RAL and NCS colours for modelling

[Giugiaro]

Today I went on a quick search for RAL colours to use in modelling, as I have a few second hand coaches in need of repair, and a few 3D printing coaches in the making.

 

Colouring these is easy because I have the RAL K7 Classic references for the colours, but I got into trouble when finding matches in the market.

 

Revell has a very limited selection of RAL colours.

Montana Colors has plastic primers and RAL sprays, but their collection of RAL colours is even more limited.

Tamiya has their own colour system and ships to Portugal, and, so far, their collection is also very hit-and-miss when it comes to RAL matches (not officially endorsed).

 

None had NCS references so it's going to be even harder to work on older, pre-RAL rolling stock.

 

I'm wondering: When it comes to painting in modelling, is there a way to use the same, or similar, approach to what we do in the railway industry?

Would the paints and varnishes used for coating rolling stock work for models if we use a proper plastic primer?

[Martijn Meerts]

I don't know about railway paints, but automotive paints for example could theoretically be useable. They'd need to be thinned down quite a bit for airbrushing of course, and you won't really be able to use any of the more special stuff like metallic or iridescent paints.

 

For varnish / clear coat, I'd just use standard hobby stuff.

[cteno4]

I think it’s also a matter of pigment particle size. I’ve been told the finer modeling paints generally have smaller pigment grains to get a more even pigment coat with thin passes. some cheaper paints have much larger pigment grains and one of the reasons they don’t airbrush well and tend to gum up more in the airbrush.
 

My guess would be auto and train paints have larger pigment grains.

 

jeff

[brill27mcb]

Yes, Jeff, I remember old Floquil ads that highlighted how finely their pigment was ground.

 

Rich K.

[Martijn Meerts]

12 hours ago, cteno4 said:

I think it’s also a matter of pigment particle size. I’ve been told the finer modeling paints generally have smaller pigment grains to get a more even pigment coat with thin passes. some cheaper paints have much larger pigment grains and one of the reasons they don’t airbrush well and tend to gum up more in the airbrush.
 

My guess would be auto and train paints have larger pigment grains.

 

jeff

 

True, although for the higher quality modern automotive paints, the pigments are fine enough for airbrushing. A lot of the custom airbrush work on cars uses the same paint as the rest of the car, just thinned down.

 

Overall though, it's definitely recommended to use model paints for models. Should be possible to find some conversion chart from RAL to matching / close to matching paints. Vallejo has a very good selection of colours, and their paints are really good quality too.

 

[bill937ca]

This is the RAL color scale.  Text is in Italian.

 

https://ral-colori.it/

 

A couple of examples.

https://ral-colori.it/mazzeta-ral-classic/tonalita-di-rosso/ral-3020/

https://ral-colori.it/mazzeta-ral-classic/tonalita-di-giallo/ral-1023/?fbclid=IwAR20rfMReqH5jJtMOg2IxNBdK2QHnWuefRHUr3FxGaIyZm_qpQDz98IawX0

 

RAL Color Chart for Machinery

https://www.howarequipment.com/products/tables_and_charts/ral_color_system/

Edited October 26, 2022 by bill937ca

[cteno4]

16 hours ago, Martijn Meerts said:

True, although for the higher quality modern automotive paints, the pigments are fine enough for airbrushing. A lot of the custom airbrush work on cars uses the same paint as the rest of the car, just thinned down.

Yep that true. But I still wonder if on small models and thinner coats of car paint may still have particles big enough not to give a nice fine coat.

 

i remember having this conversation with someone a number of years ago who was very knowledgeable on paints and getting the skinny on all these details and the only thing coming back to me today was pigment particle size! Age sucks.

 

jeff

[Martijn Meerts]

Yeah, it also depends on the brand of the paint. Some just have a very fine particle size, even in things like automotive paints. On the other hand, quite a few of the really cheap hobby paints have particles that are really too big for anything above like 1/12 scale or something 🙂

 

And yes, age sucks, especially when your mind is convinced you're still 16, but your body is just going 'nope' all the time 😄

 

[Giugiaro]

Well, I have a sacrifial H0 coach that I can use for experimentation.

 

If anything goes wrong, at least nothing of worth will be lost.

 

I'll try a normal modeller plastic primer, then I'll try using the paints we use for our prototype coaches, and see if there's any ill reaction.

[Giugiaro]

Small update: The coach was primed with Montana Colors' Transparent Plastic Primer.

Weirdly enough, the primer developed a coat of micro-bubbles on application, that seemed, at first, that the coat was going to be a disaster.

 

A weekend later the primer turned out to be OK, although it did leave a textured look akin to that of hammered sheet metal.

 

My colleague, from the coating department, said that the bubbles might have been a result of plastic dust, still settled in the surface of the model, that made the hydrocarbon gases in the primer to emerge spontaneously.

 

Edited January 13, 2023 by Giugiaro

[cteno4]

9 hours ago, Giugiaro said:

My colleague, from the coating department, said that the bubbles might have been a result of plastic dust, still settled in the surface of the model, that made the hydrocarbon gases in the primer to emerge spontaneously.

Interesting, always great to hear these little tidbits from a professional! 

jeff

[Giugiaro]

I had a go with the Montana Colors RAL sprays. This time I tried a direct paint without the plastic primer on a KATO Chibi Loco.

 

While the brown RAL 8017 behave incredibly well, covering the surface in just one single pass and thinning out uniformely as it dried, the yellow RAL 1021 was a complete disaster.

 

With the same preparation as the brown, the yellow was incredibly watery and transparent, it clumped in the corners and holes, and bubbled quite a lot when drying.

I had to file the corners back into shape, and sand off the excess paint.

 

I was told to try again using the yellow with three quick passes, but I'm very nervous about the bubbling and unneven coat. It might just ruin the Chibi Loco altogether...