I am getting back to the model rr after some time out of the field. My question is about adhesives: I understand the uses of two main types, plastic cements and CA adhesives. These were described recently in the new book on structures published by the MR people. But what about other adhesives that used to be mentioned: epoxy glues, goo formulations, or a urethane adhesive like Gorilla glue? There probably others I have missed. Do these find general use or is the field now dominated by the plastic cements and the CA glues?
A lot depends on what you're trying to stick together. Most common plastics, the plastic cements work well with a good fit. Metal to plastic or plastic to wood, plastic to plastic, CA works. Woodland Scenics sells several different adhesives, I've had very good luck using their Scenic Glue for wood structures. Metal detail parts to cast zinc body shells, CA is good. Haven't tried many others, haven't had to. Epoxy is still as good as it ever was, just a little harder to work with than some others.
CA also works well for putting stripped out drivers back on their axles, if anyone else beside me is dumb enough to be trying to repair some of the junk I am.
Have you ever had problems with CA not holding up in high-moisture environments, especially when you get away from plastics where the joint is more like a weld than a glue bond?
a) CA doesn't "weld" plastics. Solvent cements do that.
b) CA sets by a chemical reaction. I can't recall whether the moisture in the air kicks the reaction, or whether it's part of the reaction. But either way, in a high humidity environment, the setting may well start too soon, so that the cement is already partly set when you apply it to the parts. This will of course make for a weak joint.
c) if you're using the watery CA, let capillary action draw it into the joint.
PS: It may be that mold release agent is interfering with the CA bond to plastic. Anybody know whether that's so?
The only problem I've ever had with CA is getting something off that's not where I wanted it. Moisture, from my experience, doesn't bother it at all. I've really had no problems with anything I've used it on, other than sometimes having it grab just when something is exactly where I didn't want it. My buildings are all scratched, wood with plastic door and window castings, no problems there, although no problems with the white glues either, once they're cured for a couple of days, normal humidity isn't going to bother them for a long time.
CA doesn't weld plastics like the solvent cements, it's the same bonding as for everything else. BUT. Using CA on wood>plastic, you run into humidity expansion of the wood, which could potentially cause a problem as CA has exactly zero flexibility once it cures.
There are applications for each type of glue/cement, but for MRR use, CA can be a good choice, although not always universal. For my structures, I've gone mostly to Woodland Scenics "Scenic glue", it grabs on fast enough yet gives a little working time to correct errors.
The local Dollar Tree store has been stocking Pacer Super Glue, three
2gm tubes for a buck. I've found this practical, having most of a bottle of Zap going to honey before I use it can get pretty expensive. The smaller tube, I generally get most of it used before it plugs so bad it's useless. Epoxy for high strength apps, also good for filling unwanted holes or just building something up to carve and file to shape.
I'm currently working on putting Cary boiler conversions on an IHC and Rivarosi pair of pacifics, using mostly CA, but where repairing damage, I got the chassis for el zip, using whatever seems to be called for. There is no one universal cement for all purposes, small amounts of a few different ones give some flexibility of choices.
Phenoseal. Comes in tubes for the caulking gun. Found at Home Depot or hardware stores. Dries clear and will bond flex track ties down to Model Engineering plastic viaducts.
Bathtub caulk. Excellent for securing ballast weights inside boxcars. Dries to a rubbery material and doesn't let go of the weight even if the car is dropped.
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