Efficiency of PVC Sheaffer Snorkel sacs

[Lunoxmos]

My Sheaffer Snorkel is currently fitted with a PCV sac from David Nishimura's Vintage Pens, and despite ensuring that "the plunger to be depressed more rapidly and deliberately to fill completely", the pen only fills with around 0.2ml of ink. I have checked that the hole in the barrel for letting air out of the pneumatic mechanism is clear, and replaced and greased all the seals. I have also compared the PVC sac to an original latex sac taken from a different Sheaffer snorkel, and the latex sac seems to take up more ink; PVC sacs are in general less pliable than latex and silicone ones, yet I had thought that PVC sacs would still take up a similar amount of ink if the plunger was pushed down rapidly. Oddly enough, I have noticed that more ink is taken up when I push down the plunger more slowly.

 

What are the experiences of other owners of Sheaffer snorkels with PVC sacs, and are there any troubleshooting tips out there which might help increase the volume of ink which is taken up in the pen?

 

[Graywolf503]

Just this week I replaced the sacs in two snorkels with PVC sacs. I also replaced the point seal, O-ring, and blind cap seal, using silicone grease sparingly on all seals. Could not get either pen to reliably take up ink, and when pens did take up ink it was only about 0.3 mL, half of what a snorkel should take up.  I checked all of the seals, and noted that I had two different types of O-rings, one slightly thicker than the other. I made sure that the thicker O-ring (1.2 mm CS x 7 mm ID I assume) was in both snorkels. This did not improve the taking up of ink. I had read about pushing the plunger down rapidly, but this did not seem to improve the situation. Indeed, like you I found that if I pushed the plunger down slower it would more reliably take up ink but still only about 0.3 mL.

 

I leaked checked the barrel, and checked that the hole in the barrel was open. No leaks were found and the hole was open.  Inspection of extra PVC sacs showed them to be stiffer than the latex ones I had. After having worked with this for several days and not being able to improve the situation, I reluctantly removed one of the PVC sacs and put in a latex sac. I did not change any of the other seals in the pen. After changing out the sac, I am able to reliably take up ink and found the amount to be between 0.6 and 0.7 mL.

 

I don't feel that the PVC sacs that I have currently are pliable enough to reliably take up ink and so I will be staying with latex sacs for now. I suppose I could try buying PVC sacs from other suppliers to see if there is a difference, but I'm assuming they may all come from the same manufacturer. I hope this helps, and hopefully other members will contribute their experience.

[Ron Z]

For years I used the PVC sacs sold by Woodbin, but Martin passed a few years ago, 2018 I think, and I snapped up all of the #14 PVC sacs I could. I finally ran low late last year and bought a bunch of David's sacs.  I had to quit using them and go back to latex because they don't work in snorkels. The sac walls are about 3 - 4 thousandths thicker than Martins, so are much stiffer.  The TD filler doesn't develop enough pressure to squeeze the sacs enough to get a good fill.  By  contrast I got the same amount of ink into the pen with a  Martin's PVC sacs as I did with a latex sac, measuring volume drawing water from a tube with markings on it. 

[3rdlakerobert]

2 hours ago, Ron Z said:

For years I used the PVC sacs sold by Woodbin, but Martin passed a few years ago, 2018 I think, and I snapped up all of the #14 PVC sacs I could. I finally ran low late last year and bought a bunch of David's sacs.  I had to quit using them and go back to latex because they don't work in snorkels. The sac walls are about 3 - 4 thousandths thicker than Martins, so are much stiffer.  The TD filler doesn't develop enough pressure to squeeze the sacs enough to get a good fill.  By  contrast I got the same amount of ink into the pen with a  Martin's PVC sacs as I did with a latex sac, measuring volume drawing water from a tube with markings on it. 

I've had the same experience. The sacs from Woodbin were great but since Martin's passing I've been using latex. I've used over 200 Snorkel latex sacs since Woodbin has been gone with no complaints from customers.

[Lunoxmos]

 

2 hours ago, Ron Z said:

For years I used the PVC sacs sold by Woodbin, but Martin passed a few years ago, 2018 I think, and I snapped up all of the #14 PVC sacs I could. I finally ran low late last year and bought a bunch of David's sacs.  I had to quit using them and go back to latex because they don't work in snorkels. The sac walls are about 3 - 4 thousandths thicker than Martins, so are much stiffer.  The TD filler doesn't develop enough pressure to squeeze the sacs enough to get a good fill.  By  contrast I got the same amount of ink into the pen with a  Martin's PVC sacs as I did with a latex sac, measuring volume drawing water from a tube with markings on it. 

Ahhh, yep that makes sense. It's a shame that David's order of PVC sacs aren't performing to the same standard as Martin's ones. Has he been informed about this?

