ModelFlex, what primer?

[diezmon]

So, I tried airbrushing for the first time in about 15 years tonight. An N scale stripped engine. Disaster.   I used modelFlex, right from the bottle, about 30psi.  Instead of covering smooth, it went on a bit splattery, for lack of a better word, not solid.  so I moved a bit closer but that caused the extreme orange peel look.   I'm thinking the plastic needs primer to give it some 'tooth'?  I've always used acrylics and had never needed to prime in the past, so what's the dealio here?  I used to be good at this sh!t

I recall a thread where someone was talking about primers, but i can't seem to find it.  I did read that, generally, some use spray bombs for primer, but I'm afraid it'll hid the details on an N scale model.

So, what do you prime with, hmmm?   

And no, the modelflex isn't 15 years old.   

[peteski]

It seems to me that you have more problems than just primer.  I still use the stinky paints, so I won't be much help.  With my stinky paints I spray at 15-20 psi.
The thread you are looking for is just 4 down from yours (at least now). 
https://www.therailwire.net/forum/index.php?topic=44767.0
 

[learmoia]

I think Model Flex makes a primer that works fairly well..

The dark model flex colors are really nice, but the lighter colors are tough to airbrush.. I read that you should thin the paint to the consistency of milk which MF paints seem to be, but keep in mind that they like to gel up at the bottom of the bottle, and you need to stir/shake all that out, or filter it out before you start.
 
Also MF pint has a tendency to dry as its hitting the model which leads to a sandpaper finish.. They make an extender that helps reduce that. 

For Model flex 20-30 PSI should be fine.. Don't go over 30..

Edit.. 2 situations where I have gotten the 'spitting' effect..
1:the feed tube is partially clogged with a hunk of gel at the bottom of the bottle.

2: damaged needle/tip that causes paint to build up and dry as it hits the air stream.

With some practice I've had good luck with it overall..

~Ian

[diezmon]

Also MF pint has a tendency to dry as its hitting the model which leads to a sandpaper finish.. They make an extender that helps reduce that. 


~Ian

ah, you described it perfectly, "sandpaper finish" 

[learmoia]

ah, you described it perfectly, "sandpaper finish"

Well, I have also had a 'splattery' finish too.. If the airbrush is passing through small chunks if 'paint gunk' it will have a splatter finish.. (like a faint textured wall finish in your house)..

~Ian

[diezmon]

So, gave it another shot the other night.   Sprayed at 20psi,  right out of the bottle.   The body has been primed with a spray bomb.

Still looks like hell.  Maybe i'll try even less psi, and ultra light coats.

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[wazzou]

My first and biggest suggestion is to buy yourself a box of White Plastic Spoons. 
I always, prime them the way I plan to prime my model and test spray on them before spraying a model. 
This allows you the opportunity to tune in your distance, air pressure and paint mix.

[diezmon]

My first and biggest suggestion is to buy yourself a box of White Plastic Spoons. 
I always, prime them the way I plan to prime my model and test spray on them before spraying a model. 
This allows you the opportunity to tune in your distance, air pressure and paint mix.

ha, good idea.

[learmoia]

Plastic spoons is a good idea...

I don't think less PSI is going to fix that..
Based on the looks of it.. Paint may be too thin (which you can't do anything about that) But too much volume of paint to start. Combined with the acrylic paint over enamel or lacquer primer effect.... Imagine what happens when you spray water on oil..

Try to:
Strip.. And Re-prime with Model Flex Primer 16-12 Primer Gray
- OR if Hobby Lobby is your local hobby shop
I've had decent luck with TESTORS 4680 Model Master "Acryl" Gray Primer. Make sure to get the one that says Model Master "Acryl" primer..
Also I'd suggest that you invest in the Testors Accrylic thinner 50496A - 4 oz. Acrylic Airbrush Thinner.

I believe you can thin acrylic paint with distilled water, but I've had better luck with the accrylic thinner, which retains the additives that make accrylic paint what it is.

When you paint.. start with a very fine mist.. (almost no color).. and lightly spray everything.. with the primer..
Then go back and recoat with a slightly thicker coverage.

Then do the same with the green.. real fine mist to start.. then go back over it with a slightly thicker coat.

~Ian

[peteski]

Yeah, the paint looks like it is beading up on the model (like water on oily surface). The paint might be too thin. I wonder if it is mixed/stirred thoroughly enough? Maybe the pigment settled down in the bottle and will take some coaxing to get it back into suspension.

[diezmon]

Yeah, the paint looks like it is beading up on the model (like water on oily surface). The paint might be too thin. I wonder if it is mixed/stirred thoroughly enough? Maybe the pigment settled down in the bottle and will take some coaxing to get it back into suspension.

I stirred and mixed the heck out of it. I think next is trying the different primer.  Why haven’t I heard of others having this kind of bs?  Sheesh

[nickelplate759]

I stirred and mixed the heck out of it. I think next is trying the different primer.  Why haven’t I heard of others having this kind of bs?  Sheesh

If it helps, I've had similar problems, and uneven results in fixing them. Also, the stuff clogs my external-mix air-brush in a hurry, so I solved my problem by switching to Tru-Color paint - except that I really like the finish that the Model-Flex gives when it works right, and they have some very good colors.

[Doug G.]

Notice how relatively nicely it covered the wooden (or whatever it is) support.

Doug

[learmoia]

Notice how relatively nicely it covered the wooden (or whatever it is) support.

Doug

Yeah I noticed that too, which leads me to believe the paint itself is likely OK, but more of an issue with a reaction between the paint and primer. 

Another pointer.. when you shake / stir the paint, stick a toothpick down and stir the bottom and see if you can pull up (or feel) any lumps of pigment.

Oh yeah, don't get let down by what your going through.. we've all been through it..   BTW what's the model (SD10+ I assume) or a 9 rebuild).. what color Green?

[diezmon]

Yeah I noticed that too, which leads me to believe the paint itself is likely OK, but more of an issue with a reaction between the paint and primer. 

Another pointer.. when you shake / stir the paint, stick a toothpick down and stir the bottom and see if you can pull up (or feel) any lumps of pigment.

Oh yeah, don't get let down by what your going through.. we've all been through it..   BTW what's the model (SD10+ I assume) or a 9 rebuild).. what color Green?

Yeah, last time I painted was around 10 or more years ago.  I remember it being easy!   I did stir it and pretty much did exactly what you said, but using a wood coffee stir stick.  Sometimes I'll drop a couple little nuts in there to break things up when you shake the bottle.

The unit is a BN SD9.  It's interesting to me because of the flat cab roof.  I saw it in my 1971 BN annual.