Repairing a crack (plastic pen)

[kestrel]

Safety person here with many years of experience investigating accidents and, much more to the point, working to prevent them...

 

 

 

The precautions for using/handling these solvents involve appropriate ventilation with fresh air, handling the minimal amount of flammable solvent necessary, and ensuring that the usage is well away from ignition sources.

 

I'll try to keep some of the discussion as straightforward as possible, but it's a more complicated matter in a work environment. This is only a brief overview for the purpose of discussion, and it cannot address all conditions, locations, or solvents - this discussion is intended only as a starting point for anyone doing occasional home pen repairs with flammable organic solvents.

 

Ventilation is pretty straightforward and simple... until it isn't. Organic solvent vapours tend to be more dense than air, essentially "puddling" in the area where liquid spills occur. The areas close to liquid spills or the open mouths of containers have appreciable concentrations which do not disperse as quickly as one might expect, allowing for a person in the area to inhale those vapours. Working in a basement corner, a small closed "crafts room", or some other place without ventilation is a poor idea. As a rule of thumb, people using these solvents should ensure that there is a substantial fresh air make-up to the pen repair work area. In a workplace, this would have to be done under a designed vent system to the outdoors.

 

Depending on the specific solvent being used, there can be acute or chronic effects. Acute effects are (relatively) quick and can include (but are not limited to) lightheadedness, fainting, even fatality. Chronic effects are longer term, and include teratogenicity, cancer, birth defects, etc. The casual pen repairer at home shouldn't have chronic effects, unless the person starts to do multiple repairs in sequence over time, which is a larger issue than fixing one or two pens.

 

While users can obtain respirators with the correct organic solvent cartridges, this is a long second choice to working with correct ventilation. Where someone would be performing this effort in a workplace on an ongoing basis with these solvents, testing of the area solvent vapour concentrations would be required, along with respirator fit-tests if that option were being considered. Important note - the dust masks and cheap respirators from the local hardware shop don't meet the requirements for a workplace organic solvent respirator. Anyone who is going to start doing this in a work environment needs a much larger assessment than we're going to discuss in this thread, which includes some stringent government requirements considering acute and chronic effects from the solvents, ventilation assessments for the engineered controls, and the list goes on at some length from there.

 

The average person who does a single pen repair with some decent fresh air ventilation shouldn't have large scale deleterious effects, unless...

 

...The home pen-repairer spills the flammable solvent in a sizable mess in the area where work is being conducted..

 

Solvents like MEK (methyl ethyl ketone) and acetone are highly flammable. They're not just easily flammable, but extremely so, vaporising and igniting far more readily than most people understand because of the intrinsic chemical properties of the materials. Flash fires move far more quickly than a person can run, engulfing them and burning them. Worse, a relatively small spill can quickly form sufficient vapour for a vapour-phase explosion, igniting from even from a light switch being tripped. MEK and acetone can explode far more easily than natural gas (methane) and with more explosive impact.

 

One shouldn't have to mention it, but then, accident histories show it is necessary to say it, no smoking, no open flames, no electrical heaters, and so forth should be in the room where pen repair with organic solvents is being performed.

 

Again, using these solvents in a workplace is a much complicated discussion than we're going to address in this thread, but, like the potential for acute and chronic exposures noted above, there are a plethora of well-founded government rules intended to protect people from being crispy-fried or exploded through correct management of the storage, distribution and use of flammable liquids. Control of ignition sources in workplaces becomes a subject in and of itself.

 

One of the best controls is only using/handling a minimal volume of flammable solvent. The average person doing a single pen repair should decant the solvent outside into a much smaller container for their work, which will minimise the potential for fire and/or explosion. How small ? Well, ponder that the putative home-pen-repair-person will be fixing a crack on one pen, so think about a thimble or two's volume, not a cup-full or more ! There is no good reason for the home pen-repair person to be handling/using organic solvents in bulk quantities indoors.

 

For those folks who comment that people use these solvents all of the time, and they haven't personally had an accident or seen one, I'll comment,

 

The plural of anecdote isn't data.

 

A quick check of newspapers and other media will show accident after accident, some terribly tragic, and in many of those cases there will be a comment, "We never thought that this would happen to us/him/her."

 

A few reasonable precautions for the person fixing one or two pens along with some care in their work should suffice to protect them against chemical exposure and fire/explosion hazards.

 

 

 

 

John P.

 

 

Take the warnings on the MEK can VERY, VERY seriously. Please. That stuff will make you see Jesus.

 

Bruce in Ocala, Fl

Former safety inspector/investigator speaking. Both the quoted posts above are worth rereading and heeding before handling MEK. The MSDS is full of all kinds of nasty words, many of them variations on "toxic," with possible severe Central Nervous System damage. CNS = Brain and spinal cord. It can be absorbed through the skin, the eyes, mucous membranes in the mouth and nose, and the lungs. The vapors make natural gas look inert in comparison. Be very, very careful with this stuff.

Link to MSDS for MEK: http://www.sciencelab.com/msds.php?msdsId=9927358

 

Ron's comments on crack repair are also worth heeding. Ron "restored to life" a Conklin Halloween I sent him a couple of years ago for major crack repairs. He told me it would take a long time to do the work and he was right but seeing the results justified the approach.

[inkstainedruth]

Okay. I talked to my friend the chemist over the weekend and was fairly amused by what she said she found when she started to research the subject:

1) FPN (possibly this thread even)

2) FPGeeks

3) non pen-related sites that said "Vintage celluloid? Talk to the pen people...."

Seriously though, she also sent me email saying that old-style nail polish remover (acetone) will work -- *not* the newer type; and that Testor's 3502 model glue is a mix of acetone and MEK.

On another thread, there was mention of something that I think was called "nitrate doper" which was celluloid in a liquid form (available -- at least when the post was made, at hobby shops catering to people who fly model airplanes). Anyone have experience with it?

Additionally, my husband is now curious about celluloid as well (some friends have put together a 3D printer). He asked me if anyone had contacted the folks who restore old movies, since those are shot on celluloid film stock. Anyone know offhand if it is the same formulation as what is used for pens? (Boy, if high school chemistry had been this interesting I might have paid more attention....)

Ruth Morrisson aka inkstainedruth

 

edited for typos

Edited May 13, 2014 by inkstainedruth

[Ron Z]

Nothing new there. Acetone will work on celluloid, but I don't use it. The reason is that it frequently causes the celluloid to bubble, which can be very difficult to remove or blend. MEK is much better with less of a tendency to cause bubbles - but it's more toxic. Then there's the solvent that I use which is better than that - but you have to have a Federal EIN to buy it - and it's quite hazardous.

 

For other plastics like Sheaffers, you want something containing methylene chloride - that's been said many times. Acetone doesn't work very well if at all with some plastics.

[FarmBoy]

Why do we not mention the solvent that some people use?

[pajaro]

To repair a crack whenever possible I buy a new part. The junk drawer fills up.

[white_lotus]

Presuming the pen isn't rare or expensive enough that you would be able/willing to buy another part.