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General Aircraft: Tips & Techniques
Discussions on specific A/C building techniques.
Best filler for seam wing roots gaps, etc
propwash
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Charente, France
Joined: July 06, 2007
KitMaker: 289 posts
AeroScale: 231 posts
Posted: Monday, May 02, 2011 - 09:33 AM UTC
I currently use Tamiya Putty, but have found it cracks when sanding, especially in wing roots seams.

I'm looking for a general filler for medium gaps.....is Vallejo plastic putty any good? What fillers can others recommend?

TIA

P.S. one with as little or no odour would be favourite.
Keeperofsouls2099
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Florida, United States
Joined: January 14, 2009
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Posted: Monday, May 02, 2011 - 03:53 PM UTC
not really odorless but I use CA glue and some accelerator
ppawlak1
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Victoria, Australia
Joined: March 14, 2006
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Posted: Monday, May 02, 2011 - 07:07 PM UTC

Quoted Text

not really odorless but I use CA glue and some accelerator



Yes "Zap a Gap" CA and accelerator !!
warreni
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South Australia, Australia
Joined: August 14, 2007
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Posted: Monday, May 02, 2011 - 07:38 PM UTC
I use PVA glue. Never cracks, no need to sand if you apply it properly and it takes paint no problem. But I also use other methods depending on my mood.
MS406C
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Landes, France
Joined: May 22, 2008
KitMaker: 100 posts
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Posted: Monday, May 02, 2011 - 08:18 PM UTC
Yellow zap for the large gap at the wing root, Green one for smaller area, plus accelerator using an old airbrush needle to apply,it does not come any better!
propwash
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Charente, France
Joined: July 06, 2007
KitMaker: 289 posts
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Posted: Tuesday, May 03, 2011 - 12:31 AM UTC
Thanks for the replies, everyone!
mbittner
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Nebraska, United States
Joined: June 07, 2005
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Posted: Tuesday, May 03, 2011 - 03:02 AM UTC
Apoxie two-part putty. If you do it correctly, there will be little-to-no sanding involved.
chris1
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Auckland, New Zealand
Joined: October 25, 2005
KitMaker: 949 posts
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Posted: Tuesday, May 03, 2011 - 06:25 PM UTC
Hi Guys

Warren: I'm interested in some more info on your PVA method
How do you stop it from soaking up paint etc Isn't PVA water soluable?
Can you provide a SBS or more info please?

Cheers

An ANZAC cousin

Chris


drabslab
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European Union
Joined: September 28, 2004
KitMaker: 2,184 posts
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Posted: Wednesday, May 04, 2011 - 09:50 AM UTC

Quoted Text

I use PVA glue. Never cracks, no need to sand if you apply it properly and it takes paint no problem. But I also use other methods depending on my mood.





I never heard of this trick, it seems to good to be true

does it not develop cracs after a few years?

can you sand over it when needed?
Emeritus
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Uusimaa, Finland
Joined: March 30, 2004
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Posted: Wednesday, May 04, 2011 - 09:46 PM UTC
For smaller gaps PVA might be a good solution, but for larger ones, not so much. It shrinks when drying and remains slightly elastic when dry, so it can't really be sanded like putties or CA.

PVA is indeed water-soluble, but I wouldn't worry about it, as it's somewhat resistant to moisture when dry. It'll take a lot more moisture than a coat of acrylic paint to do any harm. There's also some more water-resistant PVA types available. It's also good to keep in mind that PVA doesn't adhere very well to smooth surfaces like plastics. This combined with the poor sandability, it's not suitable for smoothing surface scratches and the like.

I wouldn't recommend regular putties for seams that come under stress, like wing-fuselage gaps for example. I feel those are best first filled with styrene shims, then finished with putty, CA, or what-have-you.
Houston_Brit
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Texas, United States
Joined: May 08, 2011
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Posted: Tuesday, May 10, 2011 - 02:38 AM UTC
Hmm, define 'medium' gaps.

I almost always use Mr Surfacer 500 but its no good for gaps larger than about 1mm wide and often requires a couple of applications. On the plus side, i have never seen it crack and it is as sandable as plastic when dry.

Cheers,

Lee
chukw1
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California, United States
Joined: November 28, 2007
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Posted: Tuesday, May 10, 2011 - 03:36 AM UTC
I try to fill any significant gap with styrene- weld it in with liquid glue and it won't split or crack. Use any of the above-suggested fillers for the final smoothing and you're good to go!
propwash
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Charente, France
Joined: July 06, 2007
KitMaker: 289 posts
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Posted: Wednesday, May 11, 2011 - 04:34 AM UTC
Some great replies coming in...thanks guys
james84
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Roma, Italy
Joined: January 28, 2006
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Posted: Wednesday, May 11, 2011 - 07:40 PM UTC
If the gap is very wide, Gunze's white putty could be a great choice. No cracks, very easy to sand and less smelly than tamiya, but it's a pain to apply as it's very tough!
Spiderfrommars
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Milano, Italy
Joined: July 13, 2010
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Posted: Wednesday, May 11, 2011 - 09:47 PM UTC
Hi Alex

In my opinion Tamiya putty is very good , but anyway when the gap is large (more than 0,3 mm) I have several methods to fill it

First of all, if the gap position allows me to do it, I put in the the gap filled sprues or plastcard strips-thin roads. I wet it with tamiya thinner glue and I wait that they cured completely. After them I sand it and I apply a thin coat of Mr surfacer (500 or 1000 it depends on the surface smothness ). After them I sand it again and finally I polish with Tamiya polishing compound (Coarse grain). When the gap is large, applying only the putty could be not strong enough . In fact plastic and putty have different behaviours. Plastic is more elastic than putty. During the time or during the mounting phases putty could crack it. But if you put plastic in the gap you can avoid this problem.

Another method which I adopt consists in the use of Faller expert glue.



This glue melt strongly the plastic and tend to form a sort of plastic "sausage". This seems to be an issue but actually is an advantage because this seam weld replaces in a fantastic way the putty. So I aplly the glue on the contact surfaces (a LITTLE bigger amount than usual) and using rubber bands or clamps, I strongly bond the parts each other. If I do all in a right way the seam weld will go out. After then I Wait that the glue is perfectly cured (be careful...WELL CURED) and then I remove the seam weld with a very sharp blade. The gap usually disappears this way and you need just to sand it and polish a little bit. Sometime to fill few little dents, It could be necessary an aplication of Mr surfacer 1000

The third method which I use, consists in an application of White Milliput . I adopt this method when I have to prevent panel lines. The advantage is that you can smooth it with a cotton swab damp in water or alcohol

I don't use ca glue because i've noticed that is hard to sand it. Cured ca is harder than plastic so passing on it the sand paper you risk to damage the parts without smoothing it .Just my opinion anyway


cheers