Airbrushing Primer or Filler

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PostPosted: Sun Jun 13, 2021 3:25 pm
TL;DR: I want to use automotive base layer for plastic scale models. I don't know what to buy. It needs to be very fine particles

(Disclaimer: I am a noob, so I imagine I will be using the wrong terminology here. When I say primer I mean 1. the layer that the paint will stick to 2. the layer that will show me where my putty work needs corrections 3. Filling out my 1500 grit sanding)

Hi, I just registered to ask this off topic question, so feel free to ignore me :) Although I hope it is OK for me to leech a little off of your accumulated wisdom

Back story:
I build models from 12" inches (30cm) to 35" (90cm), they have very fine details

I am getting tired of buying primer in 40ml jars (yes, 0.16 Cups) for USD 7.5 so I want to switch to automotive paints. But I get confused when I read about all the different kinds.

I found two primers, one is described as "Acrylic 2K Primer" the other as "2K Epoxy Primer".

The first contains
xylene
bisphenol-A-(epichlorhydrin), epoxy resin (number average molecular weight 700-1100)
methyl methacrylate
2-hydroxyethyl methacrylate

The second:
bisphenol-A-(epichlorhydrin), epoxy resin (number average molecular weight 700-1100) reaction product: bisphenol-A-(epichlorhydrin) epoxy resin (number average molecular weight =< 700)
Fatty acids,C18-unsatd., dimers, reaction products with N,N-dimethyl-1,3-propanediamine and1,3-Propanediamine

How do you guys find your way through this jungle? I can't really ask advice for specific products, because they would not be available here in Danmark, and I could not find any forums like this in my country?

I read an article telling me that I need automotive acrylics, as they adhere better to styrene. And I have bought an adhesion promoter for plastic. But in the modelling world there is much confusion about paint types. Acrylics are mostly used as a name for water based paints and lacquer for cellulose based paints. I find it overwhelming, starting from scratch trying to understand all this :flatten:

I don't even know if I have stated my questions in a clear manner...



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PostPosted: Sun Jun 13, 2021 10:52 pm
i'm wondering if you could use some hi build 2 part primer. you would need to reduce it considerably and apply SEVERAL coats to get some build. i would stay away from epoxys although a good product its somewhat hard to sand and might be difficult for you to work with. you should consider maybe getting a detail gun , just a step up from an air brush and can handle heavier based paints more easily and still spray a fine pattern please post some pictures. i got my start model painting. post some pictures and tell me how and what your doing and with what.
Jay D.
they say my name is Jay



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PostPosted: Mon Jun 14, 2021 5:20 pm
I just started out, so have only finished one model. But here are some of hte models I working on:

https://imgur.com/a/XINuyRw

My airbrush is this one

https://imgur.com/a/WQ00tm1

It has a fairly big 0.5mm nozzle, much bigger than normal .5 airbrushes. The taper on the needle is very steep. And it is a fan pattern nozzle. About 2 inches wide at most. But suitable for models I think

As I understand there are no mini paint guns that can run on an airbrush compressor. Mine only puts out 23L per minute (0.8 CFM) and I live in an apartment. If you know of one I would be very exited.

My problem arises when I go to web shop and start looking at primers.

Ideally I need something that has

- A satin finish, not rough. The next coating of paint needs a smooth surface for the paint to flow into all the small channels.
- It needs to resist cellulose lacquers, because those are what I use for colors.
- Covers although the layer is thin (I am thinking below 50microns?) so it does not hide the details

There are so many formulas and I think I need to learn some keywords to identify the right product.

When you say "hi build 2 part primer" that is not epoxy, you are hitting the nail on head here. Because that is my problem, what exactly is this unobtainium called? Is is Urethane or acrylic or something else. Can you give me some identifiers?

I can link to some affordable stuff I can buy locally:

https://www.chamaeleon-produktion.de/id ... er-41.html
https://www.chamaeleon-produktion.de/id ... r-1-l.html

Is this what you are talking about?



