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Help with preparing model for paint


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First off, I want to say that I’m a bit new to painting and gluing models. Everything is coming along well except for one part: paint adhesion on one small part of my fa-18e Super Hornet. Paint keeps sliding off of the surface when painting. 
 

I know that you should prime a surface prior to painting, although I have read people have painted their models successfully without it by just washing their plastic model parts with warm water and mild dish detergent first. I have avoiding priming due to the fact that I’m trying to avoid any fumes or VOC’s due to animals in the home with delicate lungs. So I would rather avoid priming or clear coating. I use all non toxic, no fume acrylic paints for this very reason. Again, no problems until this tiny little piece came up. 

 

Can I somehow remove the shine so my paint can adhere better without priming? Like sanding with a particular grit sanding film, for instance. It’s just this one little piece giving me this trouble. 

 

I know many here would probably find a lot of issues with my process of not using primer or clear coats. I’m open to learning more about them if need be. I apologize if that opens this thread up to additional questions due to this. 
 

Thank you in advance. 

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Yes, you certainly can give a light sanding with a fine grit sandpaper to knock off the shine.  Alternately, you could try using a water based primer that does not smell but adheres wonderfully, such as the Badger Stynlrez (or the MIG One-Shot which, I understand, is a relabeled version of the Badger product).  

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1 hour ago, Curt B said:

Yes, you certainly can give a light sanding with a fine grit sandpaper to knock off the shine.  Alternately, you could try using a water based primer that does not smell but adheres wonderfully, such as the Badger Stynlrez (or the MIG One-Shot which, I understand, is a relabeled version of the Badger product).  


Sorry, I have a couple questions about both methods.

 

1) If I use the sanding method, what would you recommend in terms of grit to remove the shine? I’m also wondering if sanding film would be better suited if the spot I’m trying to reach is in a very hard to reach area that would require something very flexible to get in there. 
 

2) My model has both gloss and flat paint schemes on it. It has a range of color from everything from black to white in colors. My paints of choice are Testors and Model Masters acrylics. Is there any particular one color or texture type of primer out of what you mentioned that will worth with all those different colors and flat and gloss paint? I’d like to avoid purchasing multiple primers on my next model if possible if/when I decide to go that route. Btw, it may be important for me to mention that I’ve been painting exclusively with paintbrushes. I’m not comfortable nor do I have the equipment to airbrush. 
 

Thank you for your time. 

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What is the part, what paint are you using, and how are you trying to apply it?

 

I wonder if you are trying to apply too thick a coat of gloss paint? Gloss white paint is well-known to behave like this. You can get a single coat to cover.

 

And agree, you can get some acrylic primers. 

 

The grit should be quite fine, depending on the part, anything from a low of 600 to 3600 and even higher. You should look at a pack of sanding pads, like these or those. They usually start around 1500 and go up to 12000. Also, manicuring buffing sticks should be in your toolbox.

 

HTH

-- 

dnl

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40 minutes ago, dnl42 said:

What is the part, what paint are you using, and how are you trying to apply it?

 

I wonder if you are trying to apply too thick a coat of gloss paint? Gloss white paint is well-known to behave like this. You can get a single coat to cover.

 

And agree, you can get some acrylic primers. 

 

The grit should be quite fine, depending on the part, anything from a low of 600 to 3600 and even higher. You should look at a pack of sanding pads, like these or those. They usually start around 1500 and go up to 12000. Also, manicuring buffing sticks should be in your toolbox.

 

HTH

-- 

dnl

 

I agree with everything this gentleman wrote.  Sanding pads would likely work to get at the harder to reach spots on your model.  The Stynylrez or One-Shot is fine for either gloss or flat paint going over it.  The One-Shot primer comes in a variety of colors, more than the Stynlrez.  And the color of the primer can make something of a difference, depending upon the paint color you're using, and that is largely dependent upon how thick the paint layer is.  Multiple very thin coats is usually preferable to fewer heavy coats, even for brush painting, though gloss is a bit more of a challenge, for me anyway, when brush painting.  Testors Model Master paints would not be my first choice for brush painting; that may be part of your problem right there.  Humbrol enamel (though really stinky) is very brush compatible, as are Lifecolor paints (Lifecolor can be thinned with water).  I'd strongly consider a different paint if you are committed to brush painting.

