Good plastic cement gone bad?

[Landshark]

I had a strange thing happen when I used Testor's plastic cement (orange tube) on some rocket parts lately.

I bought the tube from Hobby Lobby or some place like it and used it on the nosecone of my son's "Cosmic Cobra" (the part where the helicopter hub bonds to the nosecone shoulder) and also on the fins/launch lugs of my new Estes D-Region Tomahawk.

The surfaces were clean and that cement is what the instructions recommend, but when we got out to the launch site a few weeks later, the cement bonds completely failed. I went to put the Tomahawk on the launch rod and the lugs popped off like they'd been stuck on with icing or something. Managed to fix those with CA and then sent the rocket up. Great flight, but it dislodged two of the four fins in high, soft grass upon recovery.

I didn't think this was overly odd because of the other posts I read about reinforcing the fin bonds on that one with more of a "solvent" type plastic weld solution, but then we got ready to launch the Cosmic Cobra and had another incident.

My son pulled off the nose cone to pack the chute and the copter hub literally fell off in his hands! WTH? CA came to the rescue again, but has anyone else seen this with this type of cement? I've used this type / brand of cement for years with no problems... Am I missing something? Could it have just been old cement or something?

 

[dpower]

I'm sure someone will pipe in here with more chemically accurate details, but in my experience, testors tube type cement simply does not work on estes plastic parts. It is intended for styrene (think plastic models), and estes kits use some other type of plastic. I have no idea why they continue to recommend it. I've had reasonably good success with liquid cement, such as Ambroid pro-weld, though sometimes use epoxy (after roughening up the surfaces).

 

[gpoehlein]

dpower is right - Testors tube cement doesn't work on Estes plastic parts any more (they used to be styrene but aren't any more). I use a liquid cement called Tenax that I get from my local hobby shop. It is intended to be wicked into the joint while you hold the joint together. I have also brushed a couple of coats on the joint to be glued (nose cone shoulders) and the second coat usually stays soft just long enough to get the parts together. Tenax is designed to cement just about any type of plastic so it is highly recommended.

 

[JoeG]

Agreed that Tenax is about the best. They have just stopped distributing it through major suppliers though and may be difficult to find.

Most of the plastic weld types are pretty good. I am now stocking the Plastistruct "Plasti Weld" and it works very well. Takes just a little longer to set up than Tenax. Sometimes that can be a good thing.

 

[MarkII]

Tenax-7R does work really well, but the parts must mate together perfectly, because it won't fill even very minor gaps. It does soften the surface of the plastic, but only very superficially. If the parts are well-mated, that is usually more than enough, though. Testor's does make brush-on model cement in a bottle, not a tube, but I don't know if it would work better. I have heard goo things about the Plastistruct product, too. I have a bottle of it (bought last year!) but I haven't had an occasion to try it yet.

Although I haven't tried it for this, BSI Maxi-Cure CA is supposed to work well for plastic, too.

MarkII

 

[powderburner]

I agree with all these other guys, model cement in tubes is just not what it used to be. I am not sure I recommend it even for styrene kits (my son just started building a Panzer and I bought him a bottle-n-brush glue with MEK solvent in it).

Tube cements have been steadily re-formulated (that is, weakened) over past decades to take out the chemicals that made it so popular to sniff glue. Unfortunately, these are the same chemicals that made the glue work. I don't think tube glues are worth c##p anymore.

FWIW, if you absolutely MUST use tube glue, try scuff-sanding the joining surfaces first with an emery board or a needle file.

 

[luke strawwalker]

I agree with all these other guys, model cement in tubes is just not what it used to be. I am not sure I recommend it even for styrene kits (my son just started building a Panzer and I bought him a bottle-n-brush glue with MEK solvent in it).

Tube cements have been steadily re-formulated (that is, weakened) over past decades to take out the chemicals that made it so popular to sniff glue. Unfortunately, these are the same chemicals that made the glue work. I don't think tube glues are worth c##p anymore.

FWIW, if you absolutely MUST use tube glue, try scuff-sanding the joining surfaces first with an emery board or a needle file.

Yeah, you're right about that... they've 'detuned' the product to the point that it's worthless...

I was reading that Testor's has some kind of glue out that is basically concentrated citric acid and that it's TOTALLY worthless--- basically you're trying to assemble your model with ORANGE JUICE...

Might be okay for a plastic model that will only sit on a shelf, but NOT for ANY kind of model that will be handled-- let alone FLY... OL JR

 

[spacecadet]

Methylene chloride is the stuff. You have to be careful with it, and you can only get it if your other half works in a chemistry lab, but it's the only thing for ABS, which is probably what the Estes parts are now (looks and feels like polystyrene, but just crazes with polystyrene cement).

 

[gpoehlein]

Yeah, you're right about that... they've 'detuned' the product to the point that it's worthless...

I was reading that Testor's has some kind of glue out that is basically concentrated citric acid and that it's TOTALLY worthless--- basically you're trying to assemble your model with ORANGE JUICE...

Might be okay for a plastic model that will only sit on a shelf, but NOT for ANY kind of model that will be handled-- let alone FLY... OL JR

The orange based stuff has been out for a long time (>20 years I think) - it comes in a blue tube. It was created both to make the glue "safe" for the kiddies as well as to combat glue sniffing. You are right - it is really worthless to build even styrene models - and yet it still sells.

As a side story, I remember one year when I worked part time at our local hobby shop. About every week or so, this really scruffy looking guy with long stringy hair would come in and buy about a dozen tubes of regular Testors cement. He always asked if we would be sure to put it in a paper bag.

 

[MarkII]

As a side story, I remember one year when I worked part time at our local hobby shop. About every week or so, this really scruffy looking guy with long stringy hair would come in and buy about a dozen tubes of regular Testors cement. He always asked if we would be sure to put it in a paper bag.

So that he wouldn't have to expend the mental effort to scrounge one up for himself. I know that it has been a problem in the past, but in the course of my professional work or in my personal experience I have never come across anyone who actually did any huffing.

MarkII

 

[tbzep]

So that he wouldn't have to expend the mental effort to scrounge one up for himself. I know that it has been a problem in the past, but in the course of my professional work or in my personal experience I have never come across anyone who actually did any huffing.

MarkII

You mean you haven't met the Warrior fan?