In using this gel to secure resin to plastic a question came to mind again about this stuff. Why is it that you are only supposed to apply it to one part? That stuff is still essentially getting on the mating part as soon as you touch them together anyway.
Here’s why I wonder. Countless times I have aligned a tiny part to another using little jigs and clamping tweezers or small alligator clips and one of those muti position third hand gadgets and once set up I hit the joint with ultra thin plastic cement. I know the stuff essentially melts and fuses the plastic together like a weld. I wonder why doing the same with super glue liquid would not work the same way. I imagine they fuse parts together in different ways but considering that even if you apply superglue to one part only, the minute they touch it’s on both parts.
I assume it’s to reduce the amount that will squidge out of the joint? A double-thickness will only lead to a mess. Besides, putting it on only one surface halves the risk of me gluing myself to the parts!
The solvents used to fuse styrene parts together are way “thinner” than the thinnest CA.
The solvents get sucked in by capillary action (it flows into joints easier than water), soften the bonds between styrene molecules and then evaporates again.
Thin CA will also be sucked in by capillary action but the “pores” need to be larger.
You can test this with one of your fingerprints, gently press a fingertip against some hard surface, apply a small amount of CA to the point where skin meets surface and watch your finger getting glued to the surface.
Fingers across joints when gluing with solvents will result in 3D fingerprints on the styrene.
In same cases I have sanded down a resin part 1/32nd of an inch too much and then glued a styrene shim to the sanded surface. Then I can use a solvent to fuse the shim against the styrene kit. This allows me to position the part without any glue and then zap it in place with a solvent.
Glueing shims to two resin parts would make it possible to join them like two styrene parts.
If the contact points are that small there will be problem glueing them with CA as well.
The real issue is with the ratio of height vs width.
A contact point that is 1/32 of an inch in diameter is plenty big if the part is
only 1/16 of an inch high.
A 1/16th inch sized contact point is way too small if the part is 1/2 inch high.
@Rich just mentioned something that I had forgotten before.
CA is an adhesive, it grips both part of the joint mechanically and holds them together.
I have them and they should be secure enough for display, certainly not to handle which I never do anyway once done. Now what if you went around this joint when it dry by using a toothpick and some gel so when dried and touched up it would like like a weld?
If I were to do longer welds with CA I would try laying thin sewing thread where the weld is supposed to be placed and then carefully soak CA into the thread.
I would definitely try it on some scrap plastic first, before I ruin a built model …
Stretched sprue softened with solvent “glue” is another option. Shape with a tool when the stretched sprue is softened.
Search Armorama for various descriptions of how to simulate welds
