To undercoat (and when), or not to undercoat?

[Guest]

Building 1:72 Airfix WWII aircraft, thinking matt black undercoat might work, help bring the colours down (using "starter kit" paint set) - is this necessary or even just useful?

Do I spray whilst still on the sprues?

Would appreciate the advice, as I'm about to do a Hawker Typhoon, and hope to make it my best yet....

[eddiesolo]

Hello Alister and welcome to the forum. I tend to undercoat all my models-just to give a good key for the top coats. If the model is to handled then a undercoat helps give a more hard-wearing surface. Some folk just give the model parts a good clean-pre-shade and then top coat with a laquer coat to finish.

Spraying on sprues is a question that only you can really answer, it is what you feel comfortable with. I tend to spray on the sprue but it is down to my disability and easier for me to keep a track of stuff. Many folk like to assemble, fill any gaps, sand and then undercoat, then once dry apply the top coat.

The paints supplied in the starter kits are not the best so if you are investing time in assembly, masking, undercoating etc then maybe a few quid on some better paints will get you better results.

Si

[Alan 45]

I only undercoat pe, never on plastic I find it can fill panel lines and small detail so I just wash it , I used to paint on the sprue but if you get a kit that's ill fitting you might find you have to fill the gap so that can ruin a build

There is no right or wrong way it's however you want to do it

[stona]

Undercoating has been covered so I'll just suggest that you don't use black. I'd suggest the reverse, white or the ever popular grey.

On a small model like 1/72 you actually want to lighten the colours to make them look realistic and a very dark primer will have the opposite effect, darkening them and reducing contrast.

Modellers tend to lighten due to a phenomenon called scale effect, don't beat yourself up with the minutiae of lightening ratios etc which are sometimes like being in a school science class, just try to appreciate the theory behind it. Maybe add an unscientific 'splosh' of white to your colours if you fancy it. It's up to you

Cheers

Steve

[eddiesolo]

Agree Steve, totally forgot about scale effect. In a nutshell: the paint particles used in painting/spraying are a uniformed size but the model isn't, so a light grey used on a 1/24 scale would look darker on a 1/72 scale due to how light is reflected etc from distance. I think I have that right...

This effect affects all models and scales but people like Stona and others who specialise in aircraft will be able to offer the best advice on colours, shading etc.

Si

[stona]

It's really about our perception of colours. When looking at a model you are looking at a small thing close up. You are trying to represent how you see a large thing further away (Father Ted would be proud of me). Without going into the physics of the effect, lightening the colour on smaller objects helps to fool our eyes, or our perception. It helps to make the model less toy like and more realistic, as do many of the tricks we try!

I'm sure a google of 'scale effect' will lead to all sorts of very complicated and scientific discussion by the sort of modellers who have a colour wheel in their tool box. That's all well and good, I'm a firm believer in each to their own, but it doesn't float my boat and you don't need to understand all that stuff. It's more important to experiment until it looks right to you. It's your model after all!!

This is supposed to be fun. The most important thing is to enjoy the hobby, not fret about whether you should add 10% or 15% of white to a particular colour

Cheers

Steve

[eddiesolo]

Funnily enough I found this:

• 1/32 - add 7% white
  
• 1/48 - add 10% white
  
• 1/72 - add 15% white
  
• 1/144 - add 23% white
  

No idea if this table is still relevant, and as Steve points out it can get too technical and spoil your experience. Have fun.

Si

[stona]

I believe those percentages have derived from Huntley's work years ago.

It is only fair to point out that some people think the whole thing is a load of b*llocks and don't bother at all. As I said, each to their own. I do usually lighten my preferred paints slightly, but not precisely and I've never worked out a percentage ratio

Cheers

Steve

[PaulTRose]

i always prime my models (and give the parts a good wash first whist still on the sprues to get rid of any release agent) as it gives a good surface to put the colour coat on. it can also have an effect on the colour coat dont forget..........i made the misake recently of using a grey primer for a red colour coat......came out dull....redid it with a white primer and got it bright like i wanted

as for priming on or off the sprues.........i do both, all depends on what the model is

for example, when i do a bike it all gets primed on the sprue but then everything gets taken off for its colour coat

im currently doing a tank so it got built, then primed as the primer shows up any gaps, etc

[aaron]

I prime every model, a habit I picked up when I started using acrylics.

Armour pieces get black or hull red whilst aircraft gets grey with black preshade.

Each to their own, people find what works for them.There is no right or wrong technique...beautiful hobby.

[Guest]

I use acrylics mostly, and prime everything. I use white primer, as it gives a better contrast with any pre-shading, and because spraying light colours over anything else doesn't work well for me. Another good reason for priming is that it shows up any blemishes before you start on the top coats.

[Guest]

For me definitely a primer. Filler will give a false impression and tell me I have made a perfect job some times near and some atrocious.

Primer also makes a solid background and obliterates filler and all the other things which stand out.

I use Vallejo and a mist coat then a full coat after correcting poor filled parts gives a perfect base for the final coats. Plus using a primer which gives a colour which obliterates the basic colour of type grey plastic.

Also. With a lighter shade of primer I have found that with a slightly patchy top coat a good effect can be had with the primer shining through a thinner part of the top coat.

On the Merlin Airfix at the moment with a mist coat and full primer coat I cannot say that the panel lines are lost certainly not at 1/48. If anything the reproduced lost lines actually benefit as the lines are more rounded.

Most important I have found is to make sure that the primer is cured. Using Vallejo Primer I cannot wet and dry for say 36 hours with out pulling the primer off in small areas. Plus do not go mad just put on enough primer to cover and give a medium depth. The primer is essentially to give a coat to stick to the plastic. The coats that follow easily stick to the primer and provided the primer has essentially cured the following coats will quickly dry.

Laurie