic iron gall inks to heavily sheening shimmer inks that require careful cleaning after use. Pigmented inks are possible but require regular flushing of the vacuum mechanism.
• Posting for Large Hands: Unposted, the pen measures 114.5 mm – for extended sessions, screwing the cap onto the back end to a total length of 151.7 mm is recommended.
• Cleaning: The included wrench allows complete disassembly for thorough flushing. Tighten the grip section before first filling to prevent leaks.

For Calligraphy Enthusiasts

The 1.1 mm broad nib of the VAC Mini is a German-made No. 5 nib with italic grind. Unlike a pure calligraphy nib with sharp edge geometry, the grind is slightly rounded – this creates soft transitions between stroke widths and makes the nib suitable for everyday use in fast, expressive handwriting. Those who work deliberately with stroke contrast – Copperplate variants, Italic Handwriting, Brush Lettering supplements – will appreciate the even, wet flow that remains stable even on a slightly angled pen. The vacuum seal also allows the use of intensely colored or shimmering inks without the risk of uncontrolled leakage from vibration.

Technical Specifications