Little help with Nozzle check?

[Grandad35]

The reason that I asked for a 1000 ppi scan of the small black rectangle and the starting edge of the black nozzle check is to be able to see individual dots of ink. At this resolution, it is impossible to see this detail.

 

[Blueiced]

Sorry, this is the farthest my scanner can go. 1200dpi (probably interpolated)
Almost dot-like but not enough...either way I was wondering what your experience is telling you.
Could it be a clog? Could it be ink-flow?
Can any clog be unclogged with enough soaking?
There is no ink-residue anywhere on the outside of the printhead.

http://img515.imageshack.us/img515/5188/21243462.gif

http://img62.imageshack.us/img62/4623/43450844.gif

Thanks anyway.

 

[Grandad35]

I took your images and expanded the start of the magenta and black nozzle checks, as well as adjusted the tone curves and applied some sharpening:

Note:
1. The left edge of the Magenta is straight, while the left edge of the black is jagged.
2. The Magenta has the dots fairly well distributed to give a uniform color, while the black has the dots clustered in uniformly spaced groups that are far from pleasing to the eye.

The black dots all appear to be there, so this doesn't look like a clog. It looks like the dots aren't firing straight out of the nozzles, but are being deflected at a different angle for each dot, causing this type of pattern.

The Japanese have a term for buildup inside the nozzles that can cause this type of problem - kogation. It's possible that your black ink has caused these types of deposits inside of the nozzles. Generally, it is recommended to soak the bottom (and just the bottom) of the print head on a paper towel that has been dampened (but not soaked) with "Old formula Windex with ammonia", as the ammonia seems to help break up these types of deposits.

Of course, a new print head should also cure the problem. But giving up on something that might be fixed wouldn't be in the spirit of us refillers, would it?

 

[Grandad35]

I just scanned my black nozzle check on my i9900 at 9600 ppi:

This image represents a 1/16" square (about 1.5 mm), and shows how the dots are uniformly distributed. There are a few "doublets" where the drop apparently broke up before hitting the paper, but this is how the nozzle check should look when blown up - with perfectly straight edges.

 

[Blueiced]

Wow, thanks for your effort Grandad. I haven't heard about kogation (and I tend to read here a lot).
Will take a closer look and try some soaking and Windex with ammonia? But isn't ammonia corrosive - even in small amounts?

 

[Grandad35]

..... But isn't ammonia corrosive - even in small amounts?

It's true that ammonia is corrosive, but Windex is only supposed to contain somewhere around 0.05% of a 28% solution of ammonia. At that level, it's not very corrosive. In addition, the nozzles are fabricated from ceramic, so they are fairly resistant to its effects. There are other mixtures used to clean ink residue, but it seems that ammonia is the best at breaking loose stubborn buildups.