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PostPosted: Mon Jun 14, 2021 6:54 pm
i'm thinking you would call it a urathane 2 part primer, its a primer with an activator. we have to be careful here you guys talk different than we do, so some things could get confusing. i know i said hi build but you may be better off just with a std. primer. you'll have to make the call on that. the hi build might be more versatile for build and as a sealer for a smooth finish. be sure to get the product info sheet that tells you about dry times an mix ratios, recoat times and so on. you say your going to use lacquer as top coats. most 2 part primers should tolerate lacquer BUT your going to have to be careful some paint products don't like lacquer. i would always test it on something, when doing your priming do a scrap piece the same way then when it comes time to top coat do the scrap part first and see what it does. your gun should be fine. the first one on your list it mixes 4-1 the 444 i would investigate that. i have no idea i've never seen it before so i can't help all that much other that it mixes like ours do .
Jay D.
they say my name is Jay

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PostPosted: Mon Jun 14, 2021 8:37 pm
Just a few thoughts.....

If OP lives in an apartment, using 2K products maybe isn't such a good idea. Would need setting up mini booth and proper exhaust system, albeit small. Plus you'd still have a certain amount still in the room.

If I was doing something like he's doing I'd start with a single coat of adhesion promoter over the plastic body. Then go to two light coats of 1K acrylic primer. Easily thinned and, in theory, could be applied with a big airbrush. Low solids content won't interfere with detail on the bodies. Not highly poisonous, although an exhaust and mask is still a good idea. If you put it on right it will be smooth and flat, needing no more than a little rub with grey Scotchbrite to prep for colour. It won't react, like some 2Ks, to the thinners in the colours, although not overwet coats are better.

I have an airbrush but for small jobs I use a Star S2 mini spray gun. Mine has the 0.8mm tip, but they do come in 0.3mm and 0.5mm sizes as well. Link to example is here. Anest Iwata also make some really great small guns.

In terms of little compressors, there are small ones that are big enough to run a mini gun or airbrush. I think that these are ideal. Super quiet, light and yet big enough to do that job. You should be able to find something similar where you live.
Chris



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PostPosted: Mon Jun 14, 2021 10:48 pm
:goodpost: good ideas! Yep he's going to need to be GOOD friends with his neighbors.
Jay D.
they say my name is Jay



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PostPosted: Tue Jun 15, 2021 7:33 am
If I remember, if you're painting production, styrene models, lacquer does attack the plastic. Resins, die cast, no problem. You do have to use some sort of sealer first, let it dry well, then put your lacquer on it. I would use what the guys recommended, as 4 to 1 urethane primer. Even a sealer, which might even be better, as it is thinner to begin with. The hi-build stuff you would have to reduce down enough to go through the airbrush.
Last time I did models was for my buddy Vic (who owns the Kopper Kart), he made a batch of 50 of Barris' Aztec in resin and I mixed a candy color and painted them all. I think I used House of Kolor Epoxy primer, thinned down a bit, to seal them. Then all HOK paints. Urethanes.
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PostPosted: Tue Jun 15, 2021 11:32 am
Thanks for all the replies, greatly appreciated to be able to draw on your experience.

we have to be careful here you guys talk different than we do


Yes this is a jungle because there are so many ways to describe these things, and the chemistry matters. But your advice makes sense, now I have some points to guide me when I talk to tha auto paint shop

I forgot to mention what I already have:

Colormatic Plastic Primer/Adhesion Promoter
A spray booth that is vented out onto my balcony where I also spray sometimes.
Facemask that filters solvents
Compressor AS186 3 liter tank, 47 dB
and I am using enamels, 2k clear, lacquers and water based acrylics.

I don't really think my neighbours can hear me working : ) I have my compressor on a big slab of concrete with rubber dampers underneath.

I am also building my spraybooth, right now it is just a kitchen extractor hood upside down and a bathroom ventilator. But I am building it into a proper lighted spraybooth that can extract 150 CFM. And I always wear my mask when spraying and have the windows open on both sides of the building.

I will do some research with the new suggestions, and get back with my findings



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PostPosted: Wed Jun 16, 2021 6:42 am
as a airbrush artist and model builder there are a number of different guns that you will need depending on the size ( scale ) your working on.
being an artist I must have well over a 100 badger 150 airbrushes the reason why so many is I use one for each color this way I don't need to completely clean one to spray a different color. being I have a airbrush for say red , white, black , blue , light blue dark blue and so on.
I was in harbor fright a few years ago and found they have airbrushes so for 20$ I bought one. it wasn't to bad some now I have about 20 of them.
an airbrush is good for doing some modeling but depending on the scale it maybe a little small. this is also the same for airbrush art work.
being so I also have 6 Sata jet 20B's I like the 20B's because they are a good in between size gun. a little bigger then the airbrush and not as big as a mini gun.
I also have a bunch of mini guns. they work good for larger scale.

