Compiled from 14 sources; we haven't tested this product ourselves yet. How we research
Quick answer
Platinum Classic Ink (INKK-2000) is six 60 ml (2.0 fl oz) fountain pen inks from Platinum of Japan: Cassis, Forest, Citrus, Khaki, Sepia and Lavender Black. Platinum says each starts as a bright color and turns black as the iron in it oxidizes. Mountain of Ink saw only slight feathering on copy paper.
Water-based dye ink, acidic, containing iron, in a glass bottle with an ink reservoir
Price range
$$$$20–75 per item
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Notes on these facts
Made by Platinum Pen Co., Ltd. (Tokyo). Made in Japan: Mountain of Ink's Platinum index page says Platinum ink is made in Japan. Platinum's Japanese product page for INKK-2000 (read on October 30, 2026) doesn't state a country. Source. Price: example listing.
Price bands are typical US retail, checked October 2026. Conversions to US dollars are approximate, at October 2026 rates (US$1 = ¥158 = ₩1,330 = NT$32.5 = CN¥6.7 = SEK 9.9 = DKK 6.7 = ₺49.6 = C$1.41 = A$1.43 = CZK 21.7; €1 = US$1.12; £1 = US$1.32; CHF 1 = US$1.21).
Key takeaways
Platinum's Japanese brand page lists six shades, all sold as one 60 ml bottle, INKK-2000: #15 Cassis Black, #44 Forest Black, #47 Citrus Black, #61 Khaki Black, #66 Sepia Black and #86 Lavender Black.
Platinum describes a traditional blue-black recipe in which iron oxidizes and writing darkens toward black; its spec line still calls the ink water-based and acidic.
Mountain of Ink timed the six shades at 30 to 50 seconds to dry on fountain pen paper.
Mountain of Ink saw no feathering and no bleed on fountain pen paper, and only a little feathering on Staples 24 lb copy paper; the two brown shades bled slightly with a flex nib.
Platinum's care page asks owners to soak the nib section in lukewarm water about once a month; it gives no Classic-specific rule.
What is Platinum Classic Ink?
It’s a line of six fountain pen inks from Platinum, the Tokyo pen maker, designed to start in a color and darken toward black as the writing ages. Platinum’s Japanese brand page lists them as Classic Ink, code INKK-2000, one 60 ml bottle per shade.
The shades are #15 Cassis Black, #44 Forest Black, #47 Citrus Black, #61 Khaki Black, #66 Sepia Black and #86 Lavender Black. Platinum’s page writes the names in katakana; the romanizations here match Goulet’s and Yoseka’s listings. Platinum’s brand page lists only the bottle, so we found no Classic cartridge.
Platinum Classic Ink specs
Spec
Value
Maker
Platinum Pen Co., Ltd., Tokyo
Code
INKK-2000 (item codes 4299015, 4299044, 4299047, 4299061, 4299066, 4299086, in the order above)
Bottle
60 ml (2.0 fl oz), glass, ink reservoir included
Bottle size and weight
W57 x 57 x H63 mm (2.2 x 2.2 x 2.5 in), 180 g (Platinum Japan)
Ink type
Water-based dye ink, acidic (Platinum Japan spec line); iron-containing, called iron gall by Goulet
Japan list price
¥3,300 (about US$21) with tax
Dry time
30 to 50 s on fountain pen paper, by shade (Mountain of Ink)
Shading / sheen
High / none (Mountain of Ink)
Price band
$$$ ($20-75 per bottle)
Made in
Japan (Mountain of Ink)
Fills per bottle (bottle volume ÷ filler capacity, rounded down):
Filler
Holds
Fills per 60 ml bottle
Pilot CON-40 converter
0.4 ml
about 150
LAMY Z28 converter
0.8 ml
about 75
TWSBI ECO piston
1.76 ml
about 34
How is Classic Ink different from dye and pigment ink?
It aims to be a dye ink on day one and a dark, fixed mark later. Platinum’s ink notes sort inks into types: an alkaline dye ink washes out with water and browns in sun; a carbon pigment ink never redissolves once dry; and a blue-black ink works by iron.
For the iron type, Platinum explains that ferrous iron oxidizes to ferric iron and forms a black deposit. Dye and acid are added so it writes easily, and the dye fades, leaving the black. Platinum says it is the only Japanese company still making this traditional blue-black, and its brand page says Classic Ink was developed around that darkening. Our Carbon Black guide covers Platinum’s pigment ink, and our ink properties explainer covers the general terms.
Is it an iron gall ink? The sources disagree
Retailers say yes; Platinum’s own spec line says dye. Goulet’s pages for Citrus Black, Forest Black and Lavender Black call them iron gall inks, and Mountain of Ink calls the line six iron gall inks. Platinum’s Japanese spec line reads water-based dye ink (acidic), while its text describes the iron-oxidizing process without using the word gall.
