Painting FUD/FXD

[C855B]

Given a recent big investment in FXD output, I have more concerns than the usual "fear of painting". In other forii there are reports of issues with some paints on Shapeways' high-resolution resins including peeling and uncured resin bleed-through. So it's time to consult the experts    for their experiences.

I have Scalecoat I and II, Vallejo and TruColor on hand. My concern with Scalecoat in both flavors is it may be too thick by the time it covers, which has been my experience so far. Vallejo seems to work well on a couple of small tests I did on FUD... for that matter, I can't get the stuff off, even scraping with a fingernail. OTOH, there was discussion on the Shapeways' forum about Vallejo peeling. Then I have concerns about TruColor's acetone solvent, with reports that acetone dissolves or weakens FUD/FXD resin under some circumstances.

Also, there are signs of uncured resin on the FXD shells I received. You can see them here, the dark areas on the sill and cab, even after several hours in Bestine:



I will try one of the recommended tricks of doing additional post-curing with a UV light and see if it makes any difference.

More or less I'm answering my own question - post-cure, and use the Vallejo (and get it over with!). But I'm resisting the Vallejo a little because of the custom color mix required for railroad colors, where tomorrow's mix won't match today's, even with the best of measurement.

[Philip H]

most of my FUD painting (I haven't done FXD yet) has been small scale parts and loco cabs.  Because of expediency (read I'm chaep and sometimes lazy) I painted them all with Rustoluem grey primer first.  Seems to be sticking well so far - and made doing an SBD BQ23-7 easy because its a close match to SBD grey.   

[towl1996]

+1 for the gray primer. Has worked well for me thus far.

[C855B]

Velllly interestingk. The pigment on the DIY-store Rustoleum is fine enough for models? And still covers? The one I primered (on Weekend Update) was with Tamiya gray primer, and by the time it covered it was starting to get detail fill-in.

I think I'll run more tests. I have a couple of scrap shells in FUD from a previous project, so can try a few things with those.

[Philip H]

Like I said I've done cabs that way and some other parts. Can't speak to a whole shell.

[bnsfdash8]

When I paint FUD or FXD I prime first (usually Tamiya primer or Krylon) and then paint like normal after that's dry. I used tru color on my C39-8 and GP9B, both in FXD, and have yet to see any kind of issues with the paint on them.

[sd45elect2000]

I primed the shells with either Testors or Floquil primers. I then sanded the shells smooth. I used a few different finish paints. The Electroliner is painted with "One Shot" sign paint over the sanded Floquil primer. The top coat is Testors semi gloss thinned with lacquer thinner.

The conventional North Shore car is primed the same way and sanded smooth. The roof is Scalecoat 1 sand mixed with a little white and yellow. The carbody is a mix of Scalecoat 1 paint mixed to suit the North Shore paint chips. The top coat is Testors dullcoat.

I also used some Tru Color SP scarlet on some other North Shore cars with good results.

Randy

[towl1996]

In an attempt to eliminate the banding effect, without sanding, I tried Mr Surfacer primer and applied it too thick and it started to cover the details. Since then, I've been sanding as much as possible and using regular primer and it's turned out fine, not perfect. I guess I could try the Mr Surfacer again and see if the results are better. But a lot depends on the orientation of the printing and where the banding shows up. There seems to be a lot of moving parts in this puzzle.

[sd45elect2000]

One other thing I do to take off the "fuzz" especially around windows is to use a brass wire brush to help smooth things.

 I haven't found any method other than priming and sanding to get rid of the banding effect. The payoff was that the Electroliner turned out glass smooth.

Randy

[Lemosteam]

I have found that the Bestine soak does not complete the process.  I use an inexpensive ultrasonic brush and dish soap to remove any remaining artifacts. Of course this is difficult with small parts.  I have also used my air eraser to clean up detailed areas that the brush cannot get into, unfortunately it still does not eliminate the banding as was my original hope.

I really can't get over how porus the FXD and FUD is, I have triple coated with dullcote with a brush and all thre were absorbed completely.

All ove the above was done on the sand dome in this picture:

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[C855B]

I have found that the Bestine soak does not complete the process.  I use an inexpensive ultrasonic brush and dish soap to remove any remaining artifacts. Of course this is difficult with small parts.  I have also used my air eraser to clean up detailed areas that the brush cannot get into, unfortunately it still does not eliminate the banding as was my original hope.

I really can't get over how porous the FXD and FUD is, I have triple coated with dullcote with a brush and all three were absorbed completely.
...

Valuable insight, John. My procedure has been a power toothbrush with Bestine (and much ventilation), then follow with the toothbrush dry (for the fuzz). I'll add the detergent scrub to the process.

Yes, I've also been amazed how porous it is. To a certain degree this isn't a bad thing - once applied to a fully-cleaned surface, that paint is going nowhere. Heaven help you try to strip it if you screw something up, tho'. 

Incidentally, 12 hours under UVA lights did nothing for the dark areas on the shell.

[Lemosteam]

That just means the material is trapped. It should not be an issue.