What is THE best adhesive for plastic?

[Hawkmoon]

I have a set of black plastic (probably Springfield Armory) grips that were installed on a Sistema Modelo 27 to replace some ugly, Argentinean Pachmayr-like grips in an effort to make the Sistema look more original. The Springfield (?) black grips look correct for the pistol. But, one of them cracked through the upper screw hole and a corner broke off.

I would like to glue it back together and see if it'll hold. The way I look at it, more than likely I will only have one try, because once the mating surfaces have been contaminated with one type of adhesive, that will more than likely cause problems for any other types. So ...

If you had a broken plastic part that's thin and subject to occasional handling, and you only have one chance to put it together and have it hold -- what's the best adhesive for the job? Epoxy? Crazy Glue? ???

[Tom]

I've had good luck with Crazy Glue and its clones, as long as the piece doesn't bear any stress. I've used it to repair the "feet" underneath computer keyboards even, as long as one didn't flip the part in and out frequently. So I would think that Crazy Glue should work.

If you really want to be sure, once the piece is glued into place, you could then whip up an amount of epoxy and spread that along the inside of the grip to give it extra stability.

[niemi24s]

Not knowing what type of plastic the grip's made of here's what I'd do: With a small, sharp gouge peel a little strip of plastic off the inside of the grip panel and (after cleaning the little strip and a spot on the inside of the grip real well with alcohol) see if the Crazy Glue will work.

There are some plastics I've never been able to mend with Crazy Glue, but I've never tried them after treating those surfaces with a sensitizer.

If the grip material is such that a little test strip can't be obtained and the broken piece is completely separated, a good (long curing time) epoxy may be your best one-shot chance.

Rotsa ruck! :p

Cheers

[RobL]

The type of plastic is everything. Some times will not stick to CA glues (Krazy Glue) at all (it will peel off), some will sorta-kinda stick but be fragile, others will stick very well. Epoxy is a better choice for a 1-shot deal because it has a better chance. Even then, it's not 100%; you will find plastics from which ordinary epoxies can be simply peeled off.

Niemi's method works if your plastic isn't too hard. If it is, then maybe consider finding or making a recessed portion of the plastic and putting a drop of glue in there to see if it will stick (rather than trying to get a strip of material off).

Another thought: consider laminating some kind of very thin reinforcement on the back of the grips. Even a few pieces of thread or a really thin piece of cloth saturated with glue will reduce your odds of future breakage considerably.

[TJH3781]

How about laminating plastic to reinforce the area. It is thin & would cover the whole grip panel. It may work as a hinge & then you could glue the parts together. I would try a thin coat of epoxy as the glue.

[Liftrat]

I agree that the type of plastic makes all the difference. I've used Devcon's plastic epoxy with good results on plexiglass panels, but it only works OK on my chrono skyscreen legs. I have a vial of Loctite's plastic superglue, but haven't had the opportunity to try it yet. Another thought might be plastic model cement. I know in the last many years they've wimped it down to discourage sniffing, but it is made for plastics. Good luck.

[Dexter]

Niemi's on the right track; the only way to know for sure is to try it on that particular material, so that's what I have usually done, whenever I've accidently knocked one of the wife's trinkets down... test it on a hidden area first. More often than not, Crazy Glue works fine. The really nice feature of a product like that is that it has minimal thickness, unlike some of the more "professional" products. The tricks are to not "prep" the fitted surfaces, other than wipe them off, because you want all of the little bumps, nicks, etc. to match up, and then make sure you figure out how you are going to clamp it before fitting it, so that you can apply the glue, mate the two pieces, set it down, and walk away from it.

[niemi24s]

Hi Hawkmoon:

Don't know what this might mean for the grips you're trying to fix, but the Ordnance spec calls for them to be made of a phenolic plastic.

When the adhesive decision is made, here's a tip for aligning the pieces prior to joining them: fix the big piece to something nice & flat with a layer of waxed paper underneath and extending beyond the joint to be made. This way, you'll have automatically aligned the two pieces in the Z-Axis and the waxed paper will keep you from glueing the grip to whatever you do the work on.

[Old trick picked up from years mis-spent building stick & paper model airplanes! :p ]

Cheers

[log man]

This stuff, Super T really works on everything I've tried it on, rubber ,plastics wood, metal. With the accelerator you will be amazed, I have both glues and the accelerator, and the solvent and will never be without it in my box. While you're at it get the super solvent also gets it off stuff and your fingers.

http://www.brownells.com/aspx/ns/store/ProductDetail.aspx?p=13081&title=HOT%20STUFF%20INSTANT%20GLUE

http://www.brownells.com/aspx/ns/store/ProductDetail.aspx?p=25678&title=NCF%20QUICK%20AEROSOL%20ACCELERATORS

http://www.brownells.com/aspx/ns/store/ProductDetail.aspx?p=25679&title=SUPER%20SOLVENT

LOG

[PhantomAce]

Never attempted on grips, but I have repaired other things in the following manner, and results have generally been good...
Very, VERY fine line of epoxy at the repair joint.
Once applied, clamp and set with masking tape. Put a piece of wax paper that has been lightly oiled with vegetable oil under the masking tape. (Don't leave the wax paper "naked", some epoxies will even try to bond to it. The result is wax in the joint, nice and shiny. A slight lube film though can be removed, even from the surface of the epoxy, with a bit of isopropyl alcohol in most cases.)
Once set, bond a piece of thin cloth to the backside (think fine cloth, like old worn silk pillow-case fine), and let it cure again. You can always color the cloth after, if you feel the need.
The epoxy bonds, the wax paper prevents the clamp (tape) from sticking to the joint, the tape compresses for a good bond, and the cloth provides "structure" with flexibility.
May not be the best fix (new grips would be, technically), but a grip doesn't really have that much torsional or sheer load once it's installed anyway, right?
As long as the bond can survive high freq vibration/shockwave and temperature variation, it should stay intact. And, the worst you did, assuming it works as anticipated, is increase the thickness whatever the cloth was.
I'm currently rebuilding a 48 year old car, ground up, that not a lot of parts are available for. You'd be amazed what you can come up with if you need to. Necessity being the "Mother of Invention" and all that...

[Pappy]

When I was in the plastics industry there was/is one plastic that could not be glued....polyethylene i.e. gallon milk jugs.

Parts had to be joined by mechanical means or melting.

But I doubt your grips are polyethylene...

[niemi24s]

When I was in the plastics industry there was/is one plastic that could not be glued....polyethylene i.e. gallon milk jugs.Loctite's got some stuff that they advertise as being able to bond that stuff - and polypropylene too: http://www.loctiteproducts.com/products/detail.asp?catid=17&subid=40&plid=661 Haven't tried it, but it almost sounds too good to be true.

Maybe it is.

Cheers

[Pappy]

Loctite's got some stuff that they advertise as being able to bond that stuff - and polypropylene too: Haven't tried it, but it almost sounds too good to be true.

Maybe it is.

Cheers

I've been retired from plastics for 10 years now...perhaps Loctite does have something that works..

"Simply apply the Activator using the felt-tip applicator, wait 1 minute, and apply the Glue"!

Wonder what the 'Activator' really does??? PE and PP were/are used to contain acids and bases.. :confused:

[niemi24s]

Wonder what the 'Activator' really does???Don't really know, but I'm guessing it might be something like tetrahydrofuran which (as I dimly recall from some organic chemistry course) is one of the ingredients in PVC cement and can even dissolve nylon.