Do Aerometrics need to be converted?

[InkReservoir]

So I’ve seen a somewhat “trend” of people restoring some 51 Aerometrics and during the process they convert them to cartridge converters using a brass fitting. 
 

I am wondering, is there a particular reason why? From what I understand, the Aerometric sac stands the test of time far better than a Vacumatic sac. 
 

In cases where it has failed, there are parts available to replace the sac inside the protector, so I’m curious as to why people make these permanent conversions. Is it purely for convenience? 
 

I always loved the aerometric filling system and think it’s pretty convenient as is. Perhaps I am missing something or being naïve though, so please let me know if I am! 

[inkstainedruth]

Sorry, no clue.  I LOVE my vintage 51 Aeros, because 95% of the time all they need is a good flushing out and are then ready to fill and write.  The 51 Vacs might need more in the way of repairs, but I like those as well (I have one with a nicely tuned EF nib that is my "go to" pen for if I have to do research and take copious notes in the process; and last fall lucked into a Cordovan Brown 51 Vac at an estate sale, in the box for a Parker 45 (which I had gone to the sale to look at) and which had two spare press-bar converters along with the one installed IN the 45).  Wasn't till I got outside after paying for the two pens and the 2 spare converters that I looked at the other pen carefully and was suddenly going, "OMG -- is this Cordovan Brown!"  Five bucks US for the two pens and the two spare converters and the box, and the estate sale people thought I was nuts because I DIDN'T want the little metal body BP that was also in the box (they told me it was made by Cross and I said, "I don't care -- I don't want it!") because it didn't have a cap and because I didn't know how easy it would be to get a replacement fill for it; and also because it was maybe 3" long and MAYBE 3/8" in diameter at MOST (seriously -- it would have maybe made my Parker Vectors look "fat" in comparison... ).

Ruth Morrisson aka inkstainedruth

[Number99]

  On 3/29/2025 at 1:16 AM, InkReservoir said:

convert them to cartridge converters using a brass fitting. 

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I purchased it over a year ago without thinking because I prefer to inject a small amount of ink into the cartridge and use it. I really didn't think anything of it.

The fittings I received were all brass and the passage way for the ink was also made of brass.

When I opened the package and smelled the brass scent,  I was concerned that brass might corrode with ink in the future. I could have installed it and see how it looked temporarily, but I decided not to modify it because I would have had to remove the breather tube and purchase various parts and tools to put it back together again.

 

This may not be the comment the OP is expecting. If the fittings were stainless steel I would not have hesitated to install them.

 

 

Edited March 29 by Number99
Change in wording.

[IThinkIHaveAProblem]

HELL NO.

the Aerometric sac is just about indestructible.

I mean, yeah, apparently some fail, I've never had one fail.

I have one to replace, but that's cause I got the soggy nipple problem with that pen, that's not a sac failure!

it's a neat, but IMO unnecessary idea. 

IF Aero sacs were super prone to failure, and hard to source? eh... maybe.

but since the sacs DONT fail, this is a solution to a problem that doesn't exist

 

[Number99]

As I explained above, I am neither for nor against this modification.

However, I would like to hear from people who have actually done it, and I think the convenience of the C/C filler, the efficiency of cleaning the inside of the pen, and the ability to easily refill ink on the go would be beneficial.

 

There is a similar kit for the Hero 100 that only allows the use of a converter, but it is popular because it comes with a vent tube connected to the feeder, converter, and disassembly tool and sells for about the same price as the Parker 51 kit.  ( Incidentally, I am not interested in the case of a modification only for converter adaptation.)

This is not a replacement for a repair, but a modification of a fully functional fountain pen, which means that even modifications of a fully functional Aerometric Filler fountain pen are in demand.

 

The important point here is that since each person has his or her own opinion about this modification, it is necessary to avoid the argument that the affirmative is right or wrong.

 

Edited March 29 by Number99
Typo correction.

[InkReservoir]

  On 3/29/2025 at 3:58 AM, inkstainedruth said:

Five bucks US for the two pens and the two spare converters and the box

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I always hear of people having this luck, one day it’ll be my turn! 

