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Filling and sanding techniques

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Hi all,

I’m sure for many this is a simple question, but I guess we’ve all gotta ask occasionally. Currently having issues with my Revell 1/48 Typhoon, in that when I’m sanding down the filler, all sorts of gaps/little craters are appearing, an issue which I’m increasingly confident is down to me as I’ve tried at least 3/4 times to achieve something I’m happy with by refilling/resanding . So essentially I’m after some fundamental filling/sanding tips to see if I’m doing something very wrong. 
Thank you 

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10 minutes ago, bmwh548 said:

What type of filler? How thick are you applying it? How long are you letting it dry? Which areas are you filling?

I’m currently having my difficulty with the wing/fuselage joins as well as the airbake. I’m using squadron products white putty, with generous applications allowed to dry for 2+ hours 

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1 hour ago, Harry Fraser-Urquhart said:

So essentially I’m after some fundamental filling/sanding tips to see if I’m doing something very wrong. 

Squadron putty, and mots one part putties shink when they dry.


As for gap filling.  I have some unfinished or disassembled  kits from my early teens that are putty monsters.  No I look at them and think, crickey , that was dumb, what a mess.  Then I'd assmble, and then try to fix the problems with filler. 


First, minimise filling and sanding if you can , 


Some suggestions.   


Avoid gaps in the first place, by this I mean sometimes they can be eliminated by scraping and sanding of joints, or assemble differently, say a place with one piece lower wing, and two upper wings (eg a Spitfire) you can attach the upper wings to the fuselage, and then when dry, the lower wings, eliminating wing root seams. 


It's worth dry assembling main bits, and also check that bulkheads and interior parts are not causing gaps,  many new tool kits have incredibly tight tolerances, and a coat of paint or missed sprue nib, or even a slight misalignment in an early part of assembly can cause major problems later ( example are old tool 1/48 Eduard fw190A and the new tool 1/48th Airfix Spitfire Vb/I) 


Worth seeing how canopies fit as well at this stage. 


For an even width gap, long or short,   use a strip of plastic, and then trim back.   You may eve be able to get the strip to a point where it will need minimal trimming. 


Or use a shim before assembly, when it might be easier to add.  I use superglue for this, as you can frequently be trimming back in a minute.  Being the same material it sands and rescribes and takes paint the same.


Check that alignment pins are not an issue, sometimes they are, enlarging the hole part can help, or sometimes remove altogether.  You may need to add your own alignment parts, which can avoid gaps and mis alignments, or perhaps a spreader bar.    

Things like tank hulls can benefit from this, and makes sure they are all square and true.


This may sound a faff, but it's a lot less faff than messing about with multiple filler applications later on.


use superglue and superglue/talc as filler, dries fast, does not shrink.  if just using neat SG, work as soon as hard, as when fully cured it's harder than the plastic.   SG talc can be mixed in varying proportion as well.  


I personally don't like the one part fillers.  Milliput, when annoying mixing up, does not shrink, and can be water smoothed to minimise sanding.


Note meant as a lecture, the above are all techniques I have used and found helpful.




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Hi Harry


I could never get on with Squadron putty as it seemed to tear away from the model when sanding but probably my fault. I use Milliput for major gaps and depressions ( easily moulded into shape with wet knife blade) and Perfect Plastic Putty for minor gaps where excess can be removed with the swipe of a damp cotton bud.



Edited by mick b
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Fully concur with Troy's comments re: super glue and talc. Once any chasms are mitigated with plastic strip etc SG/talc will not only fill without shrinking but will add strength too, and can be sanded or scraped in minutes, or even quicker if you use an accelerator. I know better modellers than myself who swear by Milliput though, and the ability to smooth with a damp finger or cotton bud is very persuasive, although it dries slower. Mind you, that can be an advantage. Mike is absolutely correct. Swings and roundabouts. 

Edited by modelmaker
Forgot something!
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I've just filled the poorly defined & spurious panel lines in some Airfix Beaufighter rockets using superglue & talc and have followed up with a lick of Mr Surfacer 500 (which is currently drying).

The superglue/talc mix took around 5 mins to dry and sanded really easily with sanding sticks. It filled most of what I wanted it to, the Mr Surfacer is to check my sanding and fill tiny imperfections.


In my pretty limited experience I have found that the less filler used the better.




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I only use CA to build kits and I also use it to fill gaps, if the gap is big then I will fill it with scrap plastic and top up with CA, however I never leave the CA to harden too much as it will take forever to sand away. I either use accelerator or leave it for half and hour or so before sanding. The other filler I use is Mr Surfacer, but only for fine gaps where there is meant to be a panel line, I apply the Mr Surfacer with a cocktail stick and wipe away the excess with a cotton bud dipped lightly in Mr Color thinner, this fills the gap but leaves a line.

Just filled this with CA







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