Loctite 480 as filler in celluloid...

[Nightjar]

I'm getting seemingly very good results with Loctite 480 for repairing major cosmetic blemishes on (black) celluloid pens: see before/after below, the "after" is not a very good photo, but the repair is visually undetectable, or pretty close. Other parts of this pen had severe scratching (like it had sat at the bottom of a toolbox or something): Loctite 480 worked well for that too. And it seems to have worked to fill/bond a cap-lip crack (deliberately filled open, about 0.5mm gap; rather than trying to bond it tight closed, which would inevitably break again under tension).

 

My question is whether the fix is likely to be durable over years/decades. Or whether there's a risk of chemical damage to the celluloid? Or the two materials might (?) age differently, so that the repair gradually becomes visible. I guess these things may not be known yet!

 

 

 

[Ron Z]

I wouldn't, and don't.  Though some use cyanoacrylates as a filler, it isn't intended for that.  It can take time for reactions to chemicals applied to celluloid to show up.  It may be months or a couple of years before you see it, but then it's too late.   Once celluloid decay starts, there is no way to stop or reverse it.

 

 Loctite says that there can be some cracking with some plastics, though the data does not mention celluloid.  I would be surprised if it did since celluloid is rarely used today.  The technical data sheet can be found here.

[Nightjar]

Thank you @Ron Z, appreciated!

 

Just to be clear: is that because you've observed or read about some or all of the issues you indicate, actually happening I mean? Or is it simply abundance of caution? (Which I'm not knocking, abundance of caution is good: just different from actual observed issues.)

[Nightjar]

@Ron Z ChatGPT agrees with you, by the way, pointing to potential issues including shrinkage, increasing brittleness, and off-gassing. I suspect ChatGPT's view is based on abundance-of-caution "internet wisdom", not "hard science", but I certainly get that there's reasonable basis for abundance-of-caution, so I will look for an alternative 🙂 And meanwhile I'll watch to see whether any issues develop with the three pens I've repaired in this way...

[Ron Z]

Both really.  I've seen enough weird stuff with cyanoacrylates that I don't use it for much of anything.  Black celluloid is likely to be less vulnerable, but black and pearl, Sheaffer's marine green and red veined celluloid, and many of the Wahl Eversharp celluloids are known to be on the fragile side.  I'm very careful with what I use on them.  The other concern is that once a surface has been contaminated with CA adhesives,  I can't guarantee any repair using solvents.  I've tried, and the repair usually doesn't hold, or work well.  The last attempt was with the resin used in an Omas 360.  Areas that hadn't come in contact with the CA were fine, but areas that did, like the cracks that were the main reason for the repair developed a ton of bubbles, and I couldn't get rid of them,  You can't clean it off well either because the same solvent that dissolves and removes CA adhesives (acetone) also dissolves celluloid.

[Nightjar]

My second message crossed yours I think, but thank you, I really appreciate this expert advice, all noted!

[Nightjar]

And with apologies for asking too many questions: if anyone can suggest an alternative filler for celluloid (readily available, not fume-cupboard-toxic) that'd be really appreciated. I see multiple references to solvent-welding with acetone, but I can't find any mention of products for filling.

[Ron Z]

There aren't any outside of fume-cupboard-toxic.

[Nightjar]

🤣 that's simultaneously disappointing and liberating, simplifies my choice... cyanoacrylate it is then, with fingers crossed; well, that or no repair! Thank you Ron, really appreciate your reply.

[Ron Z]

You can dissolve celluloid in acetone or MEK.  MEK would be better because it evaporates more slowly.

[VacNut]

Just to confirm, you are certain the pens are celluloid?

 

It is common to slightly warm celluloid to loosen fitted parts, release fillers, to re-install cleaned parts. Does the filler material expand/soften/relax similar to celluloid?

 

I have not tried it, but I understand people mix self-made fine celluloid powder with MEK to infill cracks and gouges. The powder is commonly from a donor pen of the same color.

 

I am also told bite marks from nervous writers can be removed by heating the celluloid just below combustion temperature. I guess the celluloid slightly emulsifies (if that is the correct physical term) and returns to its past form? 
I am told it is a miraculous process, almost like it is self-healing…hallelujah!

[Ron Z]

Good question.  It might have been possible to lift the flaw out enough that with a little more work the flaw could have been blended and removed.  It depends on whether it's a ding, or whether the material was cut away.  I've made tooth marks disappear with out filling them.  Delicate work, and not recommended for an amateur.  There is a very  fine line between lifting out the damage and igniting the celluloid.

[VacNut]

Thx Ron, 

Sounds like one may have a good story to tell if the celluloid ignited!

Definitely need a reliable and precise heat source. A bit of practice on a junk pen may also help.

[Nightjar]

@VacNut I haven't heated the pen at any point, so can't comment on expansion, but it's an MT Swan 1060 (older model with flat top) so barrel and cap celluloid I think, and section hard rubber.

 

I may play around with acetone and scrap celluloid sometime, but will likely steer clear of MEK and, er, "heating to just below combustion temperature" 😱🤣

 

I don't know the reason for the pitting shown on my pen: maybe at some point it received a light splatter of some corrosive liquid, or was stored against a cloth that had traces of something corrosive on it. Just wild guesses!

 

 

[es9]

If you were to graph the risk-reward tradeoff for various cosmetic repairs, many would look like some version of the graph of enzyme function to human body temperature. You steadily make good progress, but then the return starts to diminish. And if you keep pressing on, you end up falling off a cliff. Learning when to stop can be almost as hard as learning a repair technique itself. It’s something I am constantly working on, and I have a few celluloid corpses hanging around as mementos mori. 

 

Not all pens can be made perfect. Sometimes the teeth marks seem to vanish like magic. Other times small remnants remain. Learning to enjoy—or at least accept—the imperfections is another dimension of the hobby. 

[Ron Z]

3 hours ago, VacNut said:

Sounds like one may have a good story to tell if the celluloid ignited!

 

Well, it's like this.  The first clue that you get that the celluloid is too hot is the puff of acrid smoke....  It may not make it to full flame, but you get a lot of smoke very fast, and it stinks!  

 

I did purposely light a celluloid section once - a damaged Vac Jr section.  You know how small they are.  I went outside taking my boss with me.  "Hey, John, you need to see this."  I held the section in a very long pair of tweezers with a lighter under it.  It sat there for a second or two and then violently burst into flame.   The flame was about a foot high and lasted for about 15 seconds, leaving behind a 1" or so long piece of ash.  I was like yep, NOPE, never going to use open flame on a pen.

[VacNut]

I have transported hundreds of pounds of celluloid vac parts for people over the years in my check-in luggage. The airlines worry about the 3-4 ounces of liquids in my carry-on. Good thing they have never checked on the flammability of the luggage.

It is up to each owner to decide the level of high polish on vintage pens. I noticed the repaired pen had a very high gloss polish. The loctite repairs may be more apparent on less polished pens.

[Nightjar]

Yes it was fairly high-gloss already, but with that area of deep pitting, and other areas with deep scratching (like from a coarse wire brush or something), and the cap lip crack. Where the scratching extends into the inscription, I haven't touched it. Nib lovely, though a bit broad for my taste.

[es9]

Keep in mind also that filling them with something other than dissolved celluloid will never look quite perfect. I did one once with black epoxy. The two materials didn’t look the same when polished, and they aged/wore in slightly different ways. 

[Nightjar]

On the first point, I must disagree, at least as regards my pen: I've just checked, my repairs are visually undetectable even in good light under Optivisor. On the second point: time will tell, and I certainly understand it might go pear-shaped 🙃