That’s an amazing deal and I legit laughed at the Cross comment! 😂

[InkReservoir]

  On 3/29/2025 at 10:13 AM, Number99 said:

think the convenience of the C/C filler, the efficiency of cleaning the inside of the pen, and the ability to easily refill ink on the go would be beneficial

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That’s what interests me is peoples perspectives on conveniences. Typically to fill my Aero, it’s 4 pumps on the bar and I’m good for a few day of writing and it’s the same with cleaning which to me is no less convenient than twisting the piston on a converter. 
 

Granted if I’m cleaning for longer storage it’s usually a pen flush, followed by some distilled water then I leave it to air dry. 
 

The only other point I’ll say is that I kind of view cleaning a pen as a relaxing ritual type thing, so I’m usually not in a hurry to get it over with. I can see it from others side who want a quick job however.

 

Thanks for sharing your thoughts! 

[Estycollector]

I've always been the odd sort that felt filling a fountain pen was an elemental part of the experience. Even in the Lamy FP's I use a converter. I enjoy the lever, "aerometric", and vacuum fill systems for their tactile enjoyment. 

[PAKMAN]

The nice thing about Aerometrics is that they are pretty much bulletproof and rarely need replacing. They can be used with most inks without problems. I wouldn't use shimmer inks but not due to the filler but due to the difficulty in cleaning out the feed if it becomes rocked up. 

[inkstainedruth]

  On 3/29/2025 at 11:56 AM, InkReservoir said:

I always hear of people having this luck, one day it’ll be my turn! 

That’s an amazing deal and I legit laughed at the Cross comment! 😂

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Yeah, the estate sale people thought I was crazy.  (OTOH, the guy in charge was handing out Dunkin Donuts to people in line for free before the doors opened....)

And don't get me wrong -- I have a few Cross FPs.  I LOVE my two Solos and would love to get a few more in other colors (and preferably with other nibs as well).  I also have an Adventura which isn't a bad writer, which I got in trade for a pen that wasn't repairable and would become a "parts pen".  And I have a Penatia (a Cross sub-brand) that I found at an antiques store a few years ago in the next county south.  Asked the woman who ran the place what converters it would take and she said that her "pen guy" told her "International Standard".  Then a guy came out of the back and it turned out to be a guy from my local pen club!   The problem, though, that when I went to a show that fall, NONE of the International Standard converters vendors had fit the pen -- but a *Cross* converter someone had worked just fine (go figure).  I just have to figure out how to re-glue the rubber coating and trim onto the barrel in spots.  

OTOH, I picked up what turned out to be a Cross Verve for super cheap at a place that re-sells donated art supplies.  Paid a buck plus tax.  Brought it to a pen club meeting because I didn't know what it was, and someone pulled up information on his laptop and I was APPALLED by the prices being asked for those things! Apparently there was some big fancy "release" party in NYC when they first came out -- but the pens are just weird.  The nib is in two pieces, with gaps on the sides of the feed.  And I haven't figured out how to hold it far enough back on the section to NOT get ink all over my fingers!   And then when the guy told me how much a different color one had sold for on eBay?  I was like "What drugs are these people on, to be paying that much for something that's such a PITA to write with?"  (I just looked and most of the ones on eBay at the moment are close to $300 US, and I paid a BUCK plus sales tax for mine).

Ruth Morrisson aka inkstainedruth

[FarmBoy]

  On 3/29/2025 at 10:36 PM, inkstainedruth said:

Yeah, the estate sale people thought I was crazy.  (OTOH, the guy in charge was handing out Dunkin Donuts to people in line for free before the doors opened....)

And don't get me wrong -- I have a few Cross FPs.  I LOVE my two Solos and would love to get a few more in other colors (and preferably with other nibs as well).  I also have an Adventura which isn't a bad writer, which I got in trade for a pen that wasn't repairable and would become a "parts pen".  And I have a Penatia (a Cross sub-brand) that I found at an antiques store a few years ago in the next county south.  Asked the woman who ran the place what converters it would take and she said that her "pen guy" told her "International Standard".  Then a guy came out of the back and it turned out to be a guy from my local pen club!   The problem, though, that when I went to a show that fall, NONE of the International Standard converters vendors had fit the pen -- but a *Cross* converter someone had worked just fine (go figure).  I just have to figure out how to re-glue the rubber coating and trim onto the barrel in spots.  

