BCI-6 / BCI-3 Mysteries??

[turbguy]

When I look at a new or a spent OEM BCI-6 cart, invariably there is a portion of the "sponge" at the top that is not stained with ink. I refill by the "top method" and invariably that top portion fills with ink (probably 90+% of the time).

This doesn't seem to disturb the print-outs, but does anybody knom if this "full sponge after refill" issue is significant? It occurs if I tape over the sponge compartment vent during refill, or if I don't.

How does Canon prevent "full saturation"? Any ideas or comments??

Wayne

 

[pharmacist]

Normally it upper area should stay clean or only partially soaked in ink. If not, the sponge is oversaturated, which is not beneficial for printing (can cause banding, you fortunately you do not seem to suffer from this). If you refill by the top method you should squeeze the sponge area till 5-10 drops have been removed from the cartridge to ensure optimal saturation.

I suggest you to try the german durchstich refill method, which will automatically gives the optimal saturation degree in the sponge. This is by far the easiest and best refill method and you do not need to seal the ink outlet (top method will cause dripping) and it will also prevent from oversaturating the upper sponge material.

 

[turbguy]

I religiously squeeze out 5-6 drops from the outlet port after every refill. Perhaps that's why I don't get "banding"? In any event, why doesn't the sponge "wick" ink to the top during OEM fills via capillary action?

Waynre

 

[ghwellsjr]

The "sponge" in Canon's cartridges is actually two sponges, the bottom one is designed to allow the easy flow of ink and the upper one is designed to allow the easy flow of air and to repel ink. I have no idea how Canon actually fills their cartridges but if you take a cleaned and dried cartridge and refill the reservoir with the German method and then let it sit right-side-up for a view minutes, about half of the ink in the reservoir will seep out and saturate the bottom sponge leaving the upper sponge completely dry. Even if you refill the reservoir again, no ink will flow into the upper sponge material.

If you look closely at the wall separating the two chambers, you will see groves on the sponge side of the wall that go up from the hole in the bottom of the wall half way up and stop just below the top of the bottom sponge. As ink is drawn out of the reservoir, air must go from the air vent on the top of the cartridge, through the upper sponge material, along the groves and into the hole in the bottom of the wall to replace the ink that comes out of the reservoir. Without this free air path, the cartridge will be unable to provide ink to the print head, once it is drained from the sponge materials.

When Canon first came out with this particular type of cartridge, the BCI-3 series (without the "e"), it had a single large sponge. Apparently, this led to ink flow problems and Canon changed to the two-sponge design and called the cartridge BCI-3e. You can still buy these cartridges for dye ink colors as well as the wider pigment black. Most, if not all, compatible cartridges use only a single sponge material which is why I do not recommend them for refilling.

I used to vacuum fill my cartridges in a way that completely saturated both sponge materials. I never had any problem with ink flow on the first refill. However, subsequent refills did have problems and I believe it was because the dried ink in the upper sponge material offered too much resistance to the free flow of air. I now refill with the German method soon after the reservoir is empty.

 

[turbguy]

I can see an obvious dividing line in the sponge chambers`as if there are two types of "sponge".

When you refill via the "German Method", the top sponge doesn't saturate?

Wayne

 

[ghwellsjr]

That's correct, as long as you inject the ink only into the reservoir. Sometimes, if you refill while the bottom sponge is still saturated, the air leaving the reservoir can force some of the ink from the bottom sponge into the top sponge but it won't flow up from the bottom sponge into the top sponge when you're done and have turned the cartridge right side up.

 

[turbguy]

It appears we are dealing with pressures at the printhead equal to fractional inches of water head, just enough to keep the nozzles primed, but not enough to overcome "surface tension" of the ink in the nozzles and cause leakage.

Makes me wonder why the top sponge is there at all!

 

[ghwellsjr]

Makes me wonder why the groves don't go up all the way so that it would work correctly with a single larger sponge but maybe there is some technical reason why they don't do it that way.

I've read that the latest version of Canon cartridges are actually not as tall. Maybe they accomplished the same thing (a single sponge material) while gypping the customer with a smaller ink reservoir.