Edited by Curt B
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1 hour ago, dnl42 said:

What is the part, what paint are you using, and how are you trying to apply it?


I am trying to paint a Revell intake duct (top & bottom) with Model Master Flat White Acrylic. I’m unfortunately unable to post a photo as it is to large for this post. 

 

I unfortunately painted it to the best of my ability. It took four coats to cover it the best I could. It normally only takes me one to two thin coats. I know that there is probably no way of fixing the issue now. This is more of a learning experience on what to do with my other intake and future models.

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56 minutes ago, Curt B said:

Testors Model Master paints would not be my first choice for brush painting; that may be part of your problem right there.  Humbrol enamel (though really stinky) is very brush compatible, as are Lifecolor paints (Lifecolor can be thinned with water).  I'd strongly consider a different paint if you are committed to brush painting.


I would absolutely agree with you on the paint choices. The problem is the fumes of enamels and thinners aren’t much of an option for me with my birds’ delicate lungs. So I’m working with what I’m limited to. Do you know of any other acrylics that are better than Testors Model Masters Acrylics that won’t need thinner? I would gladly try those next if they’re better than what I’m using.

 

sorry for making it so complicated with avoiding stuff that gives off fumes. I know it would be much simpler without having to avoid such things. 

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Maybe you can fix it. I've just stripped a complete model because I was unhappy with the base coat. I had primed with Mr Surfacer and then airbrushed Alclad. I was able to strip the paint using Mr Color Thinner applied with cotton pads and swabs. 

 

To be sure, I have models with errors large and small. The AT-6 in my current signature has 2 horribly wrinkled wing stripes. The key is to learn. In those cases, it was what not to do, but hey, that's learning. :whistle:

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Regarding stripping your paint, I don't know what would be the best method to strip Model Master paint from a model.  I have experience (just recently, in fact) of removing Tamiya paint, applied years ago, from a model.  If you use Windex, with ammonia, Tamiya paint comes off like Windex was made just for the purpose.  It's amazing.  I don't know if there is an equivalent solvent for dried Model Master paints.  

 

Regarding suggested paints, for an acrylic that gets good reviews for hand brushing, there is Vallejo.  I have a lot of this paint myself, and I agree that it hand brushes well.  And they have a lot of colors.

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Something I'll often do before painting model parts of suitable sizes, or entire models, is give it/them a gentle scrub with an old soft toothbrush and one of the 'soft scrub' style kitchen cleansers. That serves a dual purpose of removing my skin oils after handling the parts or model and it slightly dulls the surface of the plastic, kind of like sanding with that really fine grit almost paper-smooth sandpaper.

 

Though that might be something not readily doable to already built intake ducting.

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4 hours ago, southwestforests said:

Something I'll often do before painting model parts of suitable sizes, or entire models, is give it/them a gentle scrub with an old soft toothbrush and one of the 'soft scrub' style kitchen cleansers. That serves a dual purpose of removing my skin oils after handling the parts or model and it slightly dulls the surface of the plastic, kind of like sanding with that really fine grit almost paper-smooth sandpaper.

@southwestforests, That is one thing I did with the all the pieces of the model before painting. Unfortunately, these few pieces I have and am having trouble with is very glossy still. Would you recommend hitting such completely bare plastic yourself with 600 grit sanders or no for such a problem? Would you go for a higher grit? Looking for that finish you’re talking about. 
 

TBH, I have Squadron sanding sticks that aren’t quite doing the job. Mostly due to the fact that it’s in hard to reach areas and/or areas not completely flat. Additionally, it doesn’t state grit, so having trouble gauging on what to start with when it comes to actual sanding material referencing grit.