OTOH, I picked up what turned out to be a Cross Verve for super cheap at a place that re-sells donated art supplies.  Paid a buck plus tax.  Brought it to a pen club meeting because I didn't know what it was, and someone pulled up information on his laptop and I was APPALLED by the prices being asked for those things! Apparently there was some big fancy "release" party in NYC when they first came out -- but the pens are just weird.  The nib is in two pieces, with gaps on the sides of the feed.  And I haven't figured out how to hold it far enough back on the section to NOT get ink all over my fingers!   And then when the guy told me how much a different color one had sold for on eBay?  I was like "What drugs are these people on, to be paying that much for something that's such a PITA to write with?"  (I just looked and most of the ones on eBay at the moment are close to $300 US, and I paid a BUCK plus sales tax for mine).

Ruth Morrisson aka inkstainedruth

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All this talk of pen buys reminds be heard a story once of a person getting a Plum 51 for a few bucks at a garage sale or something. 
 

 

[VacNut]

  On 3/29/2025 at 1:16 AM, InkReservoir said:

So I’ve seen a somewhat “trend” of people restoring some 51 Aerometrics and during the process they convert them to cartridge converters using a brass fitting. 
 

I am wondering, is there a particular reason why? From what I understand, the Aerometric sac stands the test of time far better than a Vacumatic sac. 
 

In cases where it has failed, there are parts available to replace the sac inside the protector, so I’m curious as to why people make these permanent conversions. Is it purely for convenience? 
 

I always loved the aerometric filling system and think it’s pretty convenient as is. Perhaps I am missing something or being naïve though, so please let me know if I am! 

Expand  

I am not familiar with the “trend” as the filler and pen are near bulletproof. I am curious as to the benefit of a cartridge, as it seems more limiting than a pen that can be refilled. It seems one would be at the mercy of the cartridge mfr. There may also be a greater potential for leaks.

 

Parker tried making the 51 Aerometric into a cartridge pen in response to waterman cartridge pen. They dismissed the idea. Maybe cartridges back then were less dependable? 

[InkReservoir]

I used the word trend loosely, I’ve just seen a few videos around these conversions and the comment section on each was raving with people wishing to convert theirs also. 

The overall restorations were high quality so that probably swayed the comments as well I’d think! 

[inkstainedruth]

  On 3/29/2025 at 10:57 PM, FarmBoy said:

All this talk of pen buys reminds be heard a story once of a person getting a Plum 51 for a few bucks at a garage sale or something. 
 

 

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That was definitely NOT me....  But I did pick up what turned out to be a Parker 41 for 50¢ in a shoebox full of mostly ballpoints at an estate sale a number of years ago....

Ruth Morrisson aka inkstainedruth

[InkReservoir]

  On 3/30/2025 at 12:01 AM, inkstainedruth said:

That was definitely NOT me....  But I did pick up what turned out to be a Parker 41 for 50¢ in a shoebox full of mostly ballpoints at an estate sale a number of years ago....

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And I’m betting it was in flawless condition as well right? 
 

I really need to check out more estate sales, I’m sleeping on some gem finds it would seem! 

[Mercian]

"Do Aerometrics need to be converted?"

 

 

Heresy!

 

I say this as someone who owns many Parker c/c pens. And two aerometric "51"s, and one aerometric 'Junior' Duofold.

 

The 'aerometric' fill system in the Parker "51" allows air pressure inside the pen to equalise with the air pressure outside the pen. The pen was even advertised as being suitable for use on the (poorly pressurised) airliners of its era.
Part of the system that enables the pressure-equalisation to happen is the lengthy 'breather tube' that runs from the back of the pen's feed and up into the clear and flexible plastic sac that holds the ink.
If anyone were to 'convert' an aerometric "51" to use cartridges, this air-pressure equalisation mechanism would be lost.

