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A stupid question?


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Apologies firstly for what is probably a silly question...

 

When we (most of us) paint, the first thing we do is prime our models...

 

So why are the kits already coloured plastic?

It seems to me that there would be added cost in the injection moulding process to colour plastic for each kit. Why do the manufacturers bother?

 

I’m about to build a Sherman. The plastic in the box is olive drab already. I’m about to prime it grey. Then recolour it olive drab again. Why?

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Good question. All i can think is that some lesser modellers would not paint them, so they are at least in the correct colour ish. Seem to remember Airfix (i think) doing models in two colours years ago.

 

George.

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The answer to why paint something when the colour of the plastic is the same, is simple. The bare plastic has a waxy appearance, which sticks out like the proverbial sore-thumb on a finished model. If you want your subject to look like a toy, don't paint the plastic. If you want it to represent the real thing, start stirring those paint-pots. 

 

Chris.  

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20 minutes ago, spruecutter96 said:

The answer to why paint something when the colour of the plastic is the same, is simple. The bare plastic has a waxy appearance, which sticks out like the proverbial sore-thumb on a finished model. If you want your subject to look like a toy, don't paint the plastic. If you want it to represent the real thing, start stirring those paint-pots. 

 

Chris.  

Thanks for response but that’s not my actual question. My question was why do the manufacturers bother producing the plastic in a specific colour when they are intended to be painted. 

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Originally the likes of the Airfix tanks and figures were mainly aimed at Wargamers and then at model railwayers. 

Early Wargamers weren't fussed on painting up a tank, thus green for Allied, sandy-brown for German, blue soldiers for one side, grey soldiers for another side

Also certain colourants added to the main plastic alters the plastic hardness.

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Thanks. I can understand that colours in the mix would change the hardness of plastic. 
I’ve come to this hobby from years of collecting Lego so get that theory. The colour of ABS plastic lego is certainly a factor. Reddish brown lego is considerably more brittle than other coloured parts.

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Kids don't care.  Playing with the toys they would like to see the basic colour.  Remember the mass market overcomes picky specialist modellers.

 

I don't recall any Airfix kits in 2 colour plastic - except perhaps some of the large sailing ship kits with black rigging?  Matchbox used 2 or 3 colour plastic, specifically to attract the young.

 

One question: if it is already green, why paint it light grey before painting it green?

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52 minutes ago, Graham Boak said:

 

 

One question: if it is already green, why paint it light grey before painting it green?

Cos they don't do green primer?

I use primer to highlight defects, partilcularly joints or filled areas.

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As someone who worked in the injection moulding industry I can supply the right and simple answer to this one !

 Pigments are added to give a uniform colour.

In its raw state the plastic is quite opaque, but after going through the heating and injection process it tends to discolour slightly.

Then you have the added problem of miss shots being reground and added to the mix, you can only add a certain amount of regrind to virgin plastic

Colour pigments are also added to hide these variations and the stress and cooling patterns that appear when the plastic is moulded.

 

Hope this helps

Graham

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Sorry that I misinterpreted your original question.

 

In answer, I don't think that there will be any real "added cost" to moulding a kit in a particular colour. The raw plastic is supplied to the companies in huge bags of "pellets" of a certain colour. They are then heated up and injected into the moulds. I would take an educated guess that the bags would be a similar price, regardless of the colour. Would the same be true for the clear pellets? Admittedly, I just don't know.... Maybe more well-travelled folks than me can fill us in.  

 

Obviously, makers like Matchbox used the multi-coloured sprues as a marketing-tool to appeal to the kids, and I guess that there was also an implication with the sprues being in different colours that you could build the model and not have to paint it (if that's how you wanted to handle it). I would think that the "no-paint" option would be a very attractive one to the average 10-year-old (extra money for paints, brushes, etc. and the potential for getting paint everywhere....)

 

Chris. 

 

PS: This was written before I read the last response. That provides the most complete answer you could wish for.  

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44 minutes ago, spruecutter96 said:

Sorry that I misinterpreted your original question.

 

In answer, I don't think that there will be any real "added cost" to moulding a kit in a particular colour. The raw plastic is supplied to the companies in huge bags of "pellets" of a certain colour. They are then heated up and injected into the moulds. I would take an educated guess that the bags would be a similar price, regardless of the colour. Would the same be true for the clear pellets? Admittedly, I just don't know.... Maybe more well-travelled folks than me can fill us in.  

 

Obviously, makers like Matchbox used the multi-coloured sprues as a marketing-tool to appeal to the kids, and I guess that there was also an implication with the sprues being in different colours that you could build the model and not have to paint it (if that's how you wanted to handle it). I would think that the "no-paint" option would be a very attractive one to the average 10-year-old (extra money for paints, brushes, etc. and the potential for getting paint everywhere....)

 

Chris. 

 

PS: This was written before I read the last response. That provides the most complete answer you could wish for.  

The pellets would normally be supplied as "virgin pastic" that is with no colour, and for most companies in bulk, rather than bagged.

The pigment is added during the mixing stage where other additives, (Like Zinc Stearate) are added to the mix.