We couldn’t find Platinum’s formula, so the safest reading is an acidic ink with iron that darkens as it oxidizes. Goulet adds that the color darkens within the first 24 hours, and may change visibly after an hour.
How do the six shades behave?
All six dry in 30 to 50 seconds and shade strongly; they differ in water resistance and in how much they change. Mountain of Ink reviewed them in September 2017 and October 2018, so a bottle bought today may differ.
Shade
Mountain of Ink’s color note
Dry time
Water resistance
Cassis Black
Bright pink-red wet, dark unsaturated red dry
30 s
Low
Forest Black
Unsaturated medium green
40 s
Medium
Citrus Black
Dark yellow with a green undertone
40 s
Low
Khaki Black
Medium warm brown, little change seen
30 s
Low
Sepia Black
Cool-toned brown, little change seen
50 s
Low
Lavender Black
Medium pink wet, medium purple dry
45 s
Medium
Platinum calls the ink water resistant, yet the reviewer expected much more resistance than the test showed, which we can’t reconcile; the timing of the water test isn’t stated. We show no swatch tints because no source measured them.
How does it behave on ordinary paper?
Better than most dye inks, with only slight feathering on copy paper. On Rhodia, Tomoe River and Leuchtturm, Mountain of Ink saw no feathering, medium show-through and no bleeding for the six shades.
On Staples 24 lb copy paper, Cassis, Citrus and Forest Black feathered a little with no bleed; for Forest Black it was not noticeable until the broad nib. Khaki Black showed a tiny bit of bleed and Sepia Black some bleed with a flex nib. Lavender Black’s review doesn’t mention copy paper.
The reviewer described a dry flow with these inks, so a wetter pen may behave differently.
How should you look after a pen filled with it?
Flush the pen on a schedule and don’t leave the ink sitting in it. Platinum’s care page says to soak the nib section in lukewarm water, rinse until the water runs clear, and do so about once a month, and also when changing ink. Platinum sells a cleaner kit (ICL-1200) for heavy soiling.
That page is general, not specific to Classic Ink.
The “don’t leave it too long” advice comes from Mountain of Ink’s Lavender Black review, which also warns that the plastic ink reservoir in the bottle jammed the reviewer’s pen. Platinum says its 14K, 18K and stainless nibs resist acid inks; we found no test on plated or vintage nibs. Our guide to cleaning a fountain pen covers the flush, and the Platinum Preppy and #3776 Century are Platinum pens you could try it in.
How much does it cost?
¥3,300 (about US$21) in Japan with tax, and in the $$$ band in the US. Yoseka Stationery’s pages for five of the shades and Goulet’s pages for three were all listed in that band when we checked on October 30, 2026. We found no Lavender Black on Yoseka’s site.
Where is Platinum Classic Ink made?
In Japan, according to Mountain of Ink. Platinum’s product page doesn’t state a country; the company is based in Tokyo. We found no launch date on a Platinum page.
Frequently asked questions
Is Platinum Classic Ink an iron gall ink?
Sources disagree on the label. Goulet and Mountain of Ink call it iron gall; Platinum's Japanese spec line says water-based dye ink, acidic, while its text describes a traditional recipe in which the iron in the ink oxidizes and turns the writing black.
Which colors does Platinum Classic Ink come in?
Six, as Platinum's Japanese brand page lists them: #15 Cassis Black, #44 Forest Black, #47 Citrus Black, #61 Khaki Black, #66 Sepia Black and #86 Lavender Black. All are one 60 ml bottle.
Does Platinum Classic Ink turn black?
That is the design: Platinum says the writing starts as a bright dye color and darkens over time. Goulet says the color darkens within the first 24 hours; Mountain of Ink found little change with Khaki Black and Sepia Black.
Is Platinum Classic Ink waterproof?
Platinum calls the ink water resistant and suited to long-term records, but Mountain of Ink rated four of the six low and Forest Black and Lavender Black medium, so test before relying on it.
Does Platinum Classic Ink work on copy paper?
Reasonably. Mountain of Ink saw only a little feathering on Staples 24 lb copy paper with Cassis, Citrus and Forest Black, and slight bleed with a flex nib for Khaki and Sepia. Lavender Black was not tested on it.
How do you clean Platinum Classic Ink out of a pen?
Platinum's care page says to soak the nib section in lukewarm water, rinse until the water runs clear, and do this about monthly and before changing ink. A reviewer adds not to leave the ink in a pen for too long.
Does Platinum Classic Ink damage fountain pens?
Platinum says its gold (14K and 18K) and stainless steel nibs resist acid inks without rusting or corroding. It gives no pH figure or warning for Classic Ink, and we found no test of the inks on other pens.
How big is a bottle of Platinum Classic Ink?
60 ml (2.0 fl oz). Platinum's Japanese site lists W57 x 57 x H63 mm and 180 g, with an ink reservoir included.
