Smooth As A Baby's Bottom – Or Not

Disclaimer: In this article, we discuss methods for altering fountain pen nibs. Alter your own pens at your own risk. Please be careful, but if something goes wrong, don't blame us!

Explanation of the problem

The Kaweco AL Sport is one of the fountain pens that I coveted since the first time I browsed through the fountain pens section on JetPens. It was sleek, simple, and aluminum. Other people who reviewed them said such great things about them. I knew that I would buy one at some point.

I ended up buying one at the end of the year and was blown away by the build quality of the pen. After inking it up and trying to write with it, I became frustrated. The ink just wasn't coming out consistently. I chalked it up to the fact that it was new and maybe the ink needed a little time to saturate the feed. A few hours later, same problem. Well that's weird.

Several days later, I emailed JetPens to see what I could do about the problem. They suggested giving the pen a thorough cleaning. Sometimes there is a chemical residue on the nib from the factory that can cause skipping and hard start issues. Perfect! After a thorough cleaning and a 24-hour soak, I inked the pen up again and tried writing with it. (I'll also note that they were extremely willing to send a replacement nib if I still had trouble. Thanks, JetPens!)

Again, a terribly frustrating experience. It would never write on the first stroke, and was incredibly inconsistent once it started writing. It felt like writing with a pen that only had a drop of ink left. Downstrokes were usually dry or non-existant, and other strokes were less sporatic but still skippy. I was discombobulated.

writing sample.jpg

My first hunch was that there was a problem with the feed. After a lot of searching online and no real results, I gave up and ordered a new nib unit from JetPens. I thought the nib that came with the pen was obviously a dud and I was tired of trying to figure out the problem. I thought it was too much to ask that a pen that cost $76 needed so much troubleshooting to make it write.

The new nib came in, and I installed it in the pen and started to write.

I started seeing red when I realized I was having the exact same problem as the other nib. OK, that's it. I came close to using the AL Sport as a ninja throwing star on my poor office wall.

After I cooled off, I started doing more research on the pen. It was disheartening to find so many glowing reviews of the Kawecos. The negative points I found described the pen as not writing at all, and Kaweco or the seller quickly resolved the issue with a new nib that wrote perfectly.

For a while, I wrote the Kaweco brand off entirely. Never again will I buy one of their pens!

So, baby's bottoms are bad?

Eventually, I stumbled on this article by Evan Brus on his AL Sport. Finally, after so much searching, I found someone with the exact same issue. Plus, he put a name on the issue. Baby's bottom.

Basically, baby's bottom is a problem with the nib in which the tines come together and form a small inverse pool instead of a flat surface where the nib meets the paper. Since the part of the nib that delivers the ink isn't really touching the paper, the result is bad starts and inconsistent ink flow.

babies bottom.jpg

Image above via Richard Binder's nib smoothing guide

Now that I knew the name of the problem, I found an abundance of tips and advice on how to fix the issue. Perfect.

I'd watched this video a couple of times about how to smooth a nib, but it doesn't cover baby's bottom. It's still an excellent video and very instructional for making scratchy pens smooth.

After a quick search, I landed on this tutorial by Stephen Brown on how to get rid of baby's bottom on a nib. Absolutely fantastic. The video is about 14 minutes long, in which Stephen demonstrates the technique on a Mont Blanc.

As always, it's extremely important to note that working on your pen is something you choose to do completely at your own risk. Any damage or voiding of warranties is entirely your fault. If you don't want to risk it, send your pen to a professional.

The tools

So, what do you need in order to smooth out that baby's bottom? A few things.

First, you need micro-mesh pads. These are similar to sandpaper, but they're soft and attached to foam. This makes it more difficult to cause too much grinding. Anderson Pens sells a great package of 9 different pads for smoothing and polishing. This is a great package because you need these varying levels of grit in order to properly correct the nib.

I used a nail file that I found at the local store. It has four sides of varying grit and is foam-backed on all sides. It's not the best, but it works well. I plan on purchasing a pack of pads from Anderson Pens with my next order.

Next, you need a small amount of water. I kept mine in a syringe.

It's also handy to have a rag nearby to clean up the water and ink from the pads.

And, finally, you need a pen that is troubled by the terrible baby's bottom syndrome. The pen needs to be inked. Otherwise, you won't be able to test the nib and ink flow after each smoothing cycle.


The technique

Before you start grinding your nib, please be sure to check that the nib tines are properly aligned. This video is an excellent resource that you should definitely watch. If the tines are misaligned when you start grinding, your problem won't get better.

The technique is fairly simple. You start with the coarse grit pad first, and then work down to the finest grit. You perform the exact same actions on each pad. The idea is that the coarse pads grind the nib down very slightly in order to remove the baby's bottom, and as you move to the finer grit pads, the nib becomes smooth and polished for a glassy writing feel.

  • First, start with the coarsest pad you have. Place a drop or two of water on the pad. The water helps lubricate the nib.
  • Next, place the nib in the water drop and starting drawing figure-eights. Complete no more than 8 figure-eights. Use a light pressure, similar to when you write.
  • Next, draw 8 infinity signs on the pad. Again, use a normal pressure.
  • Next, blot up the water and ink with a rag or towel, and move to the next pad. The next pad is the one that is one step below the most coarse grit.
  • Repeat the steps. A drop or two of water on the pad, draw 8 figure-eights and 8 infinity signs, blot, and move to the next finer grit pad.

Keep doing this until you complete the process with the finest pad you have. After that, try writing with the pen. Is it smooth and perfect? You're done! Is it still having problems with ink flow? Repeat the process. Keep smoothing until the pen is writing correctly. Don't go overboard. Remember to only draw 8 signs each on each pad. If you grind too much, your pen will develop a different problem that you can't fix.

With my Kaweco, I went through the process 5 or 6 times. After that, it writes like a dream.

Happy writing

I'm happy to say that my Kaweco AL Sport is now one of my favorite pens. I've also tuned up a couple of my other pens that have slight nib smoothness issues. This is a great skill to practice and hone since it seems like a lot of nibs these days aren't quite perfect from the factory.

If you want to try this out, I'd recommend practicing on a cheap pen. With the Kaweco, a spare nib unit costs about $11 from JetPens. The pressure isn't too high in that case. However, when my Lamy 2000 had some slight issues, I let Mike Masuyama fix it. I don't want to ruin a premium fountain pen with an irreplaceable gold nib. Let the experts handle that one! There are plenty of nibmeisters out there who can make that nib sing.

I'd be curious to know if you've had any problems with nibs. Have you tried fixing them or had someone else fix them?

(You can find more from Jeff online at Draft Evolution, Twitter, and

Posted on April 23, 2014 and filed under Fountain Pen Maintenance.