Also, some of the material is thin, so I’m also wondering if primer would be a better option as opposed to just relying on sanding, but from a previous post, it seems that acrylic non toxic primers, like One Shot, doesn’t offer good paint adhesion to other non toxic acrylics like Testors Model Master. If I do get a primer, it MUST be non toxic. So I’m in a bit of a pickle here. 
 

i should mention that my model is a Revell plastic model. Not sure what type of plastic it is made of. 

Edited by Historybuff
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5 hours ago, Historybuff said:

Unfortunately, these few pieces I have and am having trouble with is very glossy still. Would you recommend hitting such completely bare plastic yourself with 600 grit sanders or no for such a problem? Would you go for a higher grit?

 

5 hours ago, Historybuff said:

i should mention that my model is a Revell plastic model. Not sure what type of plastic it is made of. 

 

Styrene, polystyrene, is the most common plastic model plastic. Some kits from some manufacturers are molded in ABS, Acrylonitrile Butadiene Styrene, instead of polystyrene. ABS requires different plastic cement but all the various paints I have used, Testors classic 1/4 floz enamels, Polly Scale acrylics, Tamiya Acrylics, Acryl, several brands of miniatures game paints, have worked well on both.

 

The paint non-adhesion to plastic situation is one I've not encountered. I'd have to try some things myself and see what happens.

But I would have more options for things to try since chemical vapors are less of an issue in my birdless house.
Their health and lives have to be protected, that comes first.

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Thank you for trying to help with my issue. I’m gonna experiment a bit with my other intake duct and see if I can find a solution. I’m going to try sanding first. Kit is being shipped to me due to the virus going around though, so it’ll be a bit before I know what happens experimenting with it. Hopefully that works. I may get some non toxic primer if that doesn’t work too well or good enough for paint adhesion. I can let you all know if I find a solution based on your guys’ help. 

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If you can clean the plastic first with isopropyl alcohol (I use 100% IPA), that will help a lot with paint adhesion, but it might be a little hard to find at the moment. Using water-based acrylics is always going to cause you more problems in this area that using, say, a lacquer acrylic (like Mr Color, MRP, etc.) or a hybrid (like Tamiya or Mr Hobby), but I understand the limitations you have that restrict you to the water-based stuff.

 

Jon

Edited by jonbryon
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  • 2 weeks later...

The results are in. I got some good wet/dry sanding paper containing 320, 400, 600, 800, 1,200 and some higher grit together in a pack. I’m still planning on getting the recommended materials posted above by others, btw.

 

I wouldn’t say that it has solved all the problems. It has, however, given me a workable surface to paint on with only needing a few light coats. It was taking as many as FIVE coats to fully paint the area. 
 

a bit of a side note: white acrylic seems to be much harder adhering than something like gray acrylic paint. Not sure if this is common or if I just got a bad batch of white paint. Nevertheless, white WILL adhere. It just takes one or two more coats. 

Edited by Historybuff
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Gloss white is a Hard color to apply. The key is to apply light coats for coverage and then apply a final wet gloss coat. Same process for yellow. Well, you should always paint this way for all colors, but it's critical for white and yellow.

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On 4/21/2020 at 9:35 PM, dnl42 said:

Gloss white is a Hard color to apply. The key is to apply light coats for coverage and then apply a final wet gloss coat.

I’ve definitely learned this lesson. I’ve gotten better at applying thinner coats with paints as time has progressed. Although I will say that I have gotten away wit a few heavy coats earlier on with other colors. White just definitely seems like to leaves you with really no room for error. Otherwise, it looks horrible and drives you nuts. I definitely appreciate the advice. 

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@Napalmakita, I haven’t been able to come across many other types of paints other than, Testors, MM and some Tamiya and Vallejo acrylics at my local hobby stores. I’m planning on looking some more at other places and online. I’ll keep my eye out for Ammo paints. I’ll definitely keep my eyes peeled for that Ammo acrylic primer as well. It may just take some trial and error to figure out what works best for me, so Ammo primer will definitely be a primer I keep in mind. Thank you for your input. 

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