Regluing plastic building walls

Discussion in 'FAQs' started by jtbterri, Jun 12, 2005.

  1. jtbterri

    jtbterri Member

    I tried this problem over on Trains but got lost in the pile with no real answer.

    I am assembling the Walther's REA Building kit(HO). When I initially glued the end pieces to one of the sides, I used a CA glue (Rhino Glue). In the course of moving the partially assembled model to another location, one of the ends snapped off.

    I decided that the next time I would use a plastic glue(Micro Weld) instead of CA, so I scrapped all of the residue from both sides of the joint, end and side, and began attempting to get them to bond together with the plastic glue. I wanted to go back to a plastic glue as the CA actually overfilled the joint and it was difficult to get a "seamless" look like you can with the plastic glues which actually "melt" the surface of the plastic parts giving a smoother, joint. Also a plastic cemented joint is more pliable than a CA one giving a little more flexibility in squaring up the walls.

    Sor far, I have tried regluing this joint at least four(4) times with no success. No matter how I apply the plastic glue it merely dries in the joint without bonding. I'm wondering if the problem is that once you've used CA on a plastic joint you can no longer ever use a plastic glue.

    I should have added at the start of this thread that I scrapped the joint clean of any CA residue with a xacto knife the first time I tried the Micro Weld and then each succeeding time after trying the Micro Weld. Also, I used Micro Weld to glue the other parts of this kit such as windows, doors, and the brace/filet between the walls without any problem.

    I think the problem has something to do with a chemical change, whether visible or not, on the plastic surface after the CA has been applied. The result is that the new surface resists penetration by the plastic glues, at least Micro Weld.

    Anyone else had/solved this problem??

  2. b28_82

    b28_82 Member

    I could be wrong but I don't believe there is any chemical change. I have had to take apart a bad gluing job where someone used superglue on a car kit and I had to file off all the parts of the superglue
    My regluing with plastic cement worked; but if I remember correctly, I had to use a different glue than the normal Testors or Testors equivalent. I have been using this stuff called Tenax7r. The way it works is you can put two pieces of plastic together (such as a corner to a building) and, with an applicator, run it along the seam of the two parts and it does the work itself. You gotta be quick though because this stuff dries real fast. Hopefully this solves your problem.

  3. ezdays

    ezdays Out AZ way

    Your problems seems to be unique. If you are able to sand the edges slighly to remove the super glue. Just about any plastic cement should work after that. About the only thing it shouldn't be able to stick to is Teflon. The thin, watery cement has to contact the plastic in order for it to melt it. The best way to use that is to hold the two pieces together, then touch the glue to the top at one spot. I use a small squeeze bottle with a long thin needle point on it, something I picked up years ago in a plastics supply house. Capillary action will pull the glue down the whole joint. The thicker plastic cement is the same thing, only in a thick base. It is designed to bridge gaps as well as giving you a longer working time. CA glue gets into the cracks and crevices, but shouldn't change the chemical composition of anything it touches. If you're still having problems, you might want to try an all-purpose glue that will work on ceramics as well I have a tube of "Welder heavy-duty Adhesive" that works on just about any surface. I think I got that at an Ace Hardware store.

    Good luck, let us know how you make out.
  4. Pitchwife

    Pitchwife Dreamer

    I'm not familiar with the glue that you are using, but I know that the ones with a low viscosity, in other words the thinner ones, require an exact fit between the two pieces because they won't "fill" any gaps. You might try a thicker glue that will fill in any small gaps left from your sanding and scraping.
  5. eightyeightfan1

    eightyeightfan1 Now I'm AMP'd

    Try wiping the area with a small amount of nail polish remover(Its what they say to use if you glue fingers to themselfs). Maybe a couple of washes with nail polish remover should remove the residue. Light sanding after with a fine grit sand paper will expose fresh plastic.
    Just a hint: Use CA only if your trying to glue two different types of plastic, such as ABS and styrene. Testors or Tenax should be good for Walthers kits.
    Hope this helps.
  6. Doc Holliday

    Doc Holliday Member

    Good idea, but make sure the nail polish remover contains acetone. I had a little "accident" with CA glue late one night and borrowed some of Mrs. Doc's remover. Turns out that since she wears acrylic nails, she uses a non-acetone variety of polish remover. It don't do squat to CA glue. :cry:
  7. engineshop

    engineshop Member

    Glues like MicroWeld dissolve plastic but are thinned down so much that it only will attack the top layer of a model kit. Since you used crazy glue, you sealed the plastic with a glue that is not effected by MicroWeld or similar. You would have to scrap it down until the layer is completely gone and maybe your corner pieces as well.
    Learned that in a wood shop class when a second time wood glue would stick anymore.

