Help and suggestions welcome glue problems

[gijive]

I'm building a P-36 Monogram model dated 1972 1/72 scale, nice little thing, however the glues not working very well, I have Revell pro glue and Humbrol liquid poly niether of which is holding well. The wing roots are the main problem, i'm now on a third rip them off and start again . I was sanding filler on them when the root cracked open. I even tired some super glue which is no better.

Any tips?

[Wurger]

Any pics?

[Airframes]

It might well be, if the kit is so old, that the plastic has 'matured'. Some of the Monogram kits from that era used a fairly hard plastic, and this might have changed over the years, becoming glazed, to the point where it is not reacting to cement. I'm not familar with that particular type of Revell adhesive. Is it actually polystyrene CEMENT, or glue for plastics?
If it is a glue, then the same result will be found with it, and with any 'Superglue' - it will bond, but will very easily separate. This is because the mated surfaces are only bonded by the glue, and not a chemical reaction.
With a poly CEMENT, it is not only the adhesive that bonds; the mated surfaces of the plastic are melted slightly by the reaction, and are fused together. You will have probably found that the liquid poly has done a better job, but has not got the strength. This is because, being thinner than 'tube' cement, it has not 'penetrated' the surface of the plastic as much, which is the the aim of liquid, as it's used for finer work, where the least amount of damage to the smaller components being joined will occur.
What I would suggest, is to first wash the parts, if possible, then abrade the joint surfaces, either by sanding, or by scoring with a scalpel or similar. You will need to remove any dried glue/cement first. This should cut through the hardened outer surface of the plastic which, in effect, has become resistant, rather like an armoured coating, due to aging. You may have noticed that the surfaces, before having adhesive applied, were fairly shiny.
If the Revell product mentioned is a cement, then it should begin to work. If it is not a cement, then you will need to obtain one. Normally, Humbrol and Revell 'regular' cements work exceptionally well, as do most other well-known brands, but some, such as 'Bison', are more glue than cement, and are best avoided when a clean, strong joint is required.
Note that any areas where 'Superglue' has been used, will need thorough removal of that glue. Superglue will not adhere to itself, and neither will other adhesives stick to hardend Superglue.
Another reason this could possibly be occuring, is too much cement being applied. As the adhesive cures,the reaction with the plastic is weakened, as the cement is bonding more to itself than the plastic. This is normally evidenced by what at first seems a good, dried joint, but one that will seaparate very easily as soon as any pressure is applied against it.
Before attempting any of the above suggstions, it would be a good idea to experiment with them on some of the sprue from the kit, treating it as if it was the kit parts. This should give an indication of which action to take.
Hope this helps, good luck,
Terry.

[gijive]

Thanks Terry, very comprehensive, it is poly cement, the one in the blue container that sits at an angle with yellow cap and a needle applicator. The plastic did melt a bit but not completely and this is also the case on the tail fins, they fall out as well. I am aware too much glue is a no no form my childhood days, I once made a Frog P-38 and the tail beam remained flexable for ever! I did try some super glue on the join as well, now I have taken it apart and cleaned it up. Will glue again later today after work. I think you are right old plastic.

This does not bode well for my future build of the Memphis Belle Revell kit also dated 1972!

[Airframes]

I think it should clean-up OK Chris - probably just hard, or maybe a lot of unseen reisdue of mould release-agent. I don't think you'll have a problem with the 'Belle; I used that kit to modifand super-detail about 18 years ago, as a re-issue, and it went together fine. The latest release will be new mouldings, so it should be OK. If in doubt, just lightly sand or score the mating surfaces if possible, but wash the parts first.

[Vengeance]

Hey gijive,
I've been using the Revel pro glue aswell and have had the same problem with getting a strong bond, With my current build (a Academy P-38m Lightning night fighter) I had a disaster last night when I was taping up wheel wells and the **** pit in preparation to spray. I'd filled and sanded and everything was going great. When I attempted to tape up the cockpit the rear seat came away from its mount and fell down into the body of the model "@#$%@&!!!!" I had to carefully take the model apart again to re-attach the seat and then re glue the entire model back together again. The wings and body needed cleaning up and the pieces fit together again fairly well. It's on the drying rack as I type and will need a complete going "back" over with the file and sand paper to clean it up again before paint. I have put it together using the Tamiya thin cement which should give me a better bond!!
Good luck with your projects!

[N4521U]

I gave up on Revell in the blue thingy just a while back when I had to buy Humbrol in the yellow container and have been happy as a clam. Even bonds styrene to everything. Good luck with your finding a solution.

[Airframes]

Strange, I've been using the Revell Professional 'Contacta', both in tube and nozzle version, for a couple of years without any problems.

[mikewint]

I use Tamiya's extra thin cement and for large pieces a "insta-cure" gap-filling cyanoacrylate glue. Pure Acetone can also be used but it will "melt" plastics if you use too much

[Rogi]

Wow I'm way behind the times, I use Testors in the red tube for plastic thats pretty thick and the blue tube for every other item (wings, cockpit etc) I've tried epoxys but Testors Blue non-toxic gives you enough time to move the bird around, I've been able to take it apart 4 days after glueing to adjust the parts, it gives it just enough hold to keep it together (unless you want to fly the model) and just enough of a looseness to it to be able to take it apart days after its "set".

I tried the Gunze glues but they were horrible, I had to add like ample amounts of it just to stick I couldn't add just a small amount and have them fit in. I also hated the smell( your not suposed to inhale but meh :S I don't have that kind of a work environement for models that allows ventilation, or else I'd be airbrushing the things indoors as well and saving myself months of waiting for spring to arrive)

[mikewint]

I airbrush indoors w/o ventilation all the time, but then I use acrylics. I put the model in a large cardboard box and spray away

[Rogi]

I use acrylics as well but I don't have the space indoors, unless I brush in the kitchen, but my mum would kill me for the mess lol

[mikewint]

How about your room? I used to use my computer desk. I put the box on the desk in front of the monitor and cleaned up in the bathroom. The focused spray of the airbrush produces little overspray

[Airframes]

I spray enamels, in the kitchen. Seems to give a different flavour to chicken pie I've noticed ....

[mikewint]

AH HA... Terry. NOW we know why the changes in your pics have taken place....