Suitable paint for 3D Prints

[2mmMark]

Apologies if I'm going over old ground, the search facility didn't come up with any results for the subject.

 

What do people find suitable for painting prints, specifically FUD from Shapeways.

 

On the recommendation of a member of the Narrow Gauge forum, I washed the prints in white spirit which cleaned them very well and also usefully turned them from being translucent to white.

 

My first attempt used Vallejo Acrylic primer which adhered very poorly to a print (after allowing several days for the print to dry after washing).  Fortunately, another dunk in white spirit allowed me to wash off the primer.

 

The next go was using Humbrol enamel - Satin 195 Dark Green.  This was going to be the basic body colour so I reckoned that as it's oil based, it ought to be a good bet. It was as the print seemed to absorb the colour. Three thin coats resulted in a nice solid covering which feels quite wear resistant. The first two coats dried a patch mix of matt & satin but the final coat gave a nice satin finish all over. I was brushpainting, by the way.

 

I then turned to another model and this time used Precision Paints BR Wagon Grey. Unfortunately this stayed tacky even after 48 hours. Using the white spirit technique (I'm getting good at this), the tacky paint was washed off and recoated with Humbrol Satin 156 Grey, with the same good results as above.

 

So, it seems like Humbrol might be the paint of choice for me. Once detailed and weathered, the stuff I'm painting will be matt varnished (Polly S matt varnish)

 

I should mention that I had previously painted a Nn3 brake van from County Rolling Stock with acyrlics and that was OK, paint's lasting well.  I don't know where CRS sourced their prints from.

 

What are other's experiences with painting?

 

It's a funny old material, isn't it?

 

Mark

[MGR Hooper!]

Apologies if I'm going over old ground, the search facility didn't come up with any results for the subject.

 

What do people find suitable for painting prints, specifically FUD from Shapeways.

 

On the recommendation of a member of the Narrow Gauge forum, I washed the prints in white spirit which cleaned them very well and also usefully turned them from being translucent to white.

 

My first attempt used Vallejo Acrylic primer which adhered very poorly to a print (after allowing several days for the print to dry after washing).  Fortunately, another dunk in white spirit allowed me to wash off the primer.

 

The next go was using Humbrol enamel - Satin 195 Dark Green.  This was going to be the basic body colour so I reckoned that as it's oil based, it ought to be a good bet. It was as the print seemed to absorb the colour. Three thin coats resulted in a nice solid covering which feels quite wear resistant. The first two coats dried a patch mix of matt & satin but the final coat gave a nice satin finish all over. I was brushpainting, by the way.

 

I then turned to another model and this time used Precision Paints BR Wagon Grey. Unfortunately this stayed tacky even after 48 hours. Using the white spirit technique (I'm getting good at this), the tacky paint was washed off and recoated with Humbrol Satin 156 Grey, with the same good results as above.

 

So, it seems like Humbrol might be the paint of choice for me. Once detailed and weathered, the stuff I'm painting will be matt varnished (Polly S matt varnish)

 

I should mention that I had previously painted a Nn3 brake van from County Rolling Stock with acyrlics and that was OK, paint's lasting well.  I don't know where CRS sourced their prints from.

 

What are other's experiences with painting?

 

It's a funny old material, isn't it?

 

Mark

Would love to see some pictures. And for the record on FUD I used acrylic with no issues whatsoever.

[Kylestrome]

My first attempt used Vallejo Acrylic primer which adhered very poorly to a print (after allowing several days for the print to dry after washing).  Fortunately, another dunk in white spirit allowed me to wash off the primer.

 

There is another another thread concerning problems using Vallejo primer here:

http://www.rmweb.co.uk/community/index.php?/topic/121328-vallejo-primerundercoat-74601/

so it may just be the primer that is causing the trouble.

[Guy Rixon]

I use Halfords spray primer, with acrylics for the top coat. I prefer Tamiya acrylics, but Vallejo are also good. However, I find that Vallejo paints in thin coats abrade off very easily, exposing the primer. I think they need varnishing to be properly robust.

 

I've read a suggestion that Halfords grey primer adheres better than their red primer when used on plastics or resins. I've used both and I'm not sure that I see any difference.

 

Bill Bedford reports that oil-based paints are damaging to FUD and FXD. Apparently, they soften the resin and degrade the surface. That suggests that a white-spirit wash would also be damaging, but perhaps it evaporates off before harm is done. I've used Humbrol enamels over Halfords primer on FUD prints and do not see surface degradation. I presume that the primer protects the resin if the primer coat is complete enough.

[billbedford]

The white bloom is caused by solvents washing out wax from the surface. It's preferable to seal the wax in with acrylic primer.

[2mmMark]

The white bloom is caused by solvents washing out wax from the surface. It's preferable to seal the wax in with acrylic primer.

 

If that is the case, I've not seen any surface degradation, softening or structural weakening of the print, either from the white spirit wash or the enamel paint.

 

When wet with white spirit, the translucency returns.

 

I'm now a bit puzzled as I thought the role of the wax was to support the print during the deposition process and the idea is to clean the wax off the print.

 

"...so while Samantha passes down the disks, the nice man holds the ladder while he cleans the dust and wax off in the dark..."

