Conklin Crescents

[Uncial]

Does anyone know the sac size that should be used in the 2n and 3n crescent models? I'm asking because I've swapped out two rather large and long sacs for size 16's trimmed from their standard size by about half an inch (to 2 inches roughly in length). It was to stop burping and leaking and seems to have worked but it is a very tight fit over the nipple. I wanted to check that I'm not stressing the nipple or courting a future unforeseen danger.

[JakobS]

Does this help at all? Pen Sac Company's sac sizes for Conklin pens

Edited January 12, 2018 by JakobS

[Eccles]

I'm unsure where to put this question and this seems as good a place as any, especially with Ron Zorn as moderator.

 

My wife's Mark Twain suffered a filler failure and I sent it for repair. The repairer says the sac appears to have 'melted' and believes it to be ink-related.

 

She normally uses Noodlers Ottoman Rose, but last fill was Diamine Shimmer-tastic Red Lustrre. I rinse her pens out thoroughly between every fill because they sit for a while awaiting their turn in the rotation.

 

Are there any known ink incompatibilities with Conklin sacs? It's not a cheap ink to discard, but obviously it's cheaper than new sacs every whenever.

 

Thanks for the advice.

 

Glenn.

[Eccles]

This is probably the better thread, and there are still no definite answers.

https://www.fountainpennetwork.com/forum/topic/304024-inks-that-eat-sacs/page-1

My repairer blames the Noodlers, based on his own experience.

Glenn.

[hari317]

Eccles, why not ask the repairman to install a PVC or a silicone sac as appropriate fir the material of the body of the pen. Then you can use any ink you like and not bother about the sac.

[Eccles]

Eccles, why not ask the repairman to install a PVC or a silicone sac as appropriate fir the material of the body of the pen. Then you can use any ink you like and not bother about the sac.

 

An interesting question, followed immediately by "Why did I not think of that? D'oh!"

 

The work is done now, so I'm too late, but I sure as heck will bear it in mind should the need arise again. I have 3 Mark Twains of my own, so a total of 4 in the house (when they're not away for repair!)

 

One comment by the repairer was that the filling system is very poor, unlike the early crescent fillers. The filler depends entirely on the sac filling and pushing it back into its rest position, which explains why it takes so flaming long to do so. He's invented a simple modification to improve it and is currently testing it out before sending it back.

 

His contact details are below should anyone wish to enquire direct.

PO Box 177, Berwick, Vic 3806, Australia.

Tel Intl +61 407 377 160

pensmith@pensmith.com.au

 

Thanks for the thoughtful suggestion.

Glenn.

Edited January 15, 2018 by Eccles

[Uncial]

Does this help at all? Pen Sac Company's sac sizes for Conklin pens

 

 

I'm looking at that and wondering if there are size differences between the EU and the States because a 22 size sac for an Endura would be enormous! Maybe those sizes refer to length rather than the width of the opening?

[Glenn Atkins]

Width.

[Uncial]

But then the 22 would be far too big. I'm confused, because not even a thick layer of shellac is going to hold a 22 in position. An 18 is a snug fit, but a 22 would just slide straight off.

[Ron Z]

Two comments - coming to the discussion late.....

 

We have seen latex sacs failing rather quickly with both Noodlers, and red inks. More precisely, with the dye saturated inks, and red of any brand. Both seem to require a higher level of maintenance to keep the pen from clogging. I would suggest that a PVC sac would be a good option if she is using Noodlers and an ink that contains red.

 

All three sac types have their advantages and weaknesses. Let me point you to an article where I discuss this at length. It may help you decide what type of sac to use.

 

Sac size. Some tend to go with whatever sac fits in the barrel. You can often get away with that since the barrel ID and sac nipple size seem to go together. OTOH, using a fractional dial caliper can't hurt, and will give you a good indication which size to use. Sacs are graduated in 64ths of an inch, so a #20 is 20/64. Note that is the OD, but if you measure 20/64, it will be a good fit on the sac nipple. General makes a plastic caliper that has the dial in both thousandths and 64ths of an inch. I have two, and use them.

 

If an 18 is too small, and a 22 is too big, use a 20.

[DasKaltblut]

So does anyone know what the sac material is for the latest batch of demonstrators? It can't be latex because it is clear, and it seems to be attached with an o-ring? I'm curious if it is PVC or silicone, as I decide what ink to use.

Edited January 18, 2018 by DasKaltblut

[Ron Z]

It won't matter what ink you use with either silicone or PVC. PVC has a harder feel to it than silicone, while silicone is stretchier.

[DasKaltblut]

Thanks Ron. Is there a difference in staining between PVC and silicone?

[Ron Z]

Thanks Ron. Is there a difference in staining between PVC and silicone?

 

There is, both in the chemical properties of the material, and the way that they work. You may find this article to be helpful.

[DasKaltblut]

The article doesn't say if silicone sacs will stain or not, just that PVC does.

[Ron Z]

I think either type of sac can stain. It just depends on the ink. Inks like Pelikan 4001 inks and Waterman won't stain a sac. The heavily dye saturated inks like Noodlers and Private Reserve will certainly stain PVC. I quit using the silicone sacs because of the gas permeability issue. I can't tell my clients how to use their pens, and if there is the possibility of oozing, I can't use them unless I want a bunch of warranty returns.

[Uncial]

In case anyone is reading this thread in years to come I thought I would put down my findings.

 

The No. 16 sac works for both the 3NL and 4NL Conklin Crescent models. It's a very tight fit around the nipple at the section. The No. 18 will not work because when you try to put the section back into the barrel, even with chalk the sac edge will catch on the join and be prone to further stretching and rips/cracks.

 

The No. 18 will work for the 2NL model and create a snug fit at the join of the barrel and section. I thought the size 16 would work for it, but it is too narrow a sac to be depressed by the bar to draw ink and doesn't create enough of a vacuum to pull ink into the sac. I donut have callipers, but I suspect there must be a difference in girth for the 2NL but it doesn't look that way to the eye.

 

In all instances the length of the sac is absolutely critical. I haven't quite worked out the optimum lengths but a long sac will result in burping and considerable leakage as tis leaves a large proportion of air in the sac with the ink and perhaps the weight of the volume of ink forces some out through the nib (?). Too short a sac and the pen won't draw enough ink. The difference in behaviour is a matter of about a centimetre and a half, so we aren't talking large variables here. Oh, and one last thing; the No. 16 sacs on the 3 and 4NL's can be fitted without shellac. Risky perhaps, but it is such a tight fit that there is no movement (I've been checking in paranoia). The No. 18 sac must be with shellac. It will come off. The amount of shellac and it's spread is important for the 2NL, because even a slight lack of coverage on the nipple will result in an air leak....messy!

 

I hope these findings are helpful. If there are any changes to this I will post them here.

[Tas]

My solution . . . an old Pilot cartridge

http://www.taskyprianou.com/fpn_conklin_crescent_filler_hack_.jpg

Edited January 30, 2018 by Tas

[Uncial]

That's um.. well.... an interesting solution. Not sure I'd want to try it out on my vintage Conklins' though.

[Tas]

That's um.. well.... an interesting solution. Not sure I'd want to try it out on my vintage Conklins' though.

 

Oh, apologies I thought it was the modern versions.

 

Lord no.