    Did you try to attach styrene pieces inside the wall and glue them together?
  8. jtbterri

    jtbterri Member


    First, thanks for all of the feedback. I now know why I like to post and follow theis forum over others.

    I took the advice about filing off the joints I had cemented with Rhino Glue (CA). I had previously scrapped them with a xacto knife and removed what I thought was all of the glue's residue. When I used a file I started seeing some white in the filings and realized that there was still a surface coating on the plastic, so I continued until I was getting just the reddish color of the base plastic. This also tended to "rough-up" the surface where the knife had left it relatively level.

    I have used Tenas7R very successfully in the past on other models, but had left the top off one night and bye-bye, all evaporated. Since the LHS in my area didn't have this brand, I switched to Micro Weld, as I have had good results with their other products, MicroSol and MicroSet. The Micro Weld worked well on this Walther's kit, at least up until now.

    Last evening, for the umpteenth time, I tried again. I followed Don's reccomendation
    I applied the Micro Weld to both sides with a brush at the lower part of the walls, pressed them together for several minutes to get the joint as seamless as possible and then clamped them together with weights. When I went back later in the evening, the parts were still solidly together where the glue had been applied. All looked well. This AM went out to inspect my efforts and again the walls had separated as if I hadn't even been there. Further more, the joint on both sides was shiny as if the glue just dried on the surface.

    I'm leary of using any acetone based solvent as my experience with a couple of other plastic kits and acetone was far from optimal. The acetone actually caused the plastic to bubble/blister rather than just melt, even with minute quantities.

    I've now changed the angle of the bevel between these pieces and may have to go back to the CA glue as it is thicker. I've tried the thick Testors Plastic cement but was not very impressed with my ability to get smooth joints. The thick plastic cement was difficult to get applied evenly enough. Also, cannoth get a styrene strip into this joint because of other parts, windows, doors, interfering.

    The other option is to refile the joints to get them to as close together as possible, and find a source for some Tenax7R to try again. Roland's comment about Micro Weld makes perfect sense to me at this point.

  9. jtbterri

    jtbterri Member

    Just checked again locally to see if I can find some Tenax7R but no luck. The nearest LHS reccomends a product called "Proweld" by "Ambroid"..Anybody used/heard of this??
  10. MasonJar

    MasonJar It's not rocket surgery

    George -

    At this point, you may want to give up on the original joint, and hold the walls together with a bit of styrene angle on th inside of he building. This will let you get the gkue of choice into contact with "fresh" plastic on the angle and the inside of the walls. I know you siad there is little room, but there is almost always some room.

    I have heard of Ambroid, but no experience with it.

  11. jtbterri

    jtbterri Member

    Success at last! The solution was a combination of tips posted above; cleaning of the joints, type of cement, and method of applying the cement.

    First off, I had originially scrapped both sides of the joint with an exacto knife thinking I'd removed all of the CA glue. Wrong. When I filed the joints after scrapping with the exacto, I still removed some white residue, which I assume was the glue. The filing also roughed up the joint which may or may not have helped.

    Next, I applied some nail polish remover, making sure it did contain some acetone. I used very little, just enough to leave a little red on the microbrush that I used as the applicator.

    I followed the suggestions and changed the plastic cement. I gave up on the Micro Weld. I tried to find some Tenax7R, (which I have used successfully but evaporated), locally but no luck. Then, on a business trip in LA I went to an old standby train store, discussed the problem and took them up on their suggestion of using Plastruct Bondene. It too is a plastic solvent type of cement for styrene and ABS. The active chemical agent is Dichloromethane.

    The final step was the actual bonding of the sides. I had tried placing one side flat and the other at a 90 degree angle vertically and flowing the cement into the joint horizontally. Didn't work for me. Couldn't get the pieces to bond over the entire length of the joint.

    I then tried standing both the sides up vertically at a 90 degree angle, and "spot welding" a small length near the top. When this had set up about 30 minutes, I took a syringe/needle and flowed the Bondene down the entire seam while holding it together. Success! Smooth joints and very much "together.

    Thanks again for the tips and advice.

  12. MasonJar

    MasonJar It's not rocket surgery


    Great news! Glad to hear the problem is solved. Thanks for sharing your results... :D


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