Hairline Crack In Plastic Section

[tmenyc]

To really close that crack, you'll need a solvent to weld it closed, which is what methyl etyl ketone (MEK) does for celluloid. CA is a glue, not a solvent. it holds pieces together, and works especially well on mating flat surfaces, but less well in small areas that take strain. For plastics, you generally need methylene chloride, which is available in varying strengths in high quality plastic fabrication applications and for scale modelers (like me...). Part of the issue with using these is that they usually also contain acetone, and scar plastic. Are you sure it's plastic? Is there a seam line? The different solvents work better with the plastic compounds for which they were made, so it's good to know what you're dealing with.

 

Tim

[Ron Z]

To reinforce what Tim said, CA also breaks down in the presence of heat and moisture - i.e. your pocket (especially under a sweater) and ink. It will fail. CA polymerizes with pressure, or the application of an activator. But unless you use a "hardened" CA, it won't hold long.

 

There can be tremendous stress on a section because a nib is a wedge, held in place by the pressure created by the wedge. The same pressure that split the section in the first place will cause it to crack again unless you bore out the section then make and install a bushing that will distribute the pressure around the crack.

[praxim]

It may be that further research will show that my conclusion below is incorrect. That will be fine by me; my intention is to advance our knowledge either by finding something new or by ruling things out. Firstly, a couple of perspectives.

Optimal repair of a cracked section. The best method to me is exactly as Ron says earlier, a custom bushing (perhaps sleeving in some cases). This requires both expertise and particular equipment.

Other people’s shoes. A professional repairer needs to allow for unknown use or abuse of the pen, yet will be considered responsible for problems which arise. An individual repairing for themselves both knows their usage (care and attention) and has responsibility for their own work, so can afford to test new options on themselves (give or take the cost of a destroyed pen ).

Now, some investigation and comments on issues which have been raised in other threads as well as this.

Wedge force is an issue which applies for any glue and leans on bond strength. If a glue (for example, a CA) has adequate bond strength then that is the end of that part of the question. If it does not, then likewise. As stated in my first caveat, sleeving is the best repair method against this problem but few do it or should need to.

Heat: This can not be a factor without asking how much? It seems common CA glues handle up to 60°C with 100% bond strength. I have data sheets on two listed for for operation at 80°C and it seems 100-150°C is needed to soften CA entirely. You do not get that hot. In fact unless you step into a hotter space and start suffering dangerous heat stress then the highest temperature the pen will ever reach while it is in your pocket is your body heat of 37°C (probably lower) and never 50+. If you leave your pens in a car in the sun then you will have other problems anyway.

Moisture: This was the most interesting one, where it becomes obvious that CA is a generic term, not a single formulation nor with uniform characteristics. I started on the Wikipedia page on cyanoacrylates, where the text contradicts itself on the subject within a single paragraph, so I turned to manufacturer data. Here are some links to glue selection, use of this one in an aquarium, and dishwasher-safe repair (see data sheet). I do not store my pens in an aquarium nor put them through the dishwasher.

My conclusion is that generic advice against using CA glues for repair of a pen section relates to generic CAs or to products from years past. It is perfectly possible to use a CA for such a task most effectively; just buy the right one.

(and check the use-by date)

[Ron Z]

I agree that one can do as they wish with their own pens. There are however some who repair others pens who are not nearly so careful and use CA indiscriminately... and then sell the pen as "restored." Hence my consistent, persistent advice not to use it. I get to see the results.

 

My experience with CA glues has been less than optimal, and it tends to let go at the most inconvenient times. Given the number of times that people have asked if they can use "hydrogenated yak squeeze"* to a] seal their pen or b] lubricate some part, I question whether the average amateur will do the research that you have to buy the right stuff but will buy whatever they find at the dollar store or Harbor Freight. I also hate doing a repair again for any reason if it could be avoided, even with my own pens.

 

 

*Bruce Barge coined the term, and it is worth continued use given that some things suggested are not that much different.

