Help and suggestions welcome glue problems - Aircraft of World War II

gijive · 01-31-2009, 02:47 PM

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 · 01-31-2009, 03:29 PM

Any pics?

Airframes · 01-31-2009, 05:36 PM

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 · 02-01-2009, 02:49 AM

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 · 02-01-2009, 12:37 PM

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.

01-31-2009, 02:47 PM	#1
gijive Senior Member Join Date: Jan 2009 Location: Yeovil, Somerset Posts: 168	Help and suggestions welcome glue problems 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? __________________ General warbird fan and model maker, mainly 1/72 scale. Facebook group: http://en-gb.facebook.com/group.php?gid=57402936784

01-31-2009, 03:29 PM	#2
Wurger Siggy Master Join Date: Jun 2005 Location: Poland Posts: 15,998	Any pics? __________________

02-01-2009, 02:49 AM	#4
gijive Senior Member Join Date: Jan 2009 Location: Yeovil, Somerset Posts: 168	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! __________________ General warbird fan and model maker, mainly 1/72 scale. Facebook group: http://en-gb.facebook.com/group.php?gid=57402936784 Last edited by gijive; 02-01-2009 at 03:56 AM.

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01-31-2009, 05:36 PM	#3
Airframes Senior Member Join Date: Aug 2008 Posts: 11,554	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.

02-01-2009, 12:37 PM	#5
Airframes Senior Member Join Date: Aug 2008 Posts: 11,554	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.