How to achieve a smooth finish with putty/filler

[Raven Morpheus]

Hey all

I've never been great at getting a smooth finish when filling gaps or eliminating seams with putty/filler.

I started out using Vallejo liquid putty (or whatever it's called, comes in a dropper bottle) but I found that to end up powdery and crumble when sanded, so instead I have been using Games Workshop's Liquid Green Stuff, and it worked great on my 1/48 Spitfire, however on my 1/35 UH-1C I did last year and more recently my WIP 1/48 UH-1N I found I can't get a smooth finish, despite sanding.

Can anyone recommend a better product to use? Or a technique to achieve a smooth finish?

TIA

Edited August 25, 2016 by Raven Morpheus

[Beard]

I use Humbrol filler rather than Green Stuff but I think the principle is the same: increasingly fine grades of emery paper and micromesh, used wet.

Some fillers, such as Perfect Plastic Putty and Milliput, can be smoothed with water or a damp piece of kitchen roll.

[Graham Boak]

Mr Dissolved Putty works well at filling excessive panel lines for me. You can always give a wash of Mr Surfacer before polishing.

Having said that for filling seams I tend just to reach for the nearest tube filler, which at the moment is the Humbrol. Milliput is better used for larger modifications - at least in my experience.

[tank152]

CA and Talc with a dash of pigment, mixed to your liking. Beats any modelling fillers hands down, no hanging around waiting for the stuff to dry, it doesn't shrink and can be scribed and polished to a very smooth finish.

[dubster72]

Although it's more effort because it comes in 2 parts, Miliput always gives me a nice smooth finish.

You can roll it out into tiny snakes to fit thin gaps & because it's water soluble, use a damp cotton bud to smooth it out. Hardly any sanding is needed.

HTH

[Dads203]

Tamiya basic putty is by far the best, it does shrink but not too much compared to the other brand,I did read that squadron putty still shrinks after 2 months of applying and drying and I always found it very grainy.

Miliput or any other 2 part epoxy does not shrink but takes time in curing, so not good if you are in a hurry. For small areas I like the Vallejo putty, you can clean it up with water and a cotton bud, those small areas do have to be small though, very good for wing joins

Epoxy putty is probably the best for sanding to a nice feathered edge if you use White miliput.

HTH

Dan

[John Laidlaw]

Dissolve chopped-up sprue/runner/tree/whatever you like to call it in glue - Tamiya Extra Thin, Tamiya not-at-all-thin, Methyl-Ethyl-Ketone, or Cellulose Thinners. When properly dissolved, it will flow into gaps, then cure to the same sort of finish as the plastic itself.

Then practice sanding/polishing. There is no substitute for practice.

[Raven Morpheus]

Thanks guys.

I've just seen Phil Flory on his DL-44 1 day build video on his youtube channel use the CA/Talc filler. Seems to be quite good, and probably quite cheap also.

I am after something that self levels and doesn't require a lot of sanding though, so not sure about CA/Talc, I've tried to sand neat CA before and it's like concrete, i.e. almost impossible to sand unless you get a dremel with a grinding attachment.

What I tend to get with LGS is it ends up looking like massive welds and even if I do get it smooth I still see a ridge at the edges. I'm very wary of putting a lot of effort into sanding due to the risk of removing surrounding plastic and obliterating details, or removing too much of the LGS, plus I don't want to be sitting sanding a small spot of filler for half an hour, for example.

Edited August 26, 2016 by Raven Morpheus

[Air Hockey Propellers]

I watched a youtube video where this guy mixed mr. white putty with thinner and used that instead. I didnt watch the whole video as Im uncomfortable with the smell of that putty and thinner.

However, having to use something as a filler, I decided to try the good old white glue. The one I have comes from a container with a very small end so I can dispense really small ammounts which I then even up with my good old fashioned finger. As you know , you cant sand or cut white glue once its dry so it either works from the start or you get it off wuth some good old water. Also, because the white glue shrinks somewhat, youll have to repeat the application a few times.

This might not be the most professional way of approaching this hobby but Im a relaxed modeller anyway.

[tank152]

I've just seen Phil Flory on his DL-44 1 day build video on his youtube channel use the CA/Talc filler. Seems to be quite good, and probably quite cheap also.

I am after something that self levels and doesn't require a lot of sanding though, so not sure about CA/Talc, I've tried to sand neat CA before and it's like concrete, i.e. almost impossible to sand unless you get a dremel with a grinding attachment.

This is why you mix Talc with your CA of choice, like you've found out, neat CA is a mare to sand, adding CA for some reason makes it sandable. A good trick when filling something is to lay a strip of masking tape either side of the joint, this will prevent filler getting where you don't want it and so cutting down on the sanding.

[Raven Morpheus]

Ah ok. I thought it'd just go rock hard like neat CA does.

I'll see if SWMBO has any talc in the house to give it a go, I have some filling to do on my current build.

[colin]

Don't leave the CA/Talc too long before you sand it, I tend to use a CA accelerator then get straight into the sanding.The longer you leave it the harder it is to sand.

But by far its the best for filling I find, no shrinking back, sands to a glass like finish and scribes lovely

[viscount806x]

I think that your problem may be more basic than type of putty in use. Smooth results can be obtained as suggested by other replies, by using water in the equation. Unfortunately, some putties do not take kindly to water, one of these being Vallejo which as discovered, crumbles to nowt. Fine Surface Polyfilla is as good as Vallejo and cheaper but suffers the same. The cotton bud in water treatment is the only way with these fellas or sand it dry but then you have a surface slightly contaminated with hand oils and dust which needs cleaning before painting, again, water is needed so not ideal.

I'm with the others who suggest switching to Green Stuff/Humbrol/Revell/Tamiya. That way you can work it wet and clean it afterwards with soapy water too.

[mirageiv]

+1 for CA mixed with things, perfect for normal size gaps or filling panel lines. If the gap is large, in that it will swallow a lot of CA, I usually fill it first with as much plasticard or stretched spruce first, then it usually only requires little touch ups of CA here and there.

The pure liquid melted spruce seems to give a lot of people success, imho I've found it can shrink and takes ages to dry properly. In that you think it is dry after a few days, sand it nice and smooth then find it has shrunken a little more a week down the line, which requires another application. Others have had much success with that so its just my own findings, I'd give it a go!

Just an example of the first CA method,

This kit had some ugly gaps which I knew would need rescribing. So first filled with plasticard shims and stretched spruce, let dry.

This was then sanded to a good surface but with a few little pinholes/smaller gaps still left, then a little CA+talk/baking soda over the top, sanded smooth and hard for scribing new lines if needed. A quick layer of primer to check, a few little issues left there but I would recommend those filling types for 99% of things from my experience.

For sink marks, I find Mr.surfacer of various grades is very good though to get the finest sanding from it I leave it a good 24hrs to fully cure, any earlier it doesn't seem to sand quite as nicely. Finally white milliput usually gets used somewhere on one of my builds, nice to use for nooks and gaps that would be hard to reach for sanding, certainly could not use CA for those bits.

I've tried Mr.dissolved putty but found it shrinks a lot on any sort of decent gap, requiring multiple applications which became a PITA, can be good for fine fuselage to wing gaps though when you remove the excess with Mr.color thinner.

A combo of CA+card/milliput/surfacer has sorted out anything I've ever needed to fill and I've built a few kits requiring a decent amount of it compared to modern tools.

Hope it is some use, cheers

David

[Air Hockey Propellers]

Wow, that's quite some detailed work there. Now I know what the experienced modelers have to go through to present those shrunken tanks. Maybe I joined the wrong forum...

My respect!