what am i doing wrong?

[flatheadgary]

i have seen several post about the type of glues used to build models, so i went and bought some. ambroid proweld, plastruct plastic weld and tenax-7r. my problem is, i can't get it to hold. i find it is hard to hold the model to wait for it to stick strong enough also. the same for super glue. even the capillary action won't work. it just doesn't hold. i scrape off the plating and such but it won't hold. what is the secret to this stuff?

i find the only thing that works for me is testors cement and 5 min epoxy.

thanks in advance.

[Jairus]

Gary,

I use all kinds of glue including what you mention. Each is best for whatever purpose depending on stress. Hinges are attached with epoxy because they get worked hard and have to live with undue stress.

However, there maybe something you are NOT taking into account and that is roughing up the gluing surface. I always rough up a surface with 80 or 100 grit sandpaper when strength is necessary. This gives the glue a 100% more surface area to grab onto.

Give it a try, especially with epoxy!

[MrObsessive]

Gary,

I ditto what Jairus said....................along with that make sure the plastic your working with is clean as a whistle! Oil on your hands or on your fingertips does not a good bond make. Especially in the hot, humid summer is this more acute.

I use Ambroid Pro Weld almost exclusively when doing body work (I just used it a few minutes ago on my '06 Magnum project) and have not run into any bonding problems as you've described.

[RyanSilva]

Ditto to what everyone has said, I like to back up the ambro weld with some super glue after the ambro has tacked up a bit. It holds it in place.

[hookedonplastics]

Gary, You are not working with resin are you? Just wondering.

[j_nigrelli]

i've never taken the trouble to roughen any mating surfaces but always make sure the parts fit as best as possible before glueing. with styrene cement, really a solvent, a little gentle pressure will help the softened parts make a nice tight fit. ACC (generic "superglue") is anerobic and cures in the absence of air, so again, a tight fit is a good joint.

also, and this is fairly important, don't use More than absolutely necessary. that's a sure way to have styrene solvent fail and ACC run down your arm. i will sometimes tack cement in a couple of spots to hold pieces in correct orientation and then come back and run a bead (after the tacks set up).

with ACC, i hold the parts up to my hobby light (100 watt bulb) for a bit to help get things going.

at least in my mind it works!

just keep at it - everything will fall into place. literally.

[Olle F]

Some superglue types seem to be a bit slow to cure, up to a minute for some. Actually, I don't know if it's the type of glue or a matter of how old it is, but I have a few bottles with CA that are much slower than others, and IMO that's easier to work with as it gives you a few seconds to adjust the part and make sure that it is in the right place and position. Then I spray some accelerator on it, and it bonds instantly. You shouldn't have any bonding problems if you use accelerator, CA glues seems to stick extremely well to anything around it... for better and for worse.

And I have never had any problems with liquid glue (like Tenax) either. I sand the surfaces to fit as nicely as possible, hold it in place with tape, rubber bands, my fingers or whatever is most convenient, then I brush it on the seam and let capillary action take care of the rest. However, it's important to know that most of the thin liquid glues are not really adhesives. They are solvents that dissolve the material and fuse it together. This is why they, unlike traditional adhesives, only work on on the material they are intended for. If the glue can't dissolve the material you're trying to glue (for example resin or plated parts), you'll never get it to bond.