Cork For Pistons

[CS388]

Hello all

 

My last attempt at making a cork seal didn't work out, so I ended up putting the original back seal into the pen (a MB 146).

It worked for a while, but now the ink is getting past it, into the telescopic mechanism - so it's time to try again.

 

I have two corks, from different wine bottles. One is natural cork, the other seems to be refabricated cork - ie small pieces of oork bonded back together (I think).

Doesn't sound very good, but creates an even texture, without the holes and fissures of natural cork.

 

Which would be the best to use to fashion a piston seal?

 

http://i1023.photobucket.com/albums/af351/shoulderhead/corks_zpsepseilrs.jpg

 

(The cork on the left (champagne) is the re-constituted cork)

 

Or am I barking up the wrong tree and shoud I be sourcing cork from elsewhere?

 

Thanks.

[dneal]

Use natural cork. While the end portion of the one on the right looks natural (but too pitted), the side looks strange (as if it's bonded).

 

You can find suitable cork stoppers in most craft shops, and they come in much smaller sizes which require less material removal.

[CS388]

Use natural cork. While the end portion of the one on the right looks natural (but too pitted), the side looks strange (as if it's bonded).

 

You can find suitable cork stoppers in most craft shops, and they come in much smaller sizes which require less material removal.

 

That had never occurred to me. Thanks, I'll do that.

 

Well spotted on the cork; yes, the bottom is real cork, but the top is the refabricated cork - a coarser grade than the champagne cork.

 

Thanks again.

[dneal]

You're welcome. While you're at the craft shop, pick up a bag of 100% parrafin wax (they usually come in beads). Once you've sized the cork, hold it under some melted wax for 30 seconds or so. This will seal any pores and provide lubrication to the piston.

[newlife]

I'm not so much into cork anymore. I bought and recorked lots of pens over the last five years only to make the experience that all my corks have shrunk over the years, although I always used a waxing procedure on them. That's very frustrating, so I mostly use o-rings now.

 

I would use cork nowadays only when I know that this pen will be a daily writer, otherwise I'd have to store all my pens filled with water to prevent the corks from drying. Quite a job if you have many pens!

 

But do whatever you like, making corks for a finally fully functional pen can be a satisfying job! And grown cork is always better than some kind of compound material.

[Ron Z]

The cork on the left is called agglomerated cork, the one on the right is natural cork. The natural cork comes in many grades, the highest being flor cork, which has a much lower number of voids in it. It's also the most expensive. But the voids are there, and there's nothing more frustrating than turning a cork down to the right size only to find that there is a big hole in the area that you need to use.

 

The agglomerated cork is bonded, but in some ways ends up working better because there are no voids in the cork even though it is a bonded material. I have used the agglomerated cork, and haven't had any come back having failed in nearly 10 years. The cork in a piston is supported inside and out, top and bottom, so no opportunity to tear. The synthetic corks are too hard to use in a pen.

 

Use fresh cork, and use silicone grease to lubricate the cork prior to installing in the pen. Some folks soak the cork in paraffin oil (clear lamp oil) and then the silicone grease prior to installing. Don't use wax. I'm not sure that keeping water in a pen with a cork seal accomplishes anything. If the cork has been lubricated with paraffin oil or silicone grease, the water won't reach the cork anyway because the lubricant repels the water and ink.

 

There is some disagreement on using rubber in place of cork. Some pen mechanics like it, some do not. If not lubricated well with silicone grease, and if the 0-ring is tight against the barrel wall, they tend to stick in the barrel, and getting the piston to move again can be quite the challenge. If you do use rubber, make sure it's Viton, which is both chemical and wear resistant. The fit should be tight enough that you get a good seal, but loose enough that the piston moves freely. Actually, that applies to cork as well, but the room for error is a bit bigger.

[newlife]

Hello Ron!

 

I'm not quite sure if you're right saying >>that keeping water in a pen with a cork seal accomplishes anything. If the cork has been lubricated with paraffin oil or silicone grease, the water won't reach the cork anyway because the lubricant repels the water and ink.<<

 

Having made the experience of shrinking waxed corks I believe this happens by evaporation of moisture from the cork. So if this happens from inside the waxed cork, why should it not be possible vice versa, I mean water from outside giving moisture to the cork to prevent shrinking?