[Chouffleur]

I agree that one can do as they wish with their own pens. There are however some who repair others pens who are not nearly so careful and use CA indiscriminately... and then sell the pen as "restored." Hence my consistent, persistent advice not to use it. I get to see the results.

 

My experience with CA glues has been less than optimal, and it tends to let go at the most inconvenient times. Given the number of times that people have asked if they can use "hydrogenated yak squeeze"* to a] seal their pen or b] lubricate some part, I question whether the average amateur will do the research that you have to buy the right stuff but will buy whatever they find at the dollar store or Harbor Freight. I also hate doing a repair again for any reason if it could be avoided, even with my own pens.

 

 

*Bruce Barge coined the term, and it is worth continued use given that some things suggested are not that much different.

It's important to note that, "No yaks were harmed in the writing of this forum reply."

[praxim]

... I question whether the average amateur will do the research that you have to buy the right stuff but will buy whatever they find at the dollar store or Harbor Freight.

 

Agreed. I was careful about the recommended glues.

 

In mid-year I experimentally repaired a cracked BCHR section with what I considered a suitable CA, although not one of the two extreme types I named earlier. If, when or should it fail, I will faithfully report this to the forum. I did not mention it directly at the time because then I was less confident it could prove effective, but there was no clearly recommended alternative I found here. I did see a CA glue recommended by one poster but research showed it was more for metals and with no special moisture characteristics.

 

Incidentally, while I was on the Henkel site I noted that the glue I mentioned above is part of their retail line, (those from BSI are in hobby shops). Henkel also have industrial cyanoacrylates used in automotive repair including on rubber body seals exposed to significant solar heat and to drenching water as well as to the usual pollutants of the roads.

 

I think it useful to know that investing in glue selection will discover something which combines desired characteristics of efficacy and ease of use. It seems one of the key parameters is to look for EN204-D3 or at least -D2, a durability rating which includes water testing.

[LizEF]

Moisture: This was the most interesting one, where it becomes obvious that CA is a generic term, not a single formulation nor with uniform characteristics. I started on the Wikipedia page on cyanoacrylates, where the text contradicts itself on the subject within a single paragraph, so I turned to manufacturer data. Here are some links to glue selection, use of this one in an aquarium, and dishwasher-safe repair (see data sheet). I do not store my pens in an aquarium nor put them through the dishwasher.

 

And yet, the (M)SDS for that says:

 

"Hazardous reactions: Rapid exothermic polymerization will occur in the presence of water, amines, alkalis and alcohols.

...

Incompatible materials: Water, amines, alkalis and alcohols"

 

Hmm. Now I can't claim to understand that from a scientific point of view, but it doesn't look to be OK with water* - nor do the other glues they say are compatible with plastic (they all say the same thing about "polymerization"). The dictionary didn't really help me, and I don't want to be a chemist - though I know some. Maybe I'll ask one.

 

* I guess time will tell. Glue from these guys is sealing the crack in the section of my Waterman Laureat, and has been working since ~May.

[praxim]

Water (moisture in the materials or atmosphere suffices) is what sets CA. Hence "rapid exothermic polymerisation" means it sets, and releases a little heat.

[LizEF]

Water (moisture in the materials or atmosphere suffices) is what sets CA. Hence "rapid exothermic polymerisation" means it sets, and releases a little heat.

 

Thanks, Praxim - so good news instead of bad - hooray!

[sandy101]

[Ink Stained Wretch]

Can anyone state categorically what exact kind of plastic the section of a Waterman Phileas fountain pen is made of? And what would be best to fix a hairline crack in one? I'd used the pen, a broad nib, for years, and then I found my hand full of ink. It was a nice pen, and I'd like to use it again.

 

I had wondered about solvent welding it, and I'd wondered if maybe epoxy would be better to fill in the hairline crack, if possible. Maybe filling in the crack would be better than welding the section closed again. I'm thinking that maybe something filling in the crack rather than forcing it back together again might relieve whatever pressure had forced the crack into existence in the first place.

 

Anyone have any knowledgeable advice on this?