Author Topic: ModelFlex, what primer?  (Read 2730 times)

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diezmon

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Re: ModelFlex, what primer?
« Reply #15 on: June 08, 2018, 09:34:50 AM »
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this thing here.

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learmoia

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Re: ModelFlex, what primer?
« Reply #16 on: June 08, 2018, 09:58:22 AM »
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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.

That is strange, I usually didn't have these kinds of issues spraying darker colors.  But the last time I painted (which was after an 5 year pause, it was a black NYC loco and I had a hell of a time getting a good coat, issues with the airbrush, bad paint, ect..

If it's BN Green on a grey shell, you may not even need primer.. (Try to shoot the BN Green directly on the spoon and see how it looks.. )

I'd have a bit of caution putting nuts (I assume like bolt nuts) in the paint since they may have residue oil from the machining process..

~Ian

 
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diezmon

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Re: ModelFlex, what primer?
« Reply #17 on: June 08, 2018, 10:38:46 AM »
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If it's BN Green on a grey shell, you may not even need primer.. (Try to shoot the BN Green directly on the spoon and see how it looks.. )

that's actually where i started.  No worky.  it had the same look, like water on oil.

peteski

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Re: ModelFlex, what primer?
« Reply #18 on: June 08, 2018, 03:28:20 PM »
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Sometimes I'll drop a couple little nuts in there to break things up when you shake the bottle.

From my personal experience, using (steel) nuts as agitators in water-based paints is asking for trouble.  When I did that, water started rusting those nuts!  The rusty color mixed with with paint, tinting it brown.  It was white paint turned beige!  It happened over a period of couple of years, but the steel will eventually rust.  You better off using lead shot, or glass beads.  I bought bunch of glass beads from a craft store (IIRC, 4mm diameter), and that is all I now use.  Make sure to get glass beads - plastic ones are too lightweight to be useful.
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MK

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Re: ModelFlex, what primer?
« Reply #19 on: June 09, 2018, 07:12:21 AM »
+1
Or you can get Stainless nuts.  :)

peteski

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Re: ModelFlex, what primer?
« Reply #20 on: June 09, 2018, 12:58:59 PM »
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Or you can get Stainless nuts.  :)

Well, there are few different SS alloys and in my experience even some stainless steel can rust.  I have stainless steel caliper and a ruler and both have brown rust spots.  Glass beads are safer, and larger glass balls are also used in rattle cans as agitators (at least the dozen or so cans I have opened up after they are empty and depressurized).
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daniel_leavitt2000

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Re: ModelFlex, what primer?
« Reply #21 on: June 10, 2018, 05:47:42 PM »
+1
I had this same exact issue painting some CR Executive Es. I like Modelflex, and use it as my primary paint. But it can have issues. The wood is porous enough to sop up the carrier and leave the pigment. That's why it has better coverage. I would go with higher pressure, not lower. Shoot from farther away than usual and this will dry out the paint in the air a bit on it's way to the surface.
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diezmon

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Re: ModelFlex, what primer?
« Reply #22 on: June 11, 2018, 10:58:21 AM »
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well, the black went on much easier than the green.  But, there's still that speckled look to it.   I tried lower PSI, around 18.. but man, it went on so light i could barely see it. 

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peteski

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Re: ModelFlex, what primer?
« Reply #23 on: June 11, 2018, 04:33:36 PM »
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That looks very grainy/pebbly.  How about maybe increasing the paint flow (opening the needle more) with lower air pressure?
I'm glad that I'm still able to use AccuPaint/Tru-Color/Floquil/Testors (organic-solvent) paints.  Those seem to be much easier to apply smoothly.
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diezmon

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Re: ModelFlex, what primer?
« Reply #24 on: June 11, 2018, 04:56:29 PM »
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That looks very grainy/pebbly.  How about maybe increasing the paint flow (opening the needle more) with lower air pressure?
I'm glad that I'm still able to use AccuPaint/Tru-Color/Floquil/Testors (organic-solvent) paints.  Those seem to be much easier to apply smoothly.

it's as increased as it'll go.  I'm using a medium tip.  Any lower on the PSI and it'll be invisible.   

I may just go back to the stinky stuff.. sheesh.

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Re: ModelFlex, what primer?
« Reply #25 on: June 11, 2018, 06:56:19 PM »
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it's as increased as it'll go.  I'm using a medium tip.  Any lower on the PSI and it'll be invisible.   

I may just go back to the stinky stuff.. sheesh.

