From this thread (and pasting in case seomeone doesn't have an FPN membership), in regards to just putting on your own sac (I would also recommend a PVC sac, or silicone if the material is able to be damaged by PVC like celluloid and other soft plastics).
http://www.fountainpennetwork.com/fo...-demonstrator/
For later reference, all modern re-issued Conklin Crescent-Fillers are easily serviceable. The first models had aerometric sacs that were held in place with a rubber O-ring, but for later models the sacs are glued to the feed nipple and there is less of a chance for leaks or filling problems.
These pens can be dismantled and I have used a pair of section pliers and rubber gripping material sold by Richard Binder to unscrew the barrel from the nib section. The barrel and outer nib section unscrew between the metal ring on the nib section and the barrel. Sometimes, heat may need to be applied at the point where the barrel and section meet. Hot water can help loosen the seal. Be sure the crescent filler button is locked in place. I hold the barrel with gripping material and rotate the section with the section pliers.
There is an inner section holding the nib and feed, but it is a little tricky to unscrew. The Endura model has the same arrangement and seems to unscrew easily. The nib and feed are friction fit and it is easier to simply pull them straight out for thorough cleaning or adjustment. Notice the registration guide, in the inner section, for lining up the nib and feed for reinsertion into the section.
The sac, according to a White Rubber Company gauge, is a number 17 (.266 inch diameter/ 73 mm), and it is 2 7/8 inches long. The nibs are a number 6 and are interchangeable with Goulet JoWo number 6 nibs.
The new, re-issued Conklin Crescent Fillers (aerometric-filled) pens are simple to maintain and they are terrific, classic-style fountain pens. If the seal for the sac at the feed nipple is secure, leaks will not occur and the section should remain relatively clean.
When re-attaching the barrel to nib section, the nib and crescent filler should line up, just as the crescent filler lines
up with the clip when the cap is screwed on. That is a nice touch and I appreciate Conklin's attention to detail.
Regards, Robert
grainweevil (April 9th, 2020)
A few years back I bought a LE demonstrator Crescent filler that leaked. The thing that I noted was that it was difficult to press the present filler as if the ink channel was blocked and did not allow the sac to expel the air. It soon became apparent the glue holding the sac to the nipple had failed and ink was leaking inside the barrel. Something I would not have known if it had not been a demonstrator. I ended up sending it back to the retailer and getting as a different pen. I share my experience and regret not sending it back for warranty repair.
Fountain Pen Sith Lord | Daakusaido | Everything in one spot
where is the best place online to buy sacs now ?
Pen Sac Company.
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Only David Nishimura has been making silicone sacs, and only Martin Smith at Woodbin ever had PVC sacs made. I don't know of anybody except PSC who actually makes the latex sacs now. Martin Smith did, but he passed away 2 years ago. Jonathan Steinburg had some made, but they didn't have carbon in them, so were tan. To the best of my knowledge, everybody else simply resells sacs made by PSC. Buy them in a big enough quantity, and you can mark the price up a bit.
Visit Main Street Pens
A full service pen shop providing professional, thoughtful pen repair....
Please contact us by email, and not PM for repair inquiries.
Well that's unfortunate. Been looking for something on the larger size of PVC for myself (But at best it seems I could just find #15 such as from Nishimura's Snorkel kits), as would like to use it in a hard rubber pen, and don't want to use silicone (surface tension issues, and gas permeability).
But I guess latex is still the standard way to go and it's still available ... for now.
With hard rubber pens, I use latex. I had a couple pens that had PVC sacs, but they were installed a number of years ago back when this was an approach to celluloid discoloration concerns. I pulled those because of the negative interactions PVC can have with vintage celluloid. I went to true silicone sacs in those pens. I've used all of these pens extensively and the latex is better from a functional standpoint than everything else I have tried.
The silicone is what I use in a couple pens where I don't want discoloration, but one thing I've noted with the silicone is the tendency to push ink into the cap, even when stored nib-up. It seems like a quantity of ink remains in the feed, and then gas permeation pushes what ink there is in the feed up into the nib and into the cap. I had one Sheaffer flat top section covered in ink because ink pushed out of a cap over the weekend (nib up still) and into the cap.
I've noticed several of the pens where I used Aurora black more than others, had stained nibs (dark red tinting that would not wash off) and had sacs to fail earlier than expected, and earlier than pens where I only was using Waterman or Pelikan Blue or Blue-Black. None of the sacs failed in short order, but I will say I was replacing the sacs that had Aurora Black in them a couple years sooner than the sacs that used Waterman or Pelikan inks.
A question to which I'd love to know the answer is whether modern latex sacs can cause the celluloid discoloration that the vintage sacs could cause when they would deteriorate. Bert Heiserman once told me he was skeptical that a modern latex sac would do the same as a vintage one because he thought something in the rubber formulation had changed since older times. I have no data to show whether that is true or not.
Modern would still do the same thing (but also some of the moderns will fail sooner because they are not made with carbon like they're used to to improves resistance and stability. especially when near metal parts).
The discoloration comes from the aging and off-gassing of the sac, even if it takes longer for it to start aging. Alkaline inks will accelerate this process.
And I can definitely concur with the surface tension annoyance of silicone sacs, already had it happen in two freshly re-sac'd pens (both size #15) sitting upright overnight with no change in temperature/etc. As you said the ink likes to hug and sit at top. I've noticed that doing a flushing with clear dish soap, then water, seemed to improve it somewhat, but not by much. Seems like the main solution is a thicker sac.
And yes, PVC sacs can definitely harm celluloid and celluloid acetate (soft plastic) pens, it attacks the plasticizer in the celluloid causing it to go soft and no longer solid, an irreversible process. Also can't use it with a grip/section that is made of celluloid such as visualated sections found in some pens, even if the bodies are plastics. Seems safest to use in pens that use a metal sac protector, and the connection is rubber or stable plastic.
One thing I've heard recently, but I cannot confirm if it's true or not is that silicone sacs will die sooner if left dry and uninked. For that reason there was a suggestion to keep the pen filled with distilled water to keep the life of the silicone sac long (which seems bizarre to me, because how do the sacs that sat on the shelf last as long as they do left dry?). But like I said, I haven't been able to confirm that.
Far as hard rubber pens, the only reason I would want to use something other than Latex, is to be able to use more ink choices that are typically alkaline. Other than that, seems like latex is still quite reliable.
Last edited by KBeezie; April 15th, 2020 at 02:20 PM.
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