CA glue and Jo-Han promo plastic

[ChrisBcritter]

Had a little surprise when I was repairing the windshield header on the '67 Chrysler vert a while ago. The header had a break which I drilled out and pinned to make a strong fix, and I dabbed on a small amount of Zap-A-Gap CA glue. When I was dabbing I noticed the green color of the plastic was coming off on the toothpick I was applying the CA with, and indeed the plastic melted a little bit when I put the parts together, just like regular cement does with styrene. I always thought CA didn't do that; is there something in Zap-A-Gap that affects some types of plastic? Over to the experts...

[MrObsessive]

Chris, there is some kind of solvent in Zap-A-Gap. I remember this from when I was doing my '59 Chevy WIP and there was something I needed the Zap-A-Gap for. I noticed the the plastic became 'soft' so I waited till it dried for a couple hours and then sanded things away. You'd think this wouldn't happen but it does.

I'm at work so I can't see the bottle and what's in it, but I wouldn't be surprised if it has a small amount of MEK.

EDIT: I just remembered what I was doing then. Whenever I'm doing opening doors, I like to put a bead of CA around the inside and outside perimeter of the door jamb where I glued the plastic for strength. It was when I wanted to speed things up a bit that I noticed the plastic became a bit soft after I put on the accelerator.

So yeah..........if you want to do this, consider letting it dry just like you would regular glue, although it doesn't take as long.

Edited February 28, 2019 by MrObsessive

[peteski]

I don't ever recall any CA glue melting styrene, but liquid CA will readily start dissolving paint.

[MrObsessive]

27 minutes ago, peteski said:

I don't ever recall any CA glue melting styrene, but liquid CA will readily start dissolving paint.

I think he's talking about the accelerator you use to harden it up. I did have that soften the plastic......not the CA glue alone. And yes, CA can eat right into paint too.

[ChrisBcritter]

Thanks Bill! At least that will make the A-pillar joints a bit stronger. I'm being very careful working on this thing as I notice the plastic is brittle compared to some other promos. 

[peteski]

On 2/28/2019 at 4:38 AM, MrObsessive said:

I think he's talking about the accelerator you use to harden it up. I did have that soften the plastic......not the CA glue alone. And yes, CA can eat right into paint too.

Ah yes, some brands of accelerators can easily attack plastic. They use things liek acetone as their solvent. Zap-a-Gap I believe is one such accelerator. That is why my go-to CA accelerator is the BSI brand. Very mild and will not attack styrene (even clear styrene).  It might slightly mar fresh paint, but not like the acetone-based accelerators.

Edited March 2, 2019 by peteski

[ChrisBcritter]

Got the windshield frame fixed OK; had to glue one end at a time and tape it down very carefully so it held. While doing so I also slid a piece of a clear vinyl bag over the windshield to prevent fogging.

Just need to find some matching dark green stock to make the vent window posts - I'd cut a couple pieces from under the chassis like I did for another Jo-Han promo but this thing is too brittle to chance trying to get the chassis rivets out.

Now to try to cast a hood ornament!