Hmm, so the needle is wide open?  Could it be that the airbrush is clogged and needs a thorough cleaning?  If you spray plain water using the same pressure and needle opening, does it spray out freely (and at fairly high volume)?

I use a Badger 200 with "illustrator" (medium) tip and if I sprayed water at 12psi with the tip wide open, it would come out as a fairly heavy spray.
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diezmon

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Re: ModelFlex, what primer?
« Reply #26 on: June 12, 2018, 09:19:48 AM »
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Hmm, so the needle is wide open?  Could it be that the airbrush is clogged and needs a thorough cleaning?  If you spray plain water using the same pressure and needle opening, does it spray out freely (and at fairly high volume)?

I use a Badger 200 with "illustrator" (medium) tip and if I sprayed water at 12psi with the tip wide open, it would come out as a fairly heavy spray.

It's clear. It sprays water perfectly.  I clean it thoroughly after every use.

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Re: ModelFlex, what primer?
« Reply #27 on: June 12, 2018, 03:14:51 PM »
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It's clear. It sprays water perfectly.  I clean it thoroughly after every use.

It can spray out clear, sure. But I'm wondering if the paint passages/nozzle might have a dried up paint build-up inside, restricting the flow a bit (like clogged human arteries).  Maybe water, not being very viscous will spray out fine, but slightly thicker paint might not flow as freely?  Just a speculation.  When was the last time you have fully disassemble, examine, and cleaned your airbrush.  Again, just a speculation on my part.
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diezmon

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Re: ModelFlex, what primer?
« Reply #28 on: June 12, 2018, 06:12:51 PM »
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It can spray out clear, sure. But I'm wondering if the paint passages/nozzle might have a dried up paint build-up inside, restricting the flow a bit (like clogged human arteries).  Maybe water, not being very viscous will spray out fine, but slightly thicker paint might not flow as freely?  Just a speculation.  When was the last time you have fully disassemble, examine, and cleaned your airbrush.  Again, just a speculation on my part.

I do that every time I'm done painting.. it's spotless.   I used to paint with PollyScale, and no issues like this.  I really don't' know what the dealio is.

Big Train

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Re: ModelFlex, what primer?
« Reply #29 on: June 17, 2018, 12:35:40 PM »
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It doesn't appear to be primer/topcoat mismatch.

Was the primer contaminated with an oil product? What the model handled excessively with oily fingers between painting? Was a paint compatible thinner as recommended by the manufacturer used? Could excess moisture in the air line created during painting cause this paint splatter? Do you have a water trap inline somewhere? It also appears that the air pressure might be too high. I usually spray acrylics at anywhere from 12 to 20 psi.

Try misting light coats rather than applying the paint in one heavy coat. I know it takes longer but patience is a virtue here.

A sandpaper finish is either paint not thinned enough and is dry hitting the surface or too much air pressure. Try using more airbrush thinner (which usually will contain a flow aid to extend drying time to allow paint to level out before drying). Or add Flow Aid directly to your paint. Of course, you know not to returned altered paint (thinned or otherwise back into the paint bottle). Or reduce air pressure. Paint needs to be slightly wet looking when hitting the surface.

If the paint is too thin, I leave the cap off for a day or two to allow the solvent to flash off and that usually increases the viscosity to correct that problem.

From my compressor, with a water trap, the air line goes into a home-built "Second Stage" contraption with another water trap, another pressure reduction valve and finally a pressure gauge (rated 0 to 30 PSI) then to the air brush, usually a Badger 150 or 105 Patriot.

The "Second Stage" contraption really has been the key for me achieving consistent results as I can fail the pressure really low.

As far as primers are concerned, I tried everything before using Badger's Stynylrez (weird name, I know) but it works. Easily the best acrylic primer I've every used through an airbrush. That is my go-to primer now. I usually let it cure 24 to 48 hours, depending an environmental conditions and cures to a smooth opaque finish that is tough. I've had no issues with poor adhesion which seems to plague most acrylic primers. I spray this, neat (undiluted or straight) right from the bottle which now has an nozzle that allows filling the colour cup drop at a time. Prior to applying primer, I wipe the model down with either Tamiya X-20A Thinner or Isopropyl Alcohol.

Of course, your mileage will vary as these parameters work for my conditions. The key with airbrushing is to be flexible with all these parameters and adjust as required.

Once you master some of the variables, airbrushing is relaxing and rewarding I find. Gives you a real sense of accomplishment the you can lay down a good coat of paint.

Hope this helps