Sailor Studio Ink Bottle (640 Blue - 20ML) 13-1210-640

Sailor Studio Ink Bottle (640 Blue - 20ML) 13-1210-640

Product Overview

The Sailor Ink Studio 640 Blue is one of over 100 distinctive ink colors in Sailor’s Ink Studio collection, a carefully curated series of dye?based inks developed from Sailor’s long experience in ink mixing and feedback from pen enthusiasts. Sailor Pen+2The Goulet Pen Company+2 This 20?mL glass bottle offers a premium presentation combined with day?to?day usability — ideal for writing, journaling, sketching, or adding expressive color to your pen rotation. The Goulet Pen Company+1

The square bottle design (34 × 34 × 58 mm) is complemented by a paperboard outer box and a set of small stickers/labels to mark your converter or pen with the ink name, helping you keep track when using multiple inks. Sailor Pen+2andersonpens.com+2

Color & Visual Character

Color #640 is generally described as a blue / blue?black hue — a medium shade leaning toward a subtle grey?blue tone, rather than a vibrant or electric blue. Mountain of Ink+4andersonpens.com+4The Goulet Pen Company+4 In swatch and chromatography tests, 640 shows interesting behavior: the edges (when diluted or spread with water) often bleed into greys or turquoise hues, producing soft gradients and a delicate, layered appearance. FOUNTAIN PEN INK ART+2Mountain of Ink+2

Unlike inks with heavy sheen or shimmer, 640 is reported to be free of glitter or metallic particles. The Goulet Pen Company+1 In certain tests, it displays medium shading and some mild sheen depending on paper and wetness, though this is subtle and not dominant. Mountain of Ink+2Fountain Pen Pharmacist+2

Some ink?review sources note a grey undertone under certain lighting or on specific paper, lending 640 a somewhat muted or “gentle” appearance rather than a strongly saturated blue. Mountain of Ink+1

Technical Specs & Behavior

• Type: Water?based dye ink (non?pigmented) Sailor Pen+2The Goulet Pen Company+2

• Volume: 20?mL per bottle The Goulet Pen Company+1

• Bottle dimensions: ~?34 × 34 × 58 mm (glass) Sailor Pen+1

• Weight (filled): ~?94?g (gross) Sailor Pen

• Packaging: Paperboard outer box (~37.5 × 37.5 × 61 mm) Sailor Pen+1

• Included accessories: A set of small stickers / converter labels to help you mark the ink in your pen andersonpens.com+1

Performance & Use Behavior

• Flow / Wetness: The ink generally flows smoothly and steadily, offering reliable performance across a variety of pens. Fountain Pen Pharmacist+3andersonpens.com+3The Goulet Pen Company+3

• Drying Time: In tests, drying times vary depending on paper and nib, but on good fountain?pen friendly paper it tends to take moderate time (not ultra fast). For example, in one review grouping 640 with related blues, drying was reported around 40 seconds under some conditions. Mountain of Ink+1

• Shading / Variation: Moderate shading is possible under wetter applications or with flexible/broad nibs, though the effect is more subtle compared to highly shading inks. Mountain of Ink+2Fountain Pen Pharmacist+2

• Bleed / Feather / Show?through: On fountain?pen friendly paper, feathering is minimal. But on more absorbent or lower-grade paper, some feathering or bleed may occur, especially in broader or wetter nibs. Show?through is described as moderate in tests. Mountain of Ink+1

• Water Resistance: Low. The ink is not water resistant and can wash or blur under exposure to water. Mountain of Ink+1

• Chromatography / Edge Effects: In watercolor or watery spread tests, the ink often splits into greys, turquoise, or bluish trailing edges, giving a soft diffusion visual effect. FOUNTAIN PEN INK ART+1

• Stability & Safety: Being a dye ink, 640 is intended to be safe for use in fountain pens and relatively easy to flush; regular cleaning is recommended to maintain pen health. andersonpens.com+2The Goulet Pen Company+2

Use Cases & Appeal

• Ideal for writers or artists seeking a mature, calm blue that isn’t overly bright or saturated, but still carries personality and depth.

• Suitable for daily writing, journaling, correspondence, or light sketching — especially when you want more character than a standard “navy” but less flamboyance than high-shimmer inks.

• Because of its moderate nature, it pairs well with a range of paper types and nibs, from fine to broader, without overwhelming contrast.

• The 20?mL size encourages experimentation or rotation, and the included converter labels ease ink management across multiple pens.

• For those who like subtle visual interest, 640 can reveal gentle gradients or edge effects under wetter strokes, especially on absorbent or textured papers.

Sample / Comparisons & User Impressions

• In the “Ink Studio Set 11” review, 640 was grouped with blue?family inks. The reviewer noted that 640, 740, 840, 940 all showed medium sheen and medium shading in certain papers, and 640 had a “bit of a grey undertone.” Mountain of Ink

• In swatch test series “The Blues,” 640 is described as “a delicate deep grey blue that blends easily with water and bleeds out greys and turquoise at the edges,” with no sheen visible under those conditions. 

• In listing descriptions, Anderson Pens refers to it as a “medium shade of blue?black” in the Ink Studio series, and emphasizes the smooth performance, good flow, and ease of rinsing from pens. 

• Some reviewers on fountain pen blogs include 640 among the “blue group” and test it on Tomoe River and other fine papers, noting that its character shifts with paper type — with darker, more saturated look on heavier paper, and more muted/greyed tone on thin, crisp paper. 

• One community user compared it to other blues and described it as “nice and wet but not too much” with “lovely saturation,” though perhaps slightly lighter than their personal preference.