Repairing holes in plastic FPs--practicing

[che63]

Hi Folks,

 

I hope everyone is having a relaxing Sunday.  I've been doing some minor FP restoration over the last couple years.  I am now experimenting with more significant repairs leading up to repairing a MB 22 with a crack in the cap and a MB 24 with a burn hole.  I'm hoping to get feedback from you all on how to improve my technique. I'm practicing on a couple of junkers made of some sort of plastic.  The black one is an eversharp and the red one is unbranded.  They look to me like they are from the 60-70s.

 

The process i used for both pens (the pics from left to right show the steps i used).

1. gouged both pens using a dremel.

2. filled holes with an inexpensive CA glue.  let set overnight.

3. sanded with 800 grit paper.

4. repeated steps 2-3, three more times because each time the dried glue cratered leaving a void in the middle.

5. used yellow then blue dialux compound on a buffing wheel.

 

From arms length the repairs didn't look half bad and the pens came out glossy.  Upon closer inspection there were a few pin holes.  also, both pens had dark shadowing where the CA glue was applied; it's more noticeable on the red pen.  the black pen also had a weird halo effect surrounding the darker area; it's not very noticeable without magnification.

 

On my next go round I'll be using the Locktite ultra gel control that has been mentioned on this site and i'm also going to experiment with an accelerator (by the way, i have an outstanding post on using accelerators that no one has replied to yet, so if you have information about that topic, i'd love to hear it).  I'm also going to take on a crack, which should be interesting.

 

Any advice on making the repair better (less noticeable) overall.  Is there any way to get less cratering, which would mean having to put fewer coats of glue and sand less.  I appreciate any advice you might have.  Thank you.  Arron.

 

 

 

[enuhski]

Looking forward to updates on this! My go to nibmiester has tried to repair a MB generation of mine with a tiny crack in the section. He used some kind of clear glue and sealant but sadly the pen continued to leak. I hope you can perfect your technique. Good luck!

[dipper]

Cyanoacrylate glue ("Superglue") in its normal form, straight out of the bottle or tube, is not an ideal material for hole filling. But there are some tricks we can use that modify its behaviour.

 

The glue hardens by spontaneously linking its molecules together into long chains, not by evaporation of a solvent. That polymerization process kicks-in when conditions are just right = in narrow gaps, with no air contact, with a suitable solid surface each side of the gap, and with traces of water vapour present. But sometimes the "curing" process kicks off inside a part used bottle, sending that bottle to the waste bin.

 

Some solid surfaces help trigger the curing process, such as certain metals, wood, leather, paper and, unfortunately, skin.

 

Some other solid surfaces inhibit the curing process. Certain plastics for instance. I have superglued plastic items, clamped tightly, left for hours to cure, only to find on removing the clamps that the glue in the joints is still liquid. Dealing with such surfaces is what accelerators are for. A light spray of accelerant on the solid surface promotes triggering the curing process. When triggered at one point the self-linking of molecules is itself a stimulant for more molecules, so the curing process propogates through the glue patch.

Personally, I never bother with accelerant. If superglue refuses to cure on some surface then I just breathe gently over the (cold) surface to add a trace of moisture, then apply superglue.

 

The trick to using superglue as a gap-filler is to add powder. When superglue is absorbed into a fine powder that can trigger rapid curing, bonding the powder particles into a rigid concrete material. The process can be so fast that it not feasible to mix powder and glue together and then apply the mixture.

A well known method for filling the grooves in a guitar "nut" if worn, or accidentally cut too deep, is to place a little heap of dry baking soda powder into the groove, then apply a drop of low viscosity superglue on top. In seconds the glue and powder cure to a solid that can then be sanded and the groove recut. There are youtube videos, of course.

 

If no powder is used then gap filling relies on the curing process propogating through the open blob of glue. It can work, but is slow and perhaps unreliable due to shrinkage of the mass during curing.

 

I often scrape coloured powders from artist's pastels to colour epoxy resins, epoxy putty, and low temperature melt plastic ("Polymorph" or "PCL"). Have never tried that with superglue, but could be worth an experiment, applied by the same method as the guitar-nut baking soda repair.

 

 

[che63]

thanks for that information.  i'm not having great results using the CA.  i tried some using a homemade accelerant, ipa and baking soda, and the results were worse--it turned out white which couldn't be buffed out.  you mention epoxy resin.  i've been reading about uv resin but i can't find any information about how the process would work for repairing pens.  do you know of any resources for that?

[pgomme]

3 hours ago, che63 said:

i tried some using a homemade accelerant, ipa and baking soda, and the results were worsep

ipa =India Pale Ale?

 

Did you drink it while waiting 🤔

[che63]

I'm getting to the end of my experiment.  I've received very little feedback on the process i've used thus far, which is disappointing but hopefully this thread will be of some use to others along this same learning curve.  In this next go 'round i used the more expensive Locktite ultra control gel.  i made a divot in both the red and black plastic pen barrels.  on the red one i put a little homemade accelerant (baking soda and ipa) down first then applied the CA.  the CA did not harden for some time, maybe 30 minutes.  It cratered just like when i added no accelerant.

 

on the black pen i put accelerant on the bottom but also sprayed the entire repair site after adding the CA.  It hardened right away, but left a white crystalized bumpy mess (maybe from the baking soda).  i sanded this one with 800 grit until it was very smooth to the touch.  You can see in the third picture, i never could sand out the white stuff although it did get smaller.

 

So my conclusion, based on this limited experiment by a novice, is that the CA repair was far from perfect.  At arms length the black pen repair was decent, the red pen repair was less so.  Upon close inspection, neither worked great.  if no alternative method of repair, the CA repair would be better than not making the repair, i.e., it did improve the damaged area.  At this point i wouldn't feel comfortable using my CA method on my two vintage MB pens (setting aside the "precious resin" issue).

 

another observation, for those not on the fpn FB page (i'm still trying to figure out the difference between this forum and that page), several people on the FB page suggested that CA is not the proper medium for pen repair (filling in divots).  They recommended using a uv resin or epoxy; for their durability, quality, and ease of color matching.  Unfortunately, i've found no resource online (including a search of this forum, but maybe i missed it) for how those media would be applied in the context of pen repair.  

 

If anyone has comments on the experiment with CA or on epoxies or uv resins i'd love to hear them, before i start down those (epoxy/resin) rabbit holes. Maybe someone who uses epoxy or uv resin for filling holes could shoot a youtube video to help the rest of the community  .  Hope you all have a nice weekend and have the opportunity to work on some fountain pens.   

 

 

[dipper]

My favourite gap/hole filler is milliput epoxy putty.

 

The milliput product is made in various colours. Each colour indicates the fineness of the material. I now use only the "superfine" grade, that happens to be color-coded white.

Being white it can be coloured by mixing with dry coloured artist's pigment powders.

Can be mixed with pigments to give any pastel colour, but results are never strong deep colours.

My most recent job was filling a hole in an ancient terracotta pantile from the roof of an old outbuilding. I managed an acceptable pinkish colour. Smoothed by fingers and water, in the same way as shown in the video above. Often though I overfill a hole in wood or metal and then sand smooth afterwards.

 

For a transparent filler (well, nearly transparent) I use 24hr Araldite. This has the consistency of stiff treacle. Mix in equal parts, apply to slightly overfill the hole, cover with a strip of clear adhesive tape, ensuring no air bubbles trapped, and leave in a warm place to harden. When fully cured peel off the tape and sand smooth, flush with the surface being filled.

The cured Araldite epoxy is transparent with a yellowish tint.

 

Similar two part epoxies are available that claim to be "Glass-Clear".  I have not tried any of those.