 

So what?
Well, if any of you remember seeing this, one of King Charles III's first public engagements after his accession to the throne was a trip around the four 'nations' that comprise the UK. When he tried to use his fountain pen to sign a document in Northern Ireland (after flying there), it famously burped/leaked its contents, leading to HM having ink all over his hands and complaining about this happening "every bloody time".

 

 

And I urge you, dear reader, to pay attention to what @VacNut said:

 

  On 3/29/2025 at 11:09 PM, VacNut said:

Parker tried making the 51 Aerometric into a cartridge pen in response to waterman cartridge pen. They dismissed the idea.

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The Parker "51" was rolled-out in 1940. The vacumatic version was made until 1948. The aerometric version was made from 1948 to ~1977 (here in the UK at least).

The c/c version of the "51" was produced for about one year. One year only. What does that tell everyone?

 

If anyone wants to have a c/c version of the Parker "51", they can either look for one of the c/c versions from 1961/2, or perhaps try buying one of the post-2020 c/c pens that modern Parker sells under the name 'Parker 51' (as opposed to the vintage pen's trademarked name of 'Parker "51" ').

Thou shalt not defile the aerometric fill system that Parker's engineers devised!

 

Here endeth the Rant

[IThinkIHaveAProblem]

  On 3/30/2025 at 2:06 AM, Mercian said:

"Do Aerometrics need to be converted?"

 

 

Heresy!

 

I say this as someone who owns many Parker c/c pens. And two aerometric "51"s, and one aerometric 'Junior' Duofold.

 

The 'aerometric' fill system in the Parker "51" allows air pressure inside the pen to equalise with the air pressure outside the pen. The pen was even advertised as being suitable for use on the (poorly pressurised) airliners of its era.
Part of the system that enables the pressure-equalisation to happen is the lengthy 'breather tube' that runs from the back of the pen's feed and up into the clear and flexible plastic sac that holds the ink.
If anyone were to 'convert' an aerometric "51" to use cartridges, this air-pressure equalisation mechanism would be lost.

 

So what?
Well, if any of you remember seeing this, one of King Charles III's first public engagements after his accession to the throne was a trip around the four 'nations' that comprise the UK. When he tried to use his fountain pen to sign a document in Northern Ireland (after flying there), it famously burped/leaked its contents, leading to HM having ink all over his hands and complaining about this happening "every bloody time".

His mother used to use an aerometric Parker "51". You never saw her complaining about her pen leaking.

 

 

And I urge you, dear reader, to pay attention to what @VacNut said:

 

 

The Parker "51" was rolled-out in 1940. The vacumatic version was made until 1948. The aerometric version was made from 1948 to ~1977 (here in the UK at least).

The c/c version of the "51" was produced for about one year. One year only. What does that tell everyone?

 

If anyone wants to have a c/c version of the Parker "51", they can either look for one of the c/c versions from 1961/2, or perhaps try buying one of the post-2020 c/c pens that modern Parker sells under the name 'Parker 51' (as opposed to the vintage pen's trademarked name of 'Parker "51" ').

Thou shalt not defile the aerometric fill system that Parker's engineers devised!

 

Here endeth the Rant

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this.

 

[VacNut]

FYI, the 51 cartridge prototype is 💩.

 

I have always considered the 61 as an anomaly, as the later 41,45, and 21 all use a aerometric type filler.

 

Regardless, it shows the long enduring qualities of a 51, if it can be converted to a cartridge filler 70 years after its inception.

[Glenn-SC]

  On 3/30/2025 at 2:06 AM, Mercian said:

Thou shalt not defile the aerometric fill system that Parker's engineers devised!

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And that is why every FP made by Parker (and everyone else for that matter) since 1948 uses an aerometric filling system.  

[Number99]

Although I was not able to convert my own pen, I would like to express my appreciation and respect to those who introduced the conversion kit on the Parker forum and reported how they did it.

I think it was informative to be able to see with my own eyes what the conversion kit is really like.