Have you used silicone sacs in snorkels? I'm already using silicone sacs in a few celluloid pens, and it may be my best bet for re-saccing as I prefer to use "boutique" inks, and I understand that a silicone one may at least help ward off the deterioration of my snorkel sac. 

[Ron Z]

There are two problems with silicone sacs.  One is that silicone only sticks to silicone, so you have to use an RTV silicone adhesive to secure them.  The other is that the sacs are gas permeable, which means that gasses get through the sac wall and upset the balance, so the pens have to be stored nib up, or they ooze.  I quit installing them shortly after I bought them, and will only put them in with a caution that if the owner decides that they don't like them, a change to latex will not be free as a warranty repair.

 

Take a look at this article that  I wrote several years ago for more....

[terim]

On 8/8/2022 at 5:47 AM, Ron Z said:

There are two problems with silicone sacs.  One is that silicone only sticks to silicone, so you have to use an RTV silicone adhesive to secure them.  The other is that the sacs are gas permeable, which means that gasses get through the sac wall and upset the balance, so the pens have to be stored nib up, or they ooze.  I quit installing them shortly after I bought them, and will only put them in with a caution that if the owner decides that they don't like them, a change to latex will not be free as a warranty repair.

 

Take a look at this article that  I wrote several years ago for more....

 

Yep, that's been our experience as well. It's very hard to diagnose what the problem is when you get one of those slow leaks, you look at variety of possibilities and it's hard to suspect the sac since the pen fills properly. 

[pajaro]

From the above I conclude that today we should use latex sacs in Touchdown fillers and in Snorkels.  I usually get ten years from a latex sac.  Resac of a Touchdown filler is fairly easy, but Snorkels are a different story, although I actually did resac a Snorkel desk pen, and it works.  I think if you are sensitive to the pen's condition you will be all OK, but how many will take a Snorkel apart to check the sac?  Or at the first sign of a leak send it for repair?  As we are aging, how many repairers are left?

 

[Ron Z]

My experience has been that sac life can be shorter in snorkels.  I suspect from the rubber in contact with the sac guard when it hasn't been coated with talc.  The sac wall on the #14 PVC sacs that David Nishimura sells is about 3 thousandths thicker than the PVC sacs (standard #14) that I got from Woodbin before Martin passed away.  It may not seem like much, but it IS  enough that the sac doesn't get squeezed enough to fill.  Note that I generally did not use Martin's super flexible sacs, latex or PVC, because they weren't stiff enough.  But the standard PVC sacs worked well.

[es9]

2 hours ago, Ron Z said:

The sac wall on the #14 PVC sacs that David Nishimura sells is about 3 thousandths thicker than the PVC sacs (standard #14) that I got from Woodbin before Martin passed away.  It may not seem like much, but it IS  enough that the sac doesn't get squeezed enough to fill. 

Does anyone happen to know if he will be making another run that do not have this problem? Or if anyone else sells pvc sacs that are the proper thickness? 

[Ron Z]

The only other person who had them made them was Martin Smith.  Martin told me that the cost to do a run of all sizes was the price of a small car.  Lots of money to put out.

[PenLovingE]

Resurrecting a dead post to see if th PVC sac issue has been resolved 3 years later. Thank you!

[Ron Z]

Nope, at least not yet.  There is word that someone is working on making PVC sacs, but I gather it will be a while before we see any.

[PenLovingE]

On 4/21/2026 at 5:43 PM, Ron Z said:

Nope, at least not yet.  There is word that someone is working on making PVC sacs, but I gather it will be a while before we see any.

I found these on AliX. With a slow push, I can reliably get 0.5-0.6 mls. Not quite as much as latex but now I can use Pilot's Asa-Gao and Sailor Yonaga!

 

https://a.aliexpress.com/_mNDq0Bl

[Ron Z]

I'm not buying from aliexpress.

[Graywolf503]

Temu?

[Ron Z]

Neither.

[FarmBoy]

The linked sacs look like what would go in an aerometric 51.  They have ribs inside and are tapered. 
 

 

[PenLovingE]

On 5/5/2026 at 7:28 AM, FarmBoy said:

The linked sacs look like what would go in an aerometric 51.  They have ribs inside and are tapered. 
 

 

I know but they work. Here's a listing of a pen I just sold with one of the sacs. Three weeks of writing with no leak. Included is a video of me filling the pen. 

https://ebay.us/m/GzyWJ7

[PenLovingE]

On 5/5/2026 at 7:28 AM, FarmBoy said:

The linked sacs look like what would go in an aerometric 51.  They have ribs inside and are tapered. 
 

 

I know but they work. Here's a listing of a pen I just sold with one of the sacs. Three weeks of writing with no leak. Included is a video of me filling the pen. 

https://ebay.us/m/GzyWJ7