Filler recommendations

[barhamd]

I watch Youtube videos with aero modellers building plastic kits and they seem to be able to apply filler to hid joints. It looks so easy with a bead of filler being applied, adhering to the plastic, drying solid and filing smoothly.

Whenever I try to use filler, seemingly regardless of which filler I use, it never seems to adhere properly to the surface, never seems to go completely solid, when I try to sand it it just seems to peel away.
I've tried Humbrol filler, Mr White Putty, Vallejo Plastic putty.

What am I doing wrong?
David

[Stephan.wintner]

All I can think of is that the joint surface is not clean - either a mold release is still present, or something is contaminating it.

I've used Tamiya and Mr White, as well as some others. Mr. Hobby sells some liquid fillers too, for example.

What adhesive or solvent did you use to secure the joint? How long did you let it cure before filling?

I'd suggest using an adhesive and filler from the same brand, if you've not tried that, and letting the adhesive cure for at least 24 hours before filling.

Stephan

[barhamd]

Typically it has been white metal stuck to brass using superglue.

David

[Tim V]

My favourite is Miliput. Note that this has a shelf life - about two years.

Also in my armoury is Squadron Putty - shelf life not known!

[Stephan.wintner]

Ah. Well most fillers I've seen are intended for use on styrene. I'd still expect them to harden, but adhesion to metal could be an issue, that would not surprise me. Using an etching primer first might help. Miliput is a 2 part epoxy (or anyway the one i have is) and would likely adhere well.

Cyanoacrylate can also be used as a filler, and works nicely if you can get the right balance between gap size and viscosity. Using a CA debonder can remove excess if it spreads too far.

Regardless, cleaning the surfaces well and letting the CA cure thoroughly (24 hours) should help?

Stephan

[Guy Rixon]

David Dumek, a skilled maker of plastic models who publishes on YouTube, recommends a flexible form of cyanoacrylate glue as a filler. He uses this on polystyrene kits for the more stressed seams, such as gaps between halves of aircraft models. Apparently the glue sands very well when set. It's a specific kind of CA glue, but I don't know the brand.

[David B]

I have taken to using Apoxie, a 2 part epoxy which I press in then finish with a brush dipped in water. I have been very pleased with the results and it sands well although I try to leave it as I want it with the brush.

It's not cheap though. The price has risen quite a lot since I bought mine but it seems to keep very well in the tubs and is easy to use. I even mended a suitcase handle with it. I think Milliput is similar but I have not found it as easy to deal with and my purchases in the past went very hard.

See: Apoxie Sculpt

[Will L]

Typically it has been white metal stuck to brass using superglue.

Possibly a bit late now but - Why didn't you use low melt to solder the white metal to the brass. Low melt make quite a good filler. Do it right and then the issue becomes cleaning off excess solder. It will be solid, it wont peal off and you don't have to wait for it to set.

[John Donnelly]

I use either Deluxe materials Perfect Plastic Putty which is water soluble so the vast majority of excess can be wiped away with a damp cotton but leaving, in a lot of cases, no other clean up to be done or I use a mix of super glue and metallic (it has to be metallic) pigment which fills and sands well.

John

[David B]

John's post reminds me of something I learned a couple of years ago. Fill a gap/hole/blemish with fine powder like bicarbonate or (and I laid hands on some) dental resin. Add a drop of liquid cyano - runnier the better. Leave to harden. I have managed to replace some thin flat resin, thin as in 0.3mm, like this.

Here is an interesting You Tube video: Dental Acrylic for Scale Model Construction. Other Scale Model Workshop videos are also interesting and informative, especially those on tools and techniques. There is even on on using Apoxie.

One more: Baking Soda and Super Glue

[Tony Wilkins]

I have used talcum powder and cyano glue in the past. I would also suggest using one of the proprietary brands of car body filler as this is intended for metals although there are now also variants intended for repairing plastic bumpers.
Regards
Tony.

[barhamd]

Thanks for the responses so far.
I avoided using low melt as a filler because me+white metal+solder=blob and I also have issues with 3D printed parts.
I've heard people mention baking powder and superglue, is there some reason why baking powder is a good material? I guess this goes solid almost instantaneously?

David

[David B]

I avoided using low melt as a filler because me+white metal+solder=blob . . .

What temperature do you have your iron on? How big is the bit? Shouldn't be a problem. Practise on some scrap white metal. Practise . . .

. . . is there some reason why baking powder is a good material?

I suspect it is because the bicarbonate has very small, fine grains.

[Stephan.wintner]

A brief chat with my chemical engineer father makes me think various powders with CA will behave differently.

Baking soda or bicarbonate should react very quickly. Talc, dental resin, and baking powder likely set up slower because they have a less fine grain structure and do not absorb the oxygen which is dissolved into the fluid CA.

In my limited experience, sprinkling baking soda onto CA did not give good results and I suspect powder then CA would be the way to go.

Stephan

[kelly]

A couple of options I've seen used by wargaming modellers have been:

1, green stuff. An epoxy putty, mixed like miliput, but works a bit different than miliput and is perhaps better for finer detail. Miliput to fill big gaps, then green stuff to add the detail on top is one method used.

2, small beads of plastic (from sprues) mixed into something like tamiya thin (or similar glues). It creates a liquid paste that fills quite well and when it dries you can work it like plastic as it is pretty much plastic after it has dried.

The superglue + baking powder is also used by them quite a bit too.

I've used tamiya putty a fair amount, and whilst it stinks like hell, it works well. Like miliput it has a shelf life once opened of around a year or so, maybe less depending upon certain factors (humidity, heat etc). The humbrol stuff is fairly similar in many ways.

[Martin Wynne]

The superglue + baking powder is also used by them quite a bit too

Martin.

[Neil Smith]

That looks great, but what's the gas/smoke that comes off (especially in the plug reconstruction bit of Martin's video)? Given the propensity for CA glue to break down to cyanide, I'd rather know before trying this...?!

[Hardwicke]

Reading online it seems to be water vapour and carbon dioxide

[David B]

I have used the powder and liquid cyano and it is very effective, once filling in a broken resin mudguard (0.4mm thick) on a car. It dries rock hard and is easily sanded. Older cyano does not work as well - use fresh - nor does it work with the gel type.

Because I was not using a teaspoon of the stuff and just a couple of drops of cyano, I didn't notice any fumes or steam. The video is a dramatic demo which does not represent reality when using this on models.

[Porcy Mane]

but what's the gas/smoke that comes off Given the propensity for CA glue to break down to cyanide, I'd rather know before trying this...?!

Exothermic reaction.

https://www.gluegun.com/blogs/news/most ... 20reaction.

Scroll down the page to exothermic.

P

[pete_mcfarlane]

Another vote for cyano and bicarbonate of soda.

Another useful surface filler is Tippex correction fluid. Apply it on to scratches etc, and then rub down. The stuff I bought recently seems to be non-solvent based and takes a few minutes to dry (unlike the kind we had when I was at school in the 1980s, which dried quickly and some of my classmates tried sniffing).

[Tilly]

This Vallejo variant is working well for me...

IMG_5351.jpeg

[bécasse]

Another useful surface filler is Tippex correction fluid. Apply it on to scratches etc, and then rub down.

I have used Tippex correction fluid in the past for replicating the steel plating sometimes used in the past to patch prototype panelled wooden carriage sides. It needs very careful rubbing down but the result is quite impressive.

[ClikC]

This Vallejo variant is working well for me...

I'll second this, I have been very impressed, which incidentally is like a slightly thicker tippex.