Yellow discoloring for first few passes

[midnightmadman]

I'm printing a yellow logo. It has a black ring around it.
For the first 1" or so the yellow is printing discolored more like a pale greenish and then it clears up perfect for the rest of the print.
Its done it 3 times already and I cant figure out why.
Prismjet extra printer.
Any guesses!?

 

[artbot]

the cyan ink in the capping station right next to it and you are getting contamination at the head. when you pull the head aside, is there more or less yellow or cyan ink sitting in the caps? what kind of printer is it?

 

[midnightmadman]

the cyan ink in the capping station right next to it and you are getting contamination at the head. when you pull the head aside, is there more or less yellow or cyan ink sitting in the caps? what kind of printer is it?

Whats causing contamination?

Prismjet EXtra... or Mutoh

 

[artbot]

that's a tricky one. i've seen it after a printer sits too long doing a cap-soak. but your case is different. if it keeps appearing over and over, not purging and being done with it, there's only two possiblities:

1) that your cap/line is clogged a bit and holding too much ink and the cyan is whicking into the yellow.

2)is that you have some positive pressure inside of your yellow line. and instead of the ink slowly syphoning out it is instead syphoning cyan ink in.

i'd first look for a clogged yellow line (piercing nipple, bad cartridge, clogged line). ...something that would cause the vacuum in the line to be too high.

 

[midnightmadman]

that's a tricky one. i've seen it after a printer sits too long doing a cap-soak. but your case is different. if it keeps appearing over and over, not purging and being done with it, there's only two possiblities:

1) that your cap/line is clogged a bit and holding too much ink and the cyan is whicking into the yellow.

2)is that you have some positive pressure inside of your yellow line. and instead of the ink slowly syphoning out it is instead syphoning cyan ink in.

i'd first look for a clogged yellow line (piercing nipple, bad cartridge, clogged line). ...something that would cause the vacuum in the line to be too high.

Maybe different amounts of ink in the cartridges?

 

[artbot]

that's tricky. syphons only need a small amount of positive pressure inside the line to work. think of it as a train made of fluid. and it is running down hill pulling the shorter side or it's tail over a hill. if the ratio between the yellow and cyan was high at the cartridge, it might be able to steal vacuum at the cap. but i'm confusing myself even pondering it.

first do a damper swap between the yellow damper/line and the cyan damper/line. print a yellow square. it will print cyan. see if it starts out greenish and then fades cyan. and then post the results.

 

[thmooch]

post some pics of the print. There are a lot of people on here that can tell whats going on by looking at the output. Believe me, I just had trouble with my PrismJet Extra, but received very valuable input here.

 

[midnightmadman]

post some pics of the print. There are a lot of people on here that can tell whats going on by looking at the output. Believe me, I just had trouble with my PrismJet Extra, but received very valuable input here.

Thanks guys. Its strange because it clears after the first 1" or so and its perfect.
Then I starts again for the next print and does the same. I did 3 of them

As far as pulling off the damper and switching, is that safe to do? wont the inks get really mixed up inside?
One other think its VERY hot in here. About 85 degrees. Could that be contributing?

Heres a pic. It may be hard to see though.
Also, don't mind the finger prints or whatever that is in the green. LOL this ones is going to the trash.

 

[artbot]

as far as doing damper swaps, it doesn't mechanically hurt anything. the ink mixing is minimal in that it is just the interior plumbing of the print head and the bottom milliliters of the damper. it's an isolation technique (damper swaps, data ribbon swaps, pump tube swaps)...remember the ink is contaminating in the cap. make sure your cap isn't clogged. remove any screen or sponges, etc and clean so that the latent can wick back up to the print head surface.

if you do a head clean, then print... i'm figuring the issue doesn't happen. or does the ink contaminate that quickly? the print heads are supposed to have pressure or the weight of the ink lightly pressing down into the print head. imagine a chain dropping off the edge of a roof, the bottom of the chain is pulling the rest of the chain off the roof because of it's weight. what's keeping that chain falling is that "it's chained" together. your ink is molecularly chained together by the pressure inside the ink lines. the viscosity (because you mentioned the temperature) doesn't come into play. you can syphon water or straight solvents with these printers. and those fluids have very low surface tension.

do a couple diagnostic tests. after observing and cleaning the interior of the caps.

1) pull the cyan line/damper and let it hang for a while. observe if the damper drips.

2) pull the yellow line/damper and let hang. observe if the level in the damper recedes over about a 10 minute period. if it does, tighten the fittings and test again. if it still recedes change the damper.

3) swap the damper positions and report if the behavior "follows" the ink lines. my suggestion is that for this test, you have to switch ink lines yellow/magenta. because yellow and cyan share the same cap.

4) after that if nothing surfaces, you will need to start seeing if your caps lines are clogged.

 

[bob]

You might want to try the obvious before you descend into a frenzy of dubious damper swapping and other obscurities.

Fact: Yellow starts out contaminated.
Fact: Contamination goes away after a few head passes.

Obvious conclusion: Whatever is contaminating the yellow is a product of having the heads parked on the capping station. It is a static situation as the problem goes away after a bit.

Perhaps you might want to scrutinize your capping station. Maybe it's not draining properly. Maybe it's just old and tired. Maybe it's accursed.

Not that this is the answer but it one should always try the obvious before shooting off into more esoteric territory.

 

[artbot]

hey bob, my answer was "dubious and esoteric" because i'm not going to be around all day. and this guy need to get more than just step 1 (which i said was clean your caps).

and damper swaps are the first thing you do when diagnosing an ink issue. it splits the machine in two. isolating the issue to be above or below the print head.

 

[midnightmadman]

Hey guys. I did a power clean and pulled some ink through the waste lines and everything is perfect again.