Clear primer over coloured plastic before weathering with acrylics?

[murphaph]

Hi all,

I've noticed acrylic weathering paints applied with the airbrush can be relatively easily scratched off models that employ coloured plastic rather than having a painted finish. Is there such a thing as a clear primer to provide a key for the weathering paints? Or can I just use a matte varnish? Anything specifically for this in the Vallejo range?

 

Thanks!

[john new]

I have used dilute PVA for years as a primer for water based paints over plastic. 

[murphaph]

Thanks Jon I shall give that a go. Just diluted down to milky consistency and airbrushed on?

[john new]

I’ve only done brushing, at a mix diluted slightly over a 50:50 mix, probably about 33:66 (one spoon to two). Got an air brush set 2nd hand at the recent SWAG do but not yet tested it to start my learning curve.

[hayfield]

I have in the past used rattle can primer, if coloured plastic is more of an issue perhaps the etched primer may be of use ?

[Oldddudders]

I'm not sure PVA, albeit diluted, and an airbrush sounds like a healthy combination. The result might be great, but cleaning the airbrush at once would seem prudent. 

[murphaph]

Yeah for sure, but I guess the same goes for anything you spray through an airbrush. I might just try Vallejo acrylic matte varnish next time. These are cheap Lima goods wagons for my son. They used a lot of smooth coloured plastic rather than painted finishes so there's nothing for the weathering paints to really bite to.

[murphaph]

Has anyone tried just using Future/Klear to prime bare plastic? It sticks to floors so I guess it would stick to plastic too? Might be better for the washes to run into the little crevices too if it provides a key.

[Campaman]

Klear is OK for washes as its a gloss finish, but you need matt for powders to stick which is what some weathering paints are, just powders in a solvent/fluid carrier.

[boxbrownie]

2 hours ago, Oldddudders said:

I'm not sure PVA, albeit diluted, and an airbrush sounds like a healthy combination. The result might be great, but cleaning the airbrush at once would seem prudent. 

You can buy a water soluble PVA as used in schools, even dried up completely it will wash away after a good soaking.

 

It would still work as an undercoat/primer.

[Quarryscapes]

Many, if not all, automotive plastic primers in rattle cans are clear

[murphaph]

Cheers Quarryscapes but I have moved away from rattle cans. I spray at a spray booth, indoors and no matter how clean I keep it, I found rattle cans caused so much turbulence that dust would invariably be kicked up and land on my models during spraying. I do everything with the airbrush now, including priming so I'm looking for a strictly airbrush based solution. Having said that, I see Vallejio has a clear base coat for RC cars which is probably similar to automotive applications. I could try that. I need to get some more Klear (or a local equivalent as Klear is not available here) and try that first I think as it is cheap and if it works would be very economical.

[ISW]

16 hours ago, murphaph said:

Is there such a thing as a clear primer to provide a key for the weathering paints? Or can I just use a matte varnish? Anything specifically for this in the Vallejo range?

 

Why not use Vallejo Primer? Yes, I know it's not clear, but it must (?) be designed for use with Vallejo acrylics. I recently tried some, and it sprayed on without issue. No reactions to overcoats of acrylics.

 

Ian

[ianLMS]

I use Alclad II products through my airbrush and have had success with their Aqua-Klear products. They also do primers which I haven't tried yet but plan to as it is much more controllable than rattle can primers. 

 

Test on a scrap piece before using on an expensive model mind in case it reacts. I haven't had any issues with my self-painted kit loco's but you never know.

 

https://alclad2.com/

[murphaph]

Thanks guys. Ian, I have normal grey and white Vallejo primer but I don't want to actually paint these wagons. They are coloured plastic with tampo printing details. I just want to apply weathering acrylics to dirty them up, so any primer must be clear. I probably wouldn't care on my own models but these are more like toys and get a lot of handling so the weathering needs a bit of help sticking.

[ISW]

11 hours ago, murphaph said:

They are coloured plastic with tampo printing details. I just want to apply weathering acrylics to dirty them up, so any primer must be clear.

Ah, my mistake.

 

In which case, why not spray with a Vallejo varnish? There's Gloss (70.510), Satin (70.522), and Matt (70.520); and there's probably some more. I've bought one of each, and plan to use them on my buildings once I've finished with painting / weathering.

 

Ian

[murphaph]

Yeah that's really my question I guess....will the Vallejo varnishes take to the bare plastic as a primer does?

[ianLMS]

The Alclad Aqua-Klear are clear products and I use the matt one to protect the paint/transfers before applying weathering powders and washes etc.

[Campaman]

For clear varnishes I use artists acrylic type namely Windsor and Newton Galeria from the Range, far cheaper than any modelling type, I spray it through a 0.2mm or 0.3mm nozzle thinned slightly with water, available in bottles up to 500ml in Gloss, Matt and Satin, sticks to plain plastic fine and over paint finishes. I only bother with the Gloss and Matt and mix my own Satin from the gloss and matt.

 

[murphaph]

That sounds like a really good tip with the Galeria varnishes Campaman. A bit of googling shows many satisfied modelling customers. Seems the matt is really flat too. I will definitely be giving this a try.

[boxbrownie]

14 hours ago, murphaph said:

That sounds like a really good tip with the Galeria varnishes Campaman. A bit of googling shows many satisfied modelling customers. Seems the matt is really flat too. I will definitely be giving this a try.

That’s odd, as I used the flat Matt version on my base “ground” coating of paint and grit and I still wasn’t happy with the matt finish, still had a bit of a gloss to it, looked like it had rained recently.

[Campaman]

The matt needs a real good shake and stir as the matting agent settles at the bottom. I have tried other matt varnishes and find the Galeria to be one of the best.

[boxbrownie]

18 minutes ago, Campaman said:

The matt needs a real good shake and stir as the matting agent settles at the bottom. I have tried other matt varnishes and find the Galeria to be one of the best.

I know, it was given the mixing of its life…..I have a stirrer on my mini drill 😁
 

It might have been an odd batch mix.

[Hal Nail]

On 10/05/2022 at 15:46, murphaph said:

Yeah that's really my question I guess....will the Vallejo varnishes take to the bare plastic as a primer does?

As I have pointed out many times before, when asking a question on RMWeb, it really helps if you already know the answer, then you can more easily skip all the guesses and irrelevant stuff :) 

 

Have just painted a scrap of shiny plastic in Vallejo primer, gloss and matt varnish out of curiosity. Suspect none will stick very well but i'll let you know.

 

Edit: results now in. I had a scrap of very shiny plasticard that just happened to come supporting some etched parts the other day. I didn't attempt to clean it but did a quick patch of Valejjo acrylic resin matt, and gloss and grey surface primer.

 

The matt varnish was probably the thinnest coat but scratched off very easily with a fingernail (although I'm impressed with the quality of the matt finish!). The grey primer is tougher but does mark a bit. The gloss i cant move at all although there is less key for a finger nail to grip.

 

Anyway for what its worth I'd degrease them then waft gloss on first then matt or satin as desired on top.  

 

 

 

 

Edited May 17, 2022 by Hal Nail

[murphaph]

That's a nice little experiment! Much appreciated.