 

Greetings from Germany!

 

Klaus

[Ron Z]

I don't think that the cork is shrinking as it drys out. Rather, I think that what is happening is that the cork is compressing over time, so does not, or may not, seal as well.

 

Unlike a wine bottle where the whole end of the cork (which is untreated) is exposed to liquid, a cork seal in a pen is not. There is relatively little clearance between the end of the piston which holds the cork on and the inside of the pen barrel - a few thousandths at most. Not much surface area to wet even if that were effective.... see below. With that small, lubricated area being the only place where the liquid comes in contact with the cork, how could it moisturize the whole cork?

 

The inside of the cork is pressed against the piston, the outside of the cork presses against the barrel wall, the ends are held in place by a flange, the cork more or less sealed by a water repellent lubricant. The whole purpose of the lubricant and cork is to present a barrier to liquid. Cork in itself resists absorbing moisture, which is why it is so effective when used in flotation devices and seals. I just can't see that keeping the pen full of water would be at all effective. What it does do is to provide a moisture rich environment for mold and bacterial.

 

Then there's what I found when I did a fair amount of reading about corks, which is that it is not possible to rehydrate a cork. The reason I went digging was that I bought a box full of corks that I thought I could use for pen repair. But they were dry and a bit brittle, so I looked for a way to revive them. You can't. Do a little noodling around about the shelf life of corks, and rehydrating or reconditioning.

[newlife]

Maybe compression is the clue. On the other hand I hear from people having bought a vintage pen who doesn't take enough ink, they leave it filled with water and after some time claim the piston works well again!? Anyway, many thanks for your helpful tips concerning cork and Viton, too.

 

Did you ever try glycerine to make cork more hygroscopical? Just an idea I had lately. Maybe it could help to revive cork?

[dneal]

Be careful buying liquids labeled "paraffin". Outside the U.S., it can be anything from mineral oil to kerosene.

 

Although everyone has their preferences, there's nothing wrong nor uncommon about using paraffin wax.

[Ron Z]

Did you ever try glycerine to make cork more hygroscopical? Just an idea I had lately. Maybe it could help to revive cork?

 

From what I've read, once cork dries out completely it starts to break down and can not be revived.

[pavoni]

With a considerable number of vintage piston-fillers in my collection(s) laying unused in pen cabinets since being serviced years ago by mainly either Max, Tom or Francis, I have often pondered on this issue of storage and hydrating cork seals. However, I have resigned myself to simply replacing them or having them replaced as and when I need to.

 

After seeking opinion (divided), I eventually decided to keep/store my valuable pens dry on the basis that the corks were (probably) properly prepared by the aforementioned guys and as such, ought to last a reasonable time before becoming past their best.

 

I admit to being scared off by the thought of the likely consequences of maintaining a moisture-rich environment within one of my valuable celluloid vintage pens.

 

Thanks for the discussion guys. I really want to find the time to do my own corks. I have cork, tools, pens but lack the time currently (work and family commitments) to do the task justice and gain the satisfaction newlife makes mention of.

 

Just a thought on CS388's problem, would the reason for ink getting past the cork on a vintage celluloid barrel be due to the lack of uniformity/warping of a vintage celluloid barrel? Wouldn't natural cork be better than a synthetic seal in such a scenario?

 

Pavoni.

[dneal]

With a considerable number of vintage piston-fillers in my collection(s) laying unused in pen cabinets since being serviced years ago by mainly either Max, Tom or Francis, I have often pondered on this issue of storage and hydrating cork seals. However, I have resigned myself to simply replacing them or having them replaced as and when I need to.

 

After seeking opinion (divided), I eventually decided to keep/store my valuable pens dry on the basis that the corks were (probably) properly prepared by the aforementioned guys and as such, ought to last a reasonable time before becoming past their best.

 

I admit to being scared off by the thought of the likely consequences of maintaining a moisture-rich environment within one of my valuable celluloid vintage pens.

 

Thanks for the discussion guys. I really want to find the time to do my own corks. I have cork, tools, pens but lack the time currently (work and family commitments) to do the task justice and gain the satisfaction newlife makes mention of.

