Why is my CA glue not bonding?

[DWPC]

I attempted to "stitch" two hull halves together every 2" or so with Duro Super Glue, then go back over the whole seam with an Testors old school tube. Technique was to apply a drop between the surfaces, then squeeze them firmly together for a minute or so. The CA would not hold (though it worked great on fingers!). The tube is about two years old, and freshly opened. I ended up relying only on masking tape to hold the half hulls together and glued it with the Testors, and Tamiya Thin, which came out OK. I'm new to using CA on styrene an wondered if my technique is wrong. Any ideas why the CA didn't bond?

[Timmy C]

Did the CA itself dry at all, or remained liquid? CA requires moisture to cure, so if your region is very dry, the amount of air inbetween the two hull halves may not be sufficient to cure the CA.

Incidentally, CA isn't imperative for gluing two styrene parts together - the styrene cement should suffice. Use the Testors tube glue first, then put the hull halves together, then brush the Tamiya thin along the seam from the outside. Thin cement like Tamiya is meant for application along the seam, allowing capillary action to flow it along.

[DWPC]

Did the CA itself dry at all, or remained liquid? CA remains moisture to cure, so if your region is very dry, the amount of air inbetween the two hull halves may not be sufficient to cure the CA.

Incidentally, CA isn't imperative for gluing two styrene parts together - the styrene cement should suffice. Use the Testors tube glue first, then put the hull halves together, then brush the Tamiya thin along the seam from the outside. Thin cement like Tamiya is meant for application along the seam, allowing capillary action to flow it along.

It is somewhat dry here, but we keep a humidifier set at 35% in the same room where my work table sits. I did try breathing on it, but to no avail. It dried eventually, all was dry this morning.

[gott_cha]

From (my) experience I have found CA to be great for quick bonding of dissimilar materials and for gap filling. But not so good or long lasting for major assemblies. I have a couple of my early builds where CA was used exclusively and over time (3 to5) years, seams have opened and cracks have appeared.
Being that CA is a bonding agent and not a solvent,..it's subject to weather related expansion and retraction. live and learn for me.
Normal Hobby glues are of course "Solvents" that actually dissolve and weld the plastic creating a more permanent bond. For high stress areas like ship hulls and maybe Aircraft fuselages CA just doesn't make the grade.....for me anyway.
I have had the best luck with the TESTORS red tube...and Liquid solvents.

And yes the weather can and will affect the curing of CA

[DWPC]

I have had the best luck with the TESTORS red tube...and Liquid solvents.

And yes the weather can and will affect the curing of CA

I'm using Testors red tube, Tamiya Thin, and Testors Liquid. I was using the CA as an assembly aid and wouldn't rely on it for permanent bonding.

[sgtryan13]

If you were using a trumpeter kit with the red lower hull, that red plastic is a different type of plastic than the rest of the kit, and is all around horrible for modeling purposes. CA glue adheres horribly to that red plastic, as does paint if a good primer is not used.

[biggles2]

Any super glue (CA) will bond only when the two parts are really firmly pressed together. Even if there's only a hair's breadth between the two parts, the CA will not bond. CA is not the ideal glue for plastic, anyway. A sharp knock in the right (or wrong!) place could cause the joint to split - not good after the model is built! I always use a thick-ish plastic glue (so it doesn't evaporate too quickly) on both hull halves and firmly press them together, and hold for a few minutes. The two halves should weld together for a strong bond.
As for air being needed to cure CA, I believe the opposite is true. You can squeeze out a few drops of CA for use, and it will stay liquidy and useable for a few hours. Drop a part into the CA puddle, and it will immediately bond to the bottom of the container!

[Eric Bergerud]

I wouldn't recommend CA on plastic to plastic bonds. What happens is the CA bonds to the plastic, but the plastic isn't effected at all - almost like a permanent rubber band. If you have two parts each with CA on them, the CA bonds to the CA. That's why it works so well with PE or materials that plastic cement won't bond to. That said, CA definitely loses it's bonding ability over time. You might want to get a new bottle. Zap and Gap is certainly the best and the green label (medium) is very versatile. I take it you're using "kicker" which bonds the stuff instantly. So does baking powder. Both leave a coarse seam but CA sands well.

Tamiya thin (or similar very thin and strong bonding glues) dries very quickly so sometimes it's not ideal on it's own. But such cements do melt plastic better than tube stuff - which I wouldn't use. (If nothing else, it doesn't have an applicator brush.) Try this: Tamiya sells both Thin (green cap) and Thick (orange cap): get both of them. I throw money at problems so I'd get two of each and find an empty bottle and mix the thin/thick stuff together 1:1. So you've got three types of glue that dry differently and the orange stuff or the mix will give you a very solid bond when it dries.

Eric

[DWPC]

Since I first posted this, I've tried out several cements and will likely stay with Testors Liquid (with the needle applicator) and Tamiya Extra Thin. On non-delicate parts, I like the red Testors tube glue. I've still had no success getting an instant CA bond to styrene to hold parts while applying solvent cement. Still works fine on fingers, though.

[Eric Bergerud]

Testors is a lot like Tamiya orange. If you have a empty glue bottle with a brush cap, try mixing a little Tamiya thin and Testors liquid together - that leaves you essentially with three glues. I use the mix a lot.
Eric

[el Cid]

Like others said, not preferred for styrene-to-styrene, but...

How old is your CA? In my experience of on-again, off-again modeling, I think CA goes bad over time, especially after it's been opened. When I start a new project (or more often re-start an old one) I pick up a fresh bottle of CA and avoid the frustration of slow-, or non-curing CA.

HTH,

Keith

[biggles2]

CA is said to keep better in the fridge.

[DWPC]

Like others said, not preferred for styrene-to-styrene, but...

How old is your CA? In my experience of on-again, off-again modeling, I think CA goes bad over time, especially after it's been opened. When I start a new project (or more often re-start an old one) I pick up a fresh bottle of CA and avoid the frustration of slow-, or non-curing CA.

HTH,

Keith

Initial problem was with CA that was a couple years old but unopened. I also bought some thick CA that, too, was not instant bond on plastic but was instant when used on metal.

[Mgunns]

I have used Methyl Ethyl Ketone for cement for over 30 years with no ill affect. It is the basic bonding material in Testors and other liquid cements. You can get it at any hardware store and a pint can will last years at a fraction of the cost of Testors. I pour it into old Testors bottles with a funnel. It also works great as a paint thinner for enamels and Tamiya Acrylics only. Any other acrylic it is used in gums up. It's also a great brush thinner.

[Eric Bergerud]

Have you ever used "Kicker" - that's a fluid sold in a spray bottle at model shops for instantly setting CA. Baking soda will also work, if you've got a hand free. Both do the job as advertised - they will freeze parts almost instantly. But as noted above, CA is not the ideal medium for styrene on styrene.

I'm not sure what size of parts we're talking about, but if you're looking for something that will hold a piece in place so you can put on another kind of glue, find some Aleene's "Tacky" Glue: it comes in many varieties but all will grab a part almost like a magnet if it's small enough. Aleene's is a type of white glue so it's not ideal for gluing major pieces by itself. (Very good brew for use on PE railings - might want to add a couple of little dots of CA.) Just leave some spare space on the parts so the plastic cement can touch both sides of a join and melt the seam.
Eric