when it comes to modeling many models have some fine details that any heavy primers will tend to fill with just a few coats also most primers you will have to sand before you top coat. this too will also start to remove fine details you will want to keep.
because of this I tend not to use a primer I will use a sealer. I use a primer product that can also be mixed as a wet on wet sealer . using a product like this if in a area were I need a little more fill I can 1st mix the seal more as a filler primer then add more reducer to get it as a sealer. being wet on wet I can then go right to my top coats with out needing to sand.
for modeling I use U-pol 2253 primer/sealer the mix for the primer is 4 to 1 for a sealer it's 4/1/1. so if you need a little more of a filler primer you can mix it 4 /1 to 1/2 and it will still spray out of an airbrush. I also use the U-pol clear because it uses the same hardener as the primer so your not having to buy lots of different product.
I see on forums people saying to over reduce products to spray them thru an airbrush. in most cases this is not needed to be done and in fact you shouldn't do it. just causes headaches. if you need to over reduce it's just telling you to step up the needle size of your gun or to get a bigger gun.
in my shop I have the BASF glasurit 55 line base coat system and the BASF limco supreme plus system that can be mixed as a single stage or as base coat. for airbrushing I use the 55 line the limco sucks for airbrushing.

for prepping a plastic model. I build many types of models plastic , metal and wood so depending on what type of substrate your dealing with will determine on what your going to use for prep sanding. on plastic models to not sand off and fine details I use a scuff pad that is equal to about a 220 grit. when it comes to sanding pads the color doesn't determine what grit it is. different manufactures will use difference colors so a red pad may not be the same grit from one manufacturer to another.
most modeling plastic is styrene or polystyrene automotive products will not effect this type of plastic. but some of the repaint cleaners will so after prepping for paint stay away for cleaners other than soap and water. I will use dawn dish soap and water but if your going to use dish soap make sure it has no lanolin in the soap.
it will cause fisheyes.



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PostPosted: Sat Jun 19, 2021 12:13 pm
DKBAuto: Wow - you’ve got a real nice setup : ) Maybe some day I will get in the vicinity of that. I can see the appeal in having an airbrush for each color.
But for right now this is a low budget hobby for me. All the kits and lighting is also expensive. And there are a lot of tools and basic stuff I have had to get also.

I already have a near perfect product. But it too expensive. 40ml for 10 USD
So I am looking to find a comparable product and buy a liter of it and be covered (no pun) for a good long while.

I have been googling like a lunatic for days now, but I just can’t find a non transparent sealer in the EU. Maybe it is called something different over here?

If I understand it correctly, a sealer is what you would use to seal in the primer - (for potential dust/debris? Or to smooth it out?)


I have linked tso some similar product before, but here it is in more detail. This sounds to me, like the perfect product for my use case. But then again - I have no experience : )

https://www.billigbilpleje.dk/images/do ... _70383.pdf

https://www.chamaeleon-produktion.de/epoxy-primer.html

Highlights from the PDF:

High gloss retention by wet-on-wet processing
Excellent flow
Grade of gloss: Satin
Thickness about 25-50 μm

Furthermore I can add Elastifier
https://www.chamaeleon-produktion.de/elastifier.html

Which I have read is important for large styrene models. I have at least one model that needs extensive masking/stencil paint jobs on it, so adhesion and flexibility is important.

Now some questions about terminology:
Wet on wet painting? Does this mean painting several layers, building up a wet coat which allows the paint toi flow and auto level? Or have I misunderstood

Base Coat? Does this mean the pre color layer (like priming and sealing) or is it the actual color of the car? Or model in my case…

2K - I know it means 2 components like primer and hardener and optional thinner. But thinner never counts as a component.
But had understood it as the upside to this, was that it would resist solvents in the subsequent layers? But reading your replies, it seems I have misunderstood…

Non Sanding Primer - Does this mean that it goes on smooth or something else - I read somewhere that this is a special primer that chemically bonds with next layer and that it has a redcoat window of a couple of hours?

Here are some pictures of the primer I am using now. It has satin finish, and I can thin it 1:2 without problems. But it is expensive:

https://imgur.com/a/4PlIy9j

This is just small model btw - just for practice


Really really appreciate all the replies - learning a lot each time I log in here
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