Do I have a problem with dry sponges

[leo8088]

Wick is a weaker word but not much different from the word pull. If you fill up a coke bottle with water. Flip over (upside down) and put the mouth of the bottle in a cup of water. You will see how atmosphere pressure keeps the water in the bottle from flowing out. Only when you begin to drink the water in the cup and allows air to enter the bottle the water in the bottle will then flows out. The amount it flows out will be equal to the volume of air entering the bottle.

The sponge contains ink. When the ink is consumed it will wick any ink that the sponge can reach. But the wicking force is never greater than the atmosphere pressure against it. When the ink in the sponge is consumed and its ink level lowers to a point that allows air to reach the slit at the tank ink will then exchange with air and allows ink to flow out. Before air reaches the slit the print head will draw ink out of the sponge only. There is nothing but capillarity holding the ink. It is easily overcome by the drawing force from the print head. This is the part that people can't see clearly how it works. Mikling's post showed that he did not have a clear understanding of it.

You can easily observe this. When a new cartridge is installed the ink level in the tank will not lower for many days. It gives you a false feeling that the ink consumption is low. This is because ink is consumed out of the sponge only in the first few days. The sponge does not pull ink out of the tank to replenish the sponge. When the ink level in the sponge is so low that allow air to reach the slit then the ink begins to flow out to be consumed by the print head. If the sponge does pull ink out of the tank why it does not saturate the top of the sponge? If you top fill the cartridge you can see the sponge pulls the ink from the tank and saturates the top if you don't plug up the fill hole sooner. Once it is plugged ink can not be pulled by the sponge any more. The top of the sponge remains unsaturated forever that way. This proves that ink is not pulled or wicked out from the tank by the sponge.

It was the reason Mikling criticized the German engineering. He misunderstood how the cartridge works. Although he denied his criticism he did criticize it.

 

[mikling]

Thrilla the sponge was dried off with a paper towel and then reinserted.

I was showing that it is possible to have a condition that you have a full tank and no ink comes out.
We know that happens on some third party cartridges sometimes. Is this the cause of it? I don't know but it is a possibility.

Leo8088, the groove I am referring to does not exist in the BCI-6. You are looking at the grooves on the separation wall. The groove I am referring to is known to folks who have filled the CLI-8 and newer carts. You are not looking at a CLI-8. Go get one and compare the construction and then assess the situation.

THE END.

 

[ThrillaMozilla]

It's a small point, I was going to say, I suspect the colored water doesn't come out because the sponge is already saturated with water, and I'll be it would drain. But you could also have an air bubble in the opening between chambers, which of course is the point of most of this. If it doesn't already flow, you could probably just tap it to get the bubble out.

I have to say, though, you have gotten it virtually 100% correct. It's a shame that not everyone undestands that. For anyone who wants to see an authoritative source on how the sponge-and-chamber system works, you can read the Canon U.S. patent here, if you have sufficient patience and sufficient understanding of science: http://www.google.com/patents?id=uhcbAAAAEBAJ&pg=PA1&dq=Canon patent 5509140 sponge&hl=en&ei=YIwtTpmbEoLosQLvv9C_Cw&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCgQ6AEwAA#v=onepage&q=Canon patent 5509140 sponge&f=false . The patent corroborates every point Mikling has made, except that there's no mention of the air lock that Mikling noticed.


COMMENT ADDED Feb. 2015:
I have actually observed the air lock that mikling mentioned, so it's not just theoretical. I had a cartridge quit feeding even though the ink chamber was almost full. I removed the cartridge, held it with the ink chamber up, and tapped it lightly to release a bubble from between the chambers. A stream of bubbles immediately started flowing into the ink chamber. I then held the cartridge in the usual orientation (vent side up, outlet side down), and the bubbles continued until a few milliliters had flowed into the sponge. The cartridge then worked normally. If you do a little searching, I posted a radiograph of an opaque cartridge in which a bubble is clearly visible between chambers. Since then, I always try to remember to give my cartridges a little tap before installing them. (These are HP cartridges that are constructed like the Canon cartridges.)

I've mentioned this elsewhere, but I thought I should add this comment close to Mikling's original description.

 

[ThrillaMozilla]

There's one point that hasn't been made, and this is directly applicable to the original problem. The Canon patent notes that a new, dry sponge soaks up ink poorly. (It soaks up ink to a height of just a few millimeters. I don't know whether it's just slow or whether it really will not soak up much ink.)

But there's a reason the upper sponge may need to soak up ink. Does anyone know why the grooves do not extend upward all the way to the top of the cartridge? It's to keep the cartridge from leaking in case of a large change in atmospheric temperature or pressure. Any ink that is forced out of the ink chamber can be absorbed by the sponge. (See Canon patent, Embodiment 5.) I don't know for sure whether the dry upper sponge could pose a problem, but it looks to me like in some of those cartridges it's acting more like a barrier than a sponge.

 

[mikling]

The pressure change issue and the upper sponge is a perfectly valid reason for its existence. It makes perfect sense, for the same reason why I mentioned constant pressure CISS systems have this same issue in their dip tubes. I had overlooked this. This is an excellent point.

From the quick look of the patent, it is dated 1994-6?, the CLI-8 groove was introduced about ten years later and its evolutionary design changes addressed things they saw in practice which possibly pointed to a greater need of a stronger interface bond between sponge and tank in certain situations.

BTW thanks for the patent link and I honestly never read it before but I just used my wits and experimentation to figure it out.

 

[inkadinkado]

Mikling:

I'm really enjoying my little orange clips that I recently purchased from your Ebay store.
And, I refill by the method you described and it works just great. Knock on wood, no over saturated sponges, no leaks, no cart problems and I wouldn't dream of using anything but OEM carts to refill. Just too risky.

The one thing I haven't done is put tape over the vent hole on stored carts. I've had no leak problems or usage issues by not doing this. If I might ask, what is your reason for recommending it?

I look for your posts. So informative.

 

[rodbam]

I think Mike recommends putting tape over the vent holes to stop ink getting up there when you refill as it creates a bit of pressure build up. I don't think you need tape over the vents for storage.

 

[inkadinkado]

rodbam

I believe Mikling IS speaking of storage carts here, no?
"If your workflow includes a second set of cartridges then having the tape over the vent holes might actually be a bonus in that it can't hurt during storage."

I have not included tape over the vent hole on my storage carts and my question was...."why do we need to do this?"

 

[ghwellsjr]

Actually it can hurt to leave a seal over the air vent hole. The daily fluctuation of ambient air pressure will force air in and out of your cartridge. The air vent hole is there to safely let the cartridge "breathe". If you plug up this passage, the cartridge will breathe through another hole, most likely, the outlet port. That can cause ink leaking out the port and/or ink drying out inside the sponge.

So I recommend leaving tape off the air vent hole.

 

[ThrillaMozilla]

Actually it can hurt to leave a seal over the air vent hole. The daily fluctuation of ambient air pressure will force air in and out of your cartridge. The air vent hole is there to safely let the cartridge "breathe". If you plug up this passage, the cartridge will breathe through another hole, most likely, the outlet port. That can cause ink leaking out the port and/or ink drying out inside the sponge.

Then why do the manufacturers seal the vent?