How can I tell photo black from pigment black in

[MP640]

I won't elaborate on how this happened (too embarrassing) but I ended up with two identical unlabeled plastic bottles. One with dye photoblack ink and one with pigmented black ink. Is there a way I can tell which is which?

 

[jtoolman]

You can smear some of each with a brush or Q-Tip on a piece of Photo Paper let it dry and run it under water. The dye one should smear and run. The Pigment should be a lot more durable.

 

[stratman]

There are several ways to tell the difference. One way is to smear or paint a thin layer on plain paper, let it dry thoroughly, and then run tap water over it. The dye-based ink will run quickly because it is miscible in water. Pigment ink will not run as easily. Another way is to take a dye-based ink such as Yellow and form a tiny puddle with it. Then drop a drop or two of the black ink on top in the center of the puddle of the Yellow ink. The appearance will be similar to an egg with the Yellow being the whites and the Black being the yolk. Dye-based ink will begin to dissolve while the pigment black will hold its circular shape.

 

[The Hat]

You can smear some of each with a brush or Q-Tip on a piece of Photo Paper let it dry and run it under water. The dye one should smear and run. The Pigment should be a lot more durable.

Me thinks you got that the wrong way round especially if you are talking about photo paper..

 

[jtoolman]

Well I've acidentally,,, OK on purpose, soaked a print done with dye and pigment based on Glossy Photo paper and was able to tell. The dye one ran and pigment one did not. I suppose regular bond paper would work for the test. But then it's just a guess.

 

[Harvey]

Well I've acidentally,,, OK on purpose, soaked a print done with dye and pigment based on Glossy Photo paper and was able to tell. The dye one ran and pigment one did not. I suppose regular bond paper would work for the test. But then it's just a guess.

The best paper to do the test is bond paper, or it could be toilet paper or towel paper that I consider to be even better.

 

[MP640]

I did the test on photo paper, but there was no difference in smear. Isn't that how it should be with photo paper, anyway?

 

[The Hat]

If you use photo glossy paper with dye ink it will not wash off it is in fact water proof.
But if you use your pigment black on the same paper it will wash off.

If your dye ink washes off the photo paper then you need to find yourself a better ink supplier.
On the subject of using bond paper with dye ink its totally useless, bleaching (feathering) is uncontrollable with this type of old paper,
I would recommend the use of copier paper as it's far better for everyday colour use..

 

[gigigogu]

MP640

Drip few drops on a sink then pour water over.
Pigment ink should disperse as a pure gray mist and it should leave a gray spot on sink, removable only by scrubbing.
Dye ink should disperse as a colored liquid, deep blue or deep indigo, depending on ink. It should dissolve completely without leaving a spot on sink (or barely visible)
Alternative: Drip few drops on a sink, let them dry, then pour water over.
Pigment ink should not dissolve at all, requiring scrubbing to clean the sink.
Dye ink should dissolve immediately, leaving only a faint mark.

 

[PeterBJ]

I read somewhere that pigment ink must be alkaline for the pigments to stay dispersed. In an acidic solution pigments will precipitate. I did a quick test by adding 1 ml of pigment ink to 50 ml of acetic acid 32% in a 100 ml plastic bottle. The acetic acid used was common household grade used for de-liming coffee-makers etc. I did the same test with 1 ml of dye ink to 50 ml of acetic acid. The pigment ink precipitates and the dye ink dissolves in the acid. I did the same test with household vinegar with 5% of acetic acid and pigment ink. If enough ink was added, the ink started to dissolve in the vinegar, therefore the use of 32% acetic acid for the test. I think dye ink is acidic and that this is the basis of the "HP egg-yolk test".

Here is a scan of the two bottles with the pigment ink at right.