 

Mark

[rue_d_etropal]

I have not used enamel paints for many years, having switched to acrylics over 30 years ago, but I now actually use emulsion paint as most colours can be found. I still have my concerns about the plastic in FUD, long term(UV  effect), so WSF is my preferred material, especially as it can be painted with any water based paint. For all other plastic surfaces I always prime with a matt grey acrylic, and then paint with emulsion paint. So far no problems, but I suppose with a lot of handling it might wear off. Only negative is not being able to get some colours(BR green is one ), so use acrylic for that. Acrylic paint can damage some materia. My paint brushes(cheap ones) don't last that long, but are good enough for my work and don't cost much to replace(liquid poli glue will disolve dried acrylic on brushes if necessary).

For weathering I use the gunge washed off brushes. Cheap and simple.

 

Sometimes it is worth looking at the problem from another angle. I weigh up the pros and cons and base my decision on those, not just one. Everything is a compromise, and for any layout I am building, I look at the overall effect. It is one reason why I model in so many different scales, as each has its good and bad points. I enjoy a challenge and finding ways round problems. Sometims it it better to put that problem to one side and try a different route. I may not end up at the planned destination, but at least I end up somewhere.

[billbedford]

If that is the case, I've not seen any surface degradation, softening or structural weakening of the print, either from the white spirit wash or the enamel paint.

 

When wet with white spirit, the translucency returns.

If you dip the piece in to water you will get the same return of transparency. It is just the liquid filling the gaps in the granularity of the surface.

 

I'm now a bit puzzled as I thought the role of the wax was to support the print during the deposition process and the idea is to clean the wax off the print

It is true that there is a resin for the model and a 'wax' to support any overhang in the resin. However where the two materials are printed next to each other the two materials mix. If the 'wax' is removed with spirits what is left is a surface covered with microscopic spikes of the resin. This is the white bloom on the cleaned surface. 

 

Despite what you may have read on the Shapeways forum, the support material is not really a wax. It is a version of the same photo acrylic resin use for the build material, but engineered to give a lower melting point. One of the side effects of lowering the melting point seems to be making it more soluble in solvents.

 

I have found that a cycle of spraying with Halford's printer and then sanding until the surface is smooth enough to paint will give an adequate preparation.

[Steven B]

I give FUD parts a washing using normal household washing up liquid, followed by a scrub with a cream cleaner. Once it's been left to dry for a couple of days I then use Halfords primer, again leaving it a day or three to dry. I've not had any problems with either the primer or enamel top coats not sticking to the model. I've not tried acrylic paints but wouldn't expect any problems.

 

Might be worth trying a different primer?

 

Happy modelling.

 

Steven B.

[Quarryscapes]

Vallejo primer sticks fine to FUD, once it's clean - yours wasn't, it's that simple. CWRailways uses a Sodium Hydroxide solution to remove the wax, and it works very well - the parts are ready for paint, but because the wax is gone the print is much rougher. From Shapeways the wax fills up all the little crevices and cracks and the oil they use to wash the parts off makes the whole thing look shiny and translucent. I've been cleaning my FUD parts in aggressive thinners for years, started with a gentle clean up with a brush and now a few hours soak. I've had one set of parts soaking for months with no ill effect (other than taking on the colour oft he dirty thinner that I'd previously used to wash a brush!). 

 

One problem that has appeared with mine (and others') models over time is that the model goes glittery, anything from a few weeks to a few months after painting. This can be brushed off but feels greasy, this has happened with all types of finishing and painting techniques from etch primers to no primer, water or spirit bass and all variations between. 

 

I try and avoid FUD/FXD if I can, other materials are better to work with (but obviously the design and print characteristics need to be carefully matched to the application)

[2mmMark]

If you dip the piece in to water you will get the same return of transparency. It is just the liquid filling the gaps in the granularity of the surface.

 

I tried that on a white spirit washed print and it stayed white, except for a few tiny areas of framing/strapping where the surface texture is perhaps a little bit more open.

 

Vallejo primer sticks fine to FUD, once it's clean - yours wasn't, it's that simple.

 

Beg to differ. It was about as clean as I could make it, having been washed initially in warm water + Fairy liquid, ultrasonically cleaned, washed in white spirit, sanded in a few places and washed again in white spirit.

 

Anyway, I completed the painting on the loco a few days ago and it's dried out fine, with a nice even finish. Humbrol satin green body, satin grey cab roof and satin red buffer beam. I'm undecided whether to matt it down to a flat finish or simply leave it for now in case the glittery bloom appears.

 

The next job is a few wagons which will need to have a matt finish. Got to make the chassis for those first.

 

It's been an interesting experience so far. Thanks for the feedback and advice.

 

Mark

[Penrhos1920]

 

I try and avoid FUD/FXD if I can, other materials are better to work with (but obviously the design and print characteristics need to be carefully matched to the application)

Which alternate materials do you use and when?

[Quarryscapes]

Which alternate materials do you use and when?

 

BHDA mostly for complex detailed geometry on a single piece model, WSF Polished for big simple stuff that can be sanded or that is not visible, FXD for multiple small parts that can't readily be printed with supports. Lately most of my prints have been brass or bronze as I've been working in 16mm scale. 

 

 

^ BHDA

 

 

^ FUD Axlebox

 

 

^ FUD Axleboxes & Buffers

 

 

^ Old FUD Models where the Vallejo paint has clearly not stuck at all. 

 

 

^ WSF Building Skeleton.

 

 

 

^ Bronze brake standard

 

 

^ Brass fittings