I just nabbed a Jade Lady Duofold off of eBay, and the colour is absolutely perfect. There are pen sacs in the proper size in latex rubber, but I am quite worried as to the detrimental effects of the sulfur in the rubber sacs on the celluloid. Is there a silicone sac in size 17 1/2 necked? Would a size 17 1/2 or 18 work?

Well, Woodbin has #16 and #18 silicone sacs. "Proper size" is kind of a matter of perspective. If you have to choose, certainly too small is better because the pen will be less likely to suffer from heat transfer from hand to barrel to sac kinds of problems (like flooding and dripping).

I'd go down a half size rather than up, especially if this pen would be a daily writer. I suppose it will be, or why put a sac in it at all, right?


Cheers,
Tom

If it were a straight 17, I would get a 16 without a doubt, but it's a 17 1/2 necked. Would having a significantly smaller sac hinder the button filling mechanism?

Do latex sacs radiate sulfur, or do they only release it when one lets it ossify?

I purchased the pen as a sort of parting present for a friend of mine (a Lady Duofold for a lady ), and I'm fairly sure that she would use it daily or at least enough to keep the sac from rotting. The only thing is, this is the nicest Jade Duofold I've seen on ebay in a long time, and I'd really hate for it to be ruined because of my stubbornness or her relegating it to a drawer.



Three cap bands, too. No chew marks on the blind cap, either.

A smaller sac wouldn't be a problem for the pressure bar. Silicone is a little more firm that rubber, but this won't be an issue if the innards are clean (no rust or corrosion).

I see that the Pen Sac Company suggests using a 17 1/2" necked sac on a Lady Duofold, but if it were me, I wouldn't hesitate dropping a 16 in it. There's only 1/64" difference in the outer diameters. Likewise, there's only 1/128" difference between a 17 1/2 and an 18. If you're determined to use a silicone sac, you could get both sizes and use the one that fits best. You'll find a use for the other one eventually.

BTW, nice little pen. I'm sure your lady friend will enjoy it.


Cheers,
Tom

I believe that Binder's website states that you should not use necked sacs, or at least that he doesn't use necked sacs. They are necked to increase the ink capacity, but have a tendency to burp up ink because they are close to the outer wall and suffer from heat transfer. As to size, a straight 17 would prolly be ok, but if you can't get that then I'd also say just get a 16, it should be ok. I don't know if they radiate sulfur or just do that when they ossify, thats a good question. I'd guess the former, otherwise people on here would say "you don't need a silicon sac, just don't let the sac rot" or something like that.

I haven't used necked sacs in the nearly 20 years that I've been repairing pens. I rarely see them when I open a pen for repair. (you'd be surprised how many times I pull out an intact, rock solid sac). I rarely see, actually can't remember ever seeing a necked, tapered sac in a Skyline either.

re. the silicone sacs. As mentioned in a previous post, Martin is making silicone sacs that have thinner walls, that put less stress on the filling system, whether button or lever. The trade off is that they are not as elastic, so don't stretch like the latex sacs do when you put them on a section. You may have to actually go UP a size. A trick to getting them on is to slip them over the end of a pair of needle nose pliers and then stretch them a bit before slipping them onto the nipple. Clean the end with alcohol to remove the mold release, and use a good quality shellac.

Okay, I'll nab a 16 and an 18 off of Tryphon. Thanks for the input.

So how do the current silicone sacs compare to the latex sacs overall? Is silicone a better choice now, since they don't ossify, or will they tear at some point?

There's no pat answer to your question. I still use latex sacs for most repairs because I find that their performance in general is better, and I've had fewer pens with latex sacs come back with problems. The silicone is best for pens that are likely to discolor. I also use them if I have to replace the sac on a 51 aerometric.

The silicone sacs were too stiff before, now I find them to be a bit too floppy. They don't seem to fill quite as well. They also don't stretch as much as they used to, so it's harder to fit them onto the section.

Nevermind.

oh! I knew I wasn't the only one complaining about the newer "thinwall" silicone sacs from martin @ woodbin. I had to send a whole batch back because I had 10 pens coming back in one week. All of them had flow problems and the sac would not return to the fully "inflated" position when refilling. It drawed ink to a certain point where the sac sould not suck any heavier fluid than air. You feel it unchoking when you raise the pen from the inkwell. Replaced that batch with "the thickest silicone sacs you can find me" (Martin is one fine gentleman and replaced them sacs with no questions, delays or reshipping charges, mind you! ) and they work fine.

I found one of these recently, though the barrel is discolored from ink. Same model by the look of it, three cap rings and all. Timely info for me too- thanks!

Aaron

Got the silicone sacs from Giovanni today. The 18 was a bit too big - the section wouldn't fit in the barrel because the sac was so thick. The 16 was just perfect.

Also, I must say that Giovanni's XP Polish is amazing. Got a free sample of it, and it works wonders on all sorts of colours (not hard rubber, though, I think that may be dangerous).