 

Just a thought on CS388's problem, would the reason for ink getting past the cork on a vintage celluloid barrel be due to the lack of uniformity/warping of a vintage celluloid barrel? Wouldn't natural cork be better than a synthetic seal in such a scenario?

 

Pavoni.

 

I've got some 60+ year old Kaweco's with what appear to be the original cork (based on the dried ink mainly). I left the original cork in them because they still seal the barrel. In fact, a 712 Sport that appears unused, had a serviceable cork with a completely disintegrated celluloid assembly (the part that goes through the cork and screws into the piston shaft). The point is - I don't worry about storing them "wet". They seem to last a long, long time and I can make another one if need be.

 

They are a pain in the butt to make, and one day I might get a set of the punches David Nishimura sells (no affiliation) and see if that's easier than using a Dremel. You might give them a try if you feel like making your own.

 

The last point you make is something I noticed with one specific pen. The portion of the barrel by the ink window is a larger diameter than the other end of the barrel. When the piston is completely extended, the cork loses its seal (not that it really matters in that position). I have no idea why this is. Perhaps the pen was stored with the piston in that position, and the old cork prevented it from shrinking as much. Perhaps the two different celluloids shrank at different rates. I may be that someone attempted to remove ink stains in the past, and removed material which created a larger diameter in that portion of the pen...

[Ron Z]

 

 

would the reason for ink getting past the cork on a vintage celluloid barrel be due to the lack of uniformity/warping of a vintage celluloid barrel? Wouldn't natural cork be better than a synthetic seal in such a scenario?

 

Possibly, and possibly. I have seen pens where there is a change in diameter over the length of the barrel, verified by measuring with a bore gauge. I've tried to repair these, but in most cases the difference was enough that I couldn't get a happy medium i.e. a seal that was snug enough to seal and not leak at one end, but not too tight at the other end. It's usually the back end, where the piston seal rests with the mechanism retracted as in a filled pen. I one case I put a ring to stop the piston from traveling to the fully retracted position, which kept it down in the narrower part of the barrel. Granted, it reduced the amount of ink that the pen would hold, but the pen was usable. Boring the barrel to the slightly larger ID was not an option, and even if it was I would consider it to be a risky procedure.

[CS388]

Many thanks for all the replies. Most informative and much appreciated.

I feel mentally equipped.

 

Thank you, Pavoni. I like your vintage celluloid/lack of uniformity theory.

A theory which holds water, even when the pen doesn't.

But, in this instance, it's definitely the cork. It has shrivelled beyond service. Couldn't pull a full tank in.

 

I hope it's not sacrelige to say this (having started a thread about cork) but I'd swap it out for an elastomer seal in an instant.

Got them in my celluloid 144's and get consistent good performance from them year after year.

 

I'll update the thread with the finished product, when it arrives.

(Which could be months away, or weeks away or tomorrow etc.)

Thanks again. It's a big help.

 

Enjoy

[CS388]

Oh dear, looks like I never did update this thread, as I'd promised I would...

 

First off, here's the photograph of the two cork types, which Photobucket removed:

 

 

And thanks to everybody who contributed, for the help. I made quite a few cork seals and now I replace them as and when I need. All the above remains true. However, I just silicon greased the last few seals I fitted, instead of the hot wax (tea-light) dip. Seems to be working well up to now.

 

Thanks again to all for the help.

 

Regards, CS

[stephen_schachter]

Two years later, again.

 

Why does no one accept empirical/anecdotal information from anyone but themselves?

 

My admittedly limited experience with the cork seal in an early Moore safety pen is that it is possible to resurrect the seal by first soaking the back end of the barrel where the seal is located in water for a few hours, and then re-assembling the pen and filling it with water and letting it sit barrel end down for a while. There is now resistance when the nib is pushed out and leaking through the seal is either totally eliminated or greatly reduced. Of course I have no idea what will happen tomorrow, or when I use ink in the pen instead of water or whether these results indicate anything useful or permanent. But I have demonstrated (to my self) that the seal has been at least partly rejuvenated. By the way, this was not my idea, someone in the blogesphere suggested it earlier. Does anyone want to comment on why this seems to be working and is thus something reasonable to try before replacing the seal?

 

Cheerfully,

 

Steve