Paint peeling

Unwary, Sorry to hear that. My guess is that you're painting with acrylics. It can really ruin your day when that happens. How about some of these: Maybe you didn't let the primer cure before you topcoated it. Maybe you handled that area before you primed it and had a lot of dust on your fingers, or your fingers were extra oily. Maybe you sneezed by it and blew a lot of dust onto it before you primed it. Maybe you put the primer on too thick and it didn't cure properly. Maybe you held the airbrush too far away from the model and it dried too much before it coated the plastic so it didn't have enough moisture to grab the plastic. Or my favorite, maybe you just didn't get all the mold release off when you washed it. I've stopped trusting soap and water to do the job. I use ISO for everything now. Sometimes, no matter how careful I was with soap and water, I'd still get spots where the paint just nearly slid off the plastic, no grab at all. I doubt seriously that it was anything you did wrong. You just got a model with a lot of mold release on it and the soap and water didn't get it all off. Barrett

mississippivol

Acrylic or enamel Model Master?

 

I would always prime with enamel first.  I use MM enamel  as a primer then Tamiya acrylic.  The paint has never come up from masking.  Always let dry for a day or more as well. Patience has its rewards where paint is concerned.

I would also recommend Tamiya masking tape.  It's not that expensive if you buy just the rolls and not the dispenser.

I would not risk using even 3M blue masking tape.  Not on an expensive model.

BarrettDuke

Unwary, Sorry to hear that. My guess is that you're painting with acrylics. It can really ruin your day when that happens. How about some of these: Maybe you didn't let the primer cure before you topcoated it. Maybe you handled that area before you primed it and had a lot of dust on your fingers, or your fingers were extra oily. Maybe you sneezed by it and blew a lot of dust onto it before you primed it. Maybe you put the primer on too thick and it didn't cure properly. Maybe you held the airbrush too far away from the model and it dried too much before it coated the plastic so it didn't have enough moisture to grab the plastic. Or my favorite, maybe you just didn't get all the mold release off when you washed it. I've stopped trusting soap and water to do the job. I use ISO for everything now. Sometimes, no matter how careful I was with soap and water, I'd still get spots where the paint just nearly slid off the plastic, no grab at all. I doubt seriously that it was anything you did wrong. You just got a model with a lot of mold release on it and the soap and water didn't get it all off. Barrett

 

It could be how I'm washing the plastic. I use acrylic, so there's always some touch up where masking pulled up some paint. But nothing this bad. You just use off the shelf isopropyl alcohol to clean off the mold release? I guess I'll just use the tape to remove as much paint as possible, clean and repaint. Ugh, it was supposed to be a simple fun build!

I always use an actual primer, so many hobby paints called a primer are simply paint. My best luck has been with Badger's "Stynylrez," or Tamiya spray can primer decanted and airbrushed. Haven't had a paint lifting problem in a very long time.

I hope Don Stauffer will stop by, he has lot's of info on commercial spray can primers, that might be something you could find helpful. A faultlessly clean surface under the primer is actually essential. I leave the parts on the sprue, then submerge them all in a wide pan filled with warm water and soap. With a large soft brush I scrub the sprues to a good lather, then a triple rinse and dry. ISO is my final step before spraying assembled models, I always use a clean wiping towel, I use Kim-Wipes and change frequently.

I know it may considered overkill, but consistent good results are important to me.

Patrick 

Unwary, I use 90% ISO. The standard stuff at the store is 70%. My guess is that it will work just as well, but if you can find 90%, then get that. Try a drug store instead of a grocery store. The added benefit with the ISO is that you have less worries about the model drying. When you use soap and water, you have to wait a long time to make sure the water is all dried up. ISO helps with the evaporation issue. In addition, you don't have to worry about making sure you got all the soap off, which can be another reason your primer didn't stick. As far as removing the paint to start over, you can use Windex to remove the acrylic paint. It dissolves that stuff like nothing else. As for primers, I agree with those who are saying to use a non-water based primer. The Tamiya spray can primer is great. I also really like Mr. Hobby primer. It's very fine, goes on great, and doesn't cover up detail. Spray it on in a very thin layer, just enough to cover the plastic, and it will give you a really strong bonding surface for your acrylic. Best of luck to you. Any day you're working on models is a good day! Barrett

I've only washed one model before assembly in the recent past, my Revell Snowberry. Guess what, tape pulled up the paint.

Don't do it unless it's a sad old Eastern Express kit from eBay.

Use real primer. I only use Tamiya White in the rattle can, except recently I used Rustoleum, the red stuff because I though hey what the heck I'll salt technique back to the primer for a rusty look. Failed at that.

Regular masking tape is not allowed on the bench. There's a reason painters don't use it.

3M blue comes in a range of tacks, and they are identified by the color of the cardboard core. I've had good results with Orange, but blue and green are agressive.

They are designed around how long you leave them on the surface.

Take the tape off just as quickly as possible once the paint sets.

Drying time. Enamel dries from the inside out. Give it a week minimum.

Acrylic skins and dries from the outside in. Give it a week.

My best results masking is to do the following. Use Tamiya yellow tape. De-tack it as you noted. Mask with pieces at most 1/4" long. Work your way around the area carefully and lightly rub it down with your finger nail. Use a toothpick to get it down into details. If possible, run a thin coat of the color to be overpainted on the mask edge, to seal it and make bleeds not visible.

Come in from behind with blue tape that really is only adhered to the Tamiya tape, not the model.

Regular masking tape are never a good idea. Blue painter tape is ok but I prefer using yellow Frog painter tape instead. They have the same tackiness as Tamiya tape. 

patrick206

I always use an actual primer, so many hobby paints called a primer are simply paint. My best luck has been with Badger's "Stynylrez," or Tamiya spray can primer decanted and airbrushed. Haven't had a paint lifting problem in a very long time.

