Smoothing 3d printed surfaces?

[Verderer]

So I bought a couple of car models from Wargame Exclusive, and received them yesterday. They are otherwise quite nice, but immediately I noticed that many of the flat surfaces have these tiny layers of horizontal ridges which you can also feel by running your finger on them. I can only assume these are result of 3D printing which I understand takes place in such layers? And if they're not finished, they transfer to the cast final product?

Anyways, I am quessing that if I just paint on these, they will show clearly, especially with washes, so I guess I need to sand them down with fine sanding sticks / cloth etc? Any tips how to handle these?

I have observed some similar markings in some Zealot Dungeon doors, on some they're clearly visible, on some less so. So it seems there's a lot of variation between finishes, I guess some companies pay attention to these and try to remove them before casting, some dont'?

[beefcake]

I guess it depends on the resolution printed at. I've sold some 3d printed stuff for casting and sanding it is a pain, getting into tight spaces. Even when it looks like it is sorted, often it isn't.
You can buy stuff that smooths it. Never tried it myself but I imagine too much would get rid of detail. I'm surprised the Zealot stuff showed lines. I thought Eddie's printer printed at 8 microns. Could be wrong there.

[zemjw]

I had reasonable success with Mr Surfacer on a truck I printed at 100 microns.

I sprayed and sanded two or three times, and it definitely filled in the gaps. Sanding after each layer kept detail loss to a minimum, although it will depend on how much and what sort of surface detail you're looking at. Areas around rivets, eg, are likely to get clogged up more than flat areas 

I did buy a cast model that had what you are describing. The lines were visible, even though I couldn't feel them. Photos of the model showed it heavily camouflaged and weathered, and I'm pretty sure that was to cover the lines. In the end I took a similar approach.

Mr Surfacer comes in a number of thicknesses and a spray and brush on version. I'm sure there are similar substances out there, so it's worth looking into.

[Verderer]

I guess it depends on the resolution printed at. I've sold some 3d printed stuff for casting and sanding it is a pain, getting into tight spaces. Even when it looks like it is sorted, often it isn't.
You can buy stuff that smooths it. Never tried it myself but I imagine too much would get rid of detail. I'm surprised the Zealot stuff showed lines. I thought Eddie's printer printed at 8 microns. Could be wrong there.

Yeah, I bought a huge amount of the dungeon door etc. stuff from Zealot after the kickstarter, and to be fair, there were those print lines only in a couple of types, the ones with iron portucullis I think? Other stuff looked fine.

I thought about mr. Surfacer or similar but I haven't located a local source for it yet. I think it might be useful to prime the models first to see how bad they actually are, but the primers I use - Vallejo airbrushable stuff - aren't ideal for sanding. 

I don't relish sanding in any case, as with resin you need to be careful not to inhale the dust. So wet-sanding etc....

What about liquid green stuff? Never used it.

[zemjw]

liquid green stuff is more about gap/air bubble filling than smoothing and would be way too thick.

I'm not sure where you are, but Amazon has Mr Surfacer in the UK

I don't think a normal primer will help. The lines on the cast model I mentioned were still clearly visible after priming and painting.

[Wyrmalla]

It isn't always down to the resolution of the original print file, but also the state of the printer. For instance I picked up a Spectre miniatures BMP-1 recently and it was covered in print lines, and I doubt the resolution of that was inadequate.

To fix the issues with that model I first attempted to shave off the lines where possible. That isn't always an option as it could make a surface shallower than it should be.

Instead Games Workshop's Liquid Greenstuff can work. Where smoothed onto a surface that is, to allow it to fill the cracks. Followed then by sanding it. If just dolloped straight on though it will be too thick, and difficult to remove with effecting surrounding details typically.

However, of the two options, sanding is the easiest, even if it can mess with some of the details. Regardless, leaving the print lines there in the first place makes the model look horrible, so its a sacrifice that I've been willing to take, and usually the print lines are shallow enough not to cause too much of an issue for sanding.

[Verderer]

I am in Finland, so everything is a little harder to get... I can liquid GS easily enough locally, but mr. Surfacer I need to mail order. I found at least couple of retailers in Finland.

Can liquid sand be sanded easily? I seem to remember regular green stuff didn't take well to sanding...

[robh]

A couple of light coats of a gloss household varnish will fill in the step lines same as Mr Surfacer.
The thick DIY type not the thin Future/Floor cleaner type.
Brush on lightly and prop up the model to keep the area you want to fill level. Let dry well and repeat.

Not a quick fix but simple and effective.

[zemjw]

green stuff and liquid green stuff are two entirely different materials.

Liquid green stuff is basically really thick paint, more along the lines of artist modelling paste (I use Liquitex modelling paste now, as it's a lot cheaper than the GW stuff).

I never thought of trying it as a smoothing agent, good to know it works.

[Ultravanillasmurf]

Has anyone tried a Milliput slurry?

[Michi]

Has anyone tried a Milliput slurry?

Quite that, I used Revell putty and sanded that thoroughly (inevitable on the rounded cabins, I'd say):

[beefcake]

Has anyone tried a Milliput slurry?

Sounds tasty.

[grant]

I’ve heard anecdotally that leaving a bowl of acetone in with the model in an enclosed box will smooth surfaces.

Never tried it.

[carlos marighela]

I’ve heard anecdotally that leaving a bowl of acetone in with the model in an enclosed box will smooth surfaces.

Never tried it.

Beat me to it. There are videos on you tube showing the method. Supposed to be quite effective but like comedy, it’s all in the timing. Bought the acetone, never got around to trying ut personally.

[grant]

Beat me to it. There are videos on you tube showing the method. Supposed to be quite effective but like comedy, it’s all in the timing. Bought the acetone, never got around to trying ut personally.

I’m supposed to be getting my first 3D printed model soon, a life size SABOT round head; I am keen to try the acetone technique on it.