As an addition to this, zinc stearate is added to lubricate the plastic on it's way through the extruder, because most injection moulding is automatic now, release agents are sprayed onto the tools at regular intervals to aid separation. if you ever get problem painting your kits, it's probably because of these release agents, which are basically a silicon based spray.

That is why I always wash my sprues !

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I don't think that kit manufacturers are necessarily intent on producing a kit in a particular colour. I have two versions of the same kit, both from Italeri. Both are Crusader Mk.l's. One is in an olive green colour, whilst the other is grey.

As for priming the model. I, and most other model builders, do it to give the top coats something to bite on. Some model paints, if sprayed/brushed onto a plastic surface, can easily be rubbed off.

And the question about why don't the paint manufacturers supply the colours in gloss, one of them does, or at least, did. I've got dozens of tins of aircraft colours from Extracolour from the days when I used to build them wingey things. I don't know if they're still available.

 

John. 

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Xtracolour still provide their paints in gloss.  Colourcoats are in satin because of  survey carried out before starting production and that was the most desired. 

 

In over 60 years modelling I've never primed and never had any paint rub off easily.  But then I don't use water-based acrylics, and rely upon more than one coat to find flaws/cover fillers etc.  Come to that, I don't usually wash my sprues before painting, either.  But then I don't enter competitions - I suspect most other modellers don't, either.

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1 hour ago, Graham Boak said:

Xtracolour still provide their paints in gloss.  Colourcoats are in satin because of  survey carried out before starting production and that was the most desired. 

 

In over 60 years modelling I've never primed and never had any paint rub off easily.  But then I don't use water-based acrylics, and rely upon more than one coat to find flaws/cover fillers etc.  Come to that, I don't usually wash my sprues before painting, either.  But then I don't enter competitions - I suspect most other modellers don't, either.

Lacquer based paints are less reliable on a primer for a good coat. Acrylics tend to need one to adhere properly.

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On 3/6/2021 at 2:43 PM, Graham Boak said:

Xtracolour still provide their paints in gloss.  Colourcoats are in satin because of  survey carried out before starting production and that was the most desired. 

 

In over 60 years modelling I've never primed and never had any paint rub off easily.  But then I don't use water-based acrylics, and rely upon more than one coat to find flaws/cover fillers etc.  Come to that, I don't usually wash my sprues before painting, either.  But then I don't enter competitions - I suspect most other modellers don't, either.

  What paints do you use.

I am toying with the idea of not using primer and just putting my Tamiya Acrylic straight on.  I dont really want to use Motor Discount Store primer as it's so thick.  I only use brushes.

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I usually use Tamiya Nato Black as a primer, but i do use an airbrush. Never had a problem and dont see that a specific named primer paint is needed.

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I have used rattle can Citadel Chaos Black primer, having come across this when my youngest son got into Warhammer.  It sprays finely and adheres well. I made what turned out to be the mistake of buying a Vallejo rattle can black primer.  Mistake because it sprayed far too thickly.  Citadel rattle cans are now available in more colours and the others I've tried seem to work just as well.

 

But most recently I've been using Army Painter rattle can Leather Brown.  This sprays well too and is a better base colour for armour plate should you get wear-through during handling or be using salt, chipping fluids etc.  There is nothing more annoying than bare plastic peeking through.

 

As for plastic colour, I find grey easiest to work with and see what you're doing, and darker green hardest.  Grey seems to show the detail better.  Sandy is OK.  But you get what you get in the box........

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On 11/03/2021 at 21:43, Timn said:

  What paints do you use.

I am toying with the idea of not using primer and just putting my Tamiya Acrylic straight on.  I dont really want to use Motor Discount Store primer as it's so thick.  I only use brushes.

I can vouch for Halfords rattle can black bodyshop primer. Looks thick when it goes  on but dries beautifully smooth and even.

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On 3/6/2021 at 1:04 PM, Test Valley Models said:

 Pigments are added to give a uniform colour.

In its raw state the plastic is quite opaque, but after going through the heating and injection process it tends to discolour slightly.

Then you have the added problem of miss shots being reground and added to the mix, you can only add a certain amount of regrind to virgin plastic

Colour pigments are also added to hide these variations and the stress and cooling patterns that appear when the plastic is moulded.

 

Anyone curious to know what the plastic looks like without pigment has only to look at an old Skybird 86 kit.  I think that on at least some of his mouldings Mike Eacock used a fair bit of regrind and no pigment because the quite psychedelic patterns in the plastic drew comment at the time 

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On 06/03/2021 at 14:16, Test Valley Models said:

The pellets would normally be supplied as "virgin pastic" that is with no colour, and for most companies in bulk, rather than bagged.

I used to handle the plastic pellet imports for Lesney from BASF, Described as 'Polystyrol'  and came pre coloured in various shades, or clear.

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Just now, bentwaters81tfw said:

I used to handle the plastic pellet imports for Lesney from BASF, Described as 'Polystyrol'  and came pre coloured in various shades, or clear.

 

If companies are using a large amount of a particular colour then it can be ordered in standard batch colours

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