I hope Don Stauffer will stop by, he has lot's of info on commercial spray can primers, that might be something you could find helpful. A faultlessly clean surface under the primer is actually essential. I leave the parts on the sprue, then submerge them all in a wide pan filled with warm water and soap. With a large soft brush I scrub the sprues to a good lather, then a triple rinse and dry. ISO is my final step before spraying assembled models, I always use a clean wiping towel, I use Kim-Wipes and change frequently.

I know it may considered overkill, but consistent good results are important to me.

Patrick 

 

My go-to primer is Rustoleum primer. Why? Not only it’s wet and dry sandable, sprays really nice and smooth straight out of the rattle can (I spray in 2 light coats), and it’s economical for me. 

To "me too" Patrick and Bill, I'm not sure Testors even makes an acrylic primer, mean an acrylic primer that is acrylic. They have a grey acrylic color that, as Patrick mentioned, is cleverly named "Grey Primer".

And you mention that paint pull up is common for you, just not this much. No, that cannot be acceptable. I've been painting with acrylics since 2013 and haven't had a paint pull up since my first model, and that was Testors "Grey Primer" with a testors acrylic over it and to "me too" Sheep, blue painters tape.

As many mentioned above, use a real primer. It doesn't have to be oil-based, Badger Stynlyrez works great. I've yet to try model master over the top but I'll bet it'd be fine.

Thanks for the help!

- What kind of Rustoleum primer do you use, do you recommend sandable? Any brands/types to avoid, any that will eat plastic?

- After decanting a primer, do you need to thin it for airbrushing? 

- Sometimes I'll use acetone to smooth out the Tamiya putty (I'm switching to perfect putty when this tube runs out!) and I've noticed that acetone will remove paint quite easily. Should I avoid acetone as a paint remover, is it too aggressive? I haven't noticed any ill effects on the small areas. 

I used masking tape to remove 90% of the oive drab, pulled it right up. I noticed that the tape doesn't pull up the areas with primer alone. I wonder if the olive drab paint softened the primer? Maybe I didn't give the olive drab enough time to cure, in addition to the inadequate surface prep.

If the primer doesn't peel off where it wasn't topcoated, that suggests that the primer didn't have enough time to dry/cure before you topcoated it. The primer might stilll have been gassing out or drying when you painted over it. With a layer of acrylic on top of it, perhaps the only place the remaining moisture and gasses in the primer had to go was between the primer and the plastic of the model. As someone said, acrylic dries from the outside in, so it needs time to dry/cure all the way through before topcoating it. Barrett

May be overkill on my part, but after cleaning the sprues prior to the build, I'll use a gray scotchbrite pad to put some tooth into the plastic for paint to bite to.  Also use it as a final scuff if I don't have any issues such as runs or dirt to deal with.  Then a wash with wax and grease remover just before paint.

GM's hint on sealing the edge of the tape with the color under it is good, can do the same thing with clear as well.

The scotchbrite pads and wax/grease remover can be had at any auto paint supply store. A couple of pads and a quart of wax/grease will last a long time, and they might have some finer "grit" pads if you find the gray is too agressive for you.

Good luck on the repairs, been there, done that and have a few t-shirts in the drawer from the same problems.

UnwaryPaladin

Thanks for the help!

- What kind of Rustoleum primer do you use, do you recommend sandable? Any brands/types to avoid, any that will eat plastic?

- After decanting a primer, do you need to thin it for airbrushing? 

- Sometimes I'll use acetone to smooth out the Tamiya putty (I'm switching to perfect putty when this tube runs out!) and I've noticed that acetone will remove paint quite easily. Should I avoid acetone as a paint remover, is it too aggressive? I haven't noticed any ill effects on the small areas. 

 

 

Rustoleum Grey Primer. It will say wet and dry sandable on the can. I don’t decant my primer - I spray straight out of the rattle can.

I will say this - avoid Krylon paint and primer like the plague. They’re garbage. Ask me how I know....

BlackSheepTwoOneFour

 

 

patrick206

I always use an actual primer, so many hobby paints called a primer are simply paint. My best luck has been with Badger's "Stynylrez," or Tamiya spray can primer decanted and airbrushed. Haven't had a paint lifting problem in a very long time.

I hope Don Stauffer will stop by, he has lot's of info on commercial spray can primers, that might be something you could find helpful. A faultlessly clean surface under the primer is actually essential. I leave the parts on the sprue, then submerge them all in a wide pan filled with warm water and soap. With a large soft brush I scrub the sprues to a good lather, then a triple rinse and dry. ISO is my final step before spraying assembled models, I always use a clean wiping towel, I use Kim-Wipes and change frequently.

I know it may considered overkill, but consistent good results are important to me.

Patrick 

 

 

 

 

 

My go-to primer is Rustoleum primer. Why? Not only it’s wet and dry sandable, sprays really nice and smooth straight out of the rattle can (I spray in 2 light coats), and it’s economical for me. 

 

I use Rustoleum primer myself, but they make a few kinds.  The one I am using now is just called "sandable primer."  I almost always use primer, but have occasionally done a model without it.  Priming is not the only issue with paint adhesion- there are a number of issues that create poor adhesion.  If you do wash a model with soap and water, make sure you rinse it thoroughly.  Even a slight soap film is more of an issue to paint adhesion than molding release agents!  With some fast drying paints, too thick a coat can create problems.  Changing brands or types of paints between coats can be an issue. I also find painting over certain metallic colors can be problematic.

Any time you are trying out anything out of the ordinary, test on scrap plastic first. If all else fails, check the phase of the moon!