Weekend Photos - July 2026

[webenda]

Fixed the boxcar with Hot Glue.

Interesting choice.

Ethylene-vinyl acetate (EVA), the common hot glue, uses terpene-phenol resin (TPR) as a bonding agent. TPR bonds well to ABS.
There is a trick to get the bond... both pieces of plastic have to get hot or the hot glue pulls off easily. Running a bead of hot glue and then putting the parts together does not work.

[Rufus T. Firefly]

......both pieces of plastic have to get hot....

Almost like welding it together. If it's ABS though you could use MEK, though I guess that could get messy...

[webenda]

......both pieces of plastic have to get hot....

Almost like welding it together.

I do not see it as "almost like welding." Welding is melting materials together. ABS plastic molecules are polarized. Hot Gluing plastic* is the electrostatic attraction of positive and negative charges between glue molecules and plastic molecules. Temperature plays a critical role in adhesion because higher temperatures allow the hot glue to flow into irregularities in the plastic surface, bringing more of the glue and plastic molecules closer together. The closer the hot glue and plastic molecules are, the greater the force pulling them together. As the adhesive cools, the polymer chains in both materials are “locked” in place, but the initial contact is governed by polarity and surface energy, not by a literal “turning” of molecules. The attraction between polarized molecules is known as van der Waals forces.

Note-- Van der Waals forces are considered weak, but with enough molecules attracting each other electrostatically, the total attraction can be enough for toy train cars.

*Hot gluing wood is different; it works because of mechanical interlocking—flowing into pores, grooves, or rough spots on the surface and hardening there.

Edit 1: Changed "share electrons" to "electrostatic attraction."

[Rufus T. Firefly]

......both pieces of plastic have to get hot....

Almost like welding it together.

I do not see it as "almost like welding." Welding is melting materials together. Hot Gluing plastic* is the sharing of electrons between glue atoms and plastic atoms. Temperature plays a critical role in adhesion because higher temperatures give electrons in materials more energy, making it more likely that electrons will be shared between the glue and the plastic. Sharing electrons is known as van der Waals forces.

Like I wrote "almost".... I'm not convinced that hot gluing involves sharing of electrons which would also be akin to covalent bonding.

[webenda]

Almost like welding it together.

I do not see it as "almost like welding." Welding is melting materials together. Hot Gluing plastic* is the sharing of electrons between glue atoms and plastic atoms. Temperature plays a critical role in adhesion because higher temperatures give electrons in materials more energy, making it more likely that electrons will be shared between the glue and the plastic. Sharing electrons is known as van der Waals forces.

Like I wrote "almost".... I'm not convinced that hot gluing involves sharing of electrons which would also be akin to covalent bonding.

You are correct. A covalent bond arises from the sharing of electrons between atoms. There are no shared electrons in hot gluing, just electrostatic forces.



Edit 1: Hot glue does not share electrons with what it bonds to. Changed the image and rewrote my original post.
Edit 2: Edited picture to show molecules and atoms.
Edit 3: Simplified text.
Edit 4: Whew!

[Rufus T. Firefly]

You are correct.

I am somewhat relieved.....

[webenda]

You are correct.

I am somewhat relieved.....

Me too; I just gained more understanding of glues. They are stingy, no sharing of electrons.

[healey36]

My favorite glue used to be LocTite GO2, but they stopped making that stuff. Now I'm using LocTite Extreme for most jobs...it seems to work pretty well and has a longer shelf life.

A number of my figure-painting associates have gone back to using PVA for most things, which kinda amazes me. One big advantage of that, however, is it's fairly easy to take stuff apart.

Now, when you guys start talking about mixing cyanoacrylate with other glues, that's where I start getting lost,

[Rufus T. Firefly]

Now, when you guys start talking about mixing cyanoacrylate with other glues, that's where I start getting lost,

[healey36]

Now, when you guys start talking about mixing cyanoacrylate with other glues, that's where I start getting lost,

There’s a place I pass driving up to York/Lancaster that’s an adhesive research center. I can’t remember the name of it, but I’ll bet there’s some crazy stuff going on in there.