I have used the wrong putty?

[Plastic Pilot]

Hello, I tried out to fill the gaps between the wings and the fuselage of the A-10, made by Italieri, and when I applied some pressure and they cracked both. I guess it is because of the elasticity of the plastic, but then I thought that it may be for using the wrong material to fill the gaps. Please can you tell me if it is the putty or the plane and how to solve this problem. But I bet it is the plane...

Thank you for your patience in advanced.​

 

[the Baron]

...and when I applied some pressure and they cracked both...

I think you hit the cause right there. I'm not sure there is any putty out there that will withstand pressure, in the end. Even 2-part epoxy putty. It's just a question of how much pressure you apply till the seam the putty fills pops open again.
I've never used that Vallejo putty, only Squadron's old formula White, Tamiya's putty, and Perfect Plastic Putty. They all did the job of filling a seam, but I never went back and put pressure on the joint, either.
Using sprue and liquid styrene cement might give you a slightly stronger join, but even a seam filled with styrene will probably break, eventually, under applied pressure. It's always going to be a weak point.
If that product works for you otherwise, I'd continue using it. Just don't apply pressure.

 

[smokeriderdon]

As mentioned, any putty is going to give way when pressure beyond the normal weight of the plane is applied to the seam. Not sure why you would be bending the wing down at this point.

 

[BlackSheepTwoOneFour]

Not sure why you would be bending the wing down at this point.

I couldn’t understand why he did that as well. You’re filling in the gaps, not changing the wings stance. Leave it alone once the gaps are filled in after sanding it down.

 

[Down Time]

I've been using Testors gray tube putty, works well for me, but as stated above, once a seam is filled and sanded leave it alone.
Just paint and admire your work, don't forget to share with us.

 

[trekriffic]

AVES Apoxy Sculpt might work. If you can get it.

 

[the Baron]

AVES Apoxy Sculpt might work. If you can get it.

I have to disagree. You can use a 2-part epoxy putty like Apoxie Sculpt to fill a seam, but it's still going to be a weak spot. Apply enough pressure to the filled-in seam, and it'll eventually pop. The putty'll be intact, but the join itself will open again.
If you're sculpting, though, Aves is an excellent product. I use it, myself, for sculpting.
Best regards,
Brad