I've found some interesting posts talking about how to increase flow, but nothing addressing this issue:

in a number of my inexpensive (Chinese) pens, flow will only start if I "chug" the converter until I see ink saturating the feed, usually about 1/4 of the way down; after this point a pen will write marvelously for about a page and then dry up. Then I have to chug the converter another 1/4.

The pens that do this are my Duke 2009, and a Kaigelu 308. Sometimes, with some inks my Dancheron Paris Amber and my Dannitu 100 will do this, but actually I've seen the Dancheron behave itself with Skrip Red (Skrip inks are known for their ease of use).

Are there any fixes for these pens? It's difficult to convince people that FP's are not inconvenient when they see me unscrewing the barrel to get more ink to flow to the nib. (But otherwise, this is not a nuisance to me, since these pens all write fabulously and were obtained for $10 and under!!)

After you feel it dry, and before you work the converter, is the air bubble at the top, back end, or is it at the nipple? If it's at the top, I would imagine that as not enough air going in. If it's at the top, then maybe it just needs to fall down. Is there any way to take one of the plastic pellets from a cartridge and stick it in the converter?

I'm not exactly certain but it seems to me that air never gets into the converter to displace the ink (or whatever happens when air enters the converter in all my normal pens). I think the feed just empties of ink, then I have to chug the converter to fill the feed with ink again.

I don't have a converter for the Dancheron, and when it does this, the solution is to squeeze the cartridge. But my last cartridge cracked after doing that enough times.

Hi,

This is the general approach to this problem. I noticed that you said that this happened with a cartridge also so the second possibility is
more relevant for you, but I am posting the general approach that I take in similar cases.

First lets try a cartridge (or another converter that you know it worked on another pen). Does it now work with no problem?
If yes, then throw away the other converter. Some cheaper (and some no so cheap) pens use converter with bad surface properties.
If you are careful when you open the pen when it stops you may see the ink "stuck" near the top of the converter and a big air buble close to the opening. Alternatively you may add a small ball or spring inside the converter and shake (lightly) when this problem occurs.
Also this may be ink dependent behavior.

Now suppose that the previous step did not work. This means that the converter works but another problem exists with the feed. Since you said that the pen worked flawlessly for a while, this is not an issue of cleaning debris etc (although it does not hurt to wash the feed one more time). This is often is refered to as the "vapor lock" problem. Vapor lock is the term used to describe the problem faced when the feed and/or the properties of the ink and feed material (usually modern plastic) are such that make the passage of air bubbles into the converter difficult/impossible. This is a bit more complex. One possibility is to use a more easily flowing ink. Common example is PR's Tanzanite (the laxative of inks). Of course restricting the inks that can be used in a pen is always furstrating so modifying your favorite ink with dishwater liquid (for hands) is an option (just a tiny amount can take you a long way).

Another possibility is to do some feed surgery (widening ink channels) - this is complex and can worsen the problem if the wrong modification is made. An even more extreme solution can be found in topic 299

Other possibilities exist (bad contact between nib and feed etc.) but I dont think are relevant here.
Would love to hear other opinions on this as it is one of the most furstrating problems (mainly in modern nibs).

AZ

PS> Got your snail mail. Hope to reply soon.

What was the outcome of that procedure? Are there any pictures of it? I'm not visualizing this "surgery" very well. I don't see how the new hole lines up with anything else.

And what other techniques are there to widen those ink channels? I think that I get a vapor lock on some of my pens on occasion, and maybe all the time on some. I'd like to find a way to fix that.

UPDATE: I have three pens that have this problem: The Duke 2009 (Charlie Chaplin, I call it "Dark Helmet"), A Kaigelu 308, and a Dancheron Paris Amber. The Dancheron and the Duke both work FINE until there's no more ink left when I change the ink. I haven't tried everything, but I will surprisingly admit that Noodler's UK Eternal "Empire Red" has found its home in these two pens. Yes, everyone was yelping about the UK Eternals having horrible flow. I have had NO problems with Empire Red at all.

I still haven't solved the problem with the Kaigelu 308. My guess is it needs to be "drilled" but of course I'm nervous to do that. Actually, I should try Empire Red in it first...

AZ: no bubble forms in the converter. I imagine air is not getting in through ("vapor lock"??). Can't switch the converter on this one, since it screws in. Adding A LOT of detergent-water had no effect (I did it little by little to the point where I thought it was pointless to add any more!).

Another possibility exists and that is that there is a bit of dried ink/crud within the feed that is slightly restricting flow. If you have access to an ultrasonic cleaner, a dip in the bath with the feed and nib will fix the problem. I find that this occurs frequently with modern pens especially if you let them dry out by using up all the ink in the converter and not flushing them if you are not going to use them for several days. Poor design of feed channels? I suspect that this is the problem with many of them.
Rob