Repainting bare plastic spot and getting edges

+1 here. I was just about to search this forum for an answer to this exact same issue and saw this post!

I'm am paiting a large white surface so I think that makes it 100% more visible than perhaps a darker colour. 

You need to sand back the edges, and "feather" the edges to a gentle slope, the same way it's done in an auto body/paint shop

Thanks, will try sanding.

It doesn't totally make sense because if you paint two layers back on, shouldn't it be even? Or is it because the original paint is getting two more layers as well?

You're thinking is correct. When painting an area where the paint has lifted, the entire area must be sanded smooth. Otherwise you will just keep making the remaing paint grow thicker, while painting the bare area. It will always continue to do just that.

Sand the area so the edges cannot be felt, it may require a good bit of sanding. Don't sand with just a fingertip bearing down on the edges, use a pad of some sort to distribute the pressure over a wider area, that way you avoid creating an uneven trench. Make the final sanding steps with finer sand paper, so you don't leave scratches.

Patrick

patrick206

You're thinking is correct. When painting an area where the paint has lifted, the entire area must be sanded smooth. Otherwise you will just keep making the remaing paint grow thicker, while painting the bare area. It will always continue to do just that.

Sand the area so the edges cannot be felt, it may require a good bit of sanding. Don't sand with just a fingertip bearing down on the edges, use a pad of some sort to distribute the pressure over a wider area, that way you avoid creating an uneven trench. Make the final sanding steps with finer sand paper, so you don't leave scratches.

Patrick

 

 

Ditto. Go on You Tube and watch an auto painting video and you will see how the area in question is sanded to a feather edge that eliminates the step. This is SOP when doing spot repair painting.

One way if you can mask off just the section or panel the bad point is on, and sand with a small piece of 1000 grit paper.  Then repaint.  The masking before sanding protects nearby finish.  You may see panel "line" but it will be faint, and will just look like a panel.

Thanks! Will get some sandpaper and try again! Really it's not that noticeable but I don't like my mistakes to be passed off as intended part of the model.

starwarsdude

Thanks, I tried with a sanding stick but couldn't make meaningful contact. So I ordered some 800 grit sandpaper that I can cut up. Is 800 a good grit for airbrushed acrylic paint on a plastic model?

 

https://www.amazon.com/M-jump-Touch-Sanding-Polishing-Grits

We all started modeling thinking that paint would work to some degree to smooth over or hide blemishes. No longer true.

Today's paints, applied with an airbrush, can be very thin coats. If anything, a good thin coat of paint will make flaws more apparent. I've learned to think of my paint finish quality as a result of working at a fine finish from the inside out, not the other way around.

GMorrison

 

 

starwarsdude

Thanks, I tried with a sanding stick but couldn't make meaningful contact. So I ordered some 800 grit sandpaper that I can cut up. Is 800 a good grit for airbrushed acrylic paint on a plastic model?

 

 

 

 

It's not really. It could be ok for a flat finish if you use light pressure and don't dig in. Look into investing in a set of Micro Mesh sanding pads. They'll last you a while, and they do a better job.

 

https://www.amazon.com/M-jump-Touch-Sanding-Polishing-Grits

We all started modeling thinking that paint would work to some degree to smooth over or hide blemishes. No longer true.

Today's paints, applied with an airbrush, can be very thin coats. If anything, a good thin coat of paint will make flaws more apparent. I've learned to think of my paint finish quality as a result of working at a fine finish from the inside out, not the other way around.

 

Patrick

The 1000 grit paper does something but I wasn't able to repaint and make the edge invisible. I ended up using thinner to remove a bigger area and am starting from bare plastic on that section. Probably made it worse but hey I tried to make it as good as I could. Bad hobby for perfectionists!

I researched and perhaps Vallejo primer is to blame for pullup so I'll try Badger Stylnrez.

Sad that this model will never have a nice smooth paintjob but it is the Millennium Falcon. Yet another learning opportunity... resulted in learning to sand edges and to try better primer on my next one.

While I've not used Stylnrez primer, Tamiya's Fine Gray primer is the best that's out there for primers as far as I'm concerned. Goes down thin, won't obscure detail, never had paint lift when using it.  Their white primer would be my second choice. It's in a rattle can, but you can decant it and use it in your airbrush if you want. Used it on resin and plastic with no problems.

starwarsdude

The 1000 grit paper does something but I wasn't able to repaint and make the edge invisible. 

I researched and perhaps Vallejo primer is to blame for pullup so I'll try Badger Stylnrez.

 

Some guys love Badger Stylnrez and swear by it bu I second Tamiya primers. They are simply awesome. Mr. Surfacer 1000 and 1200 are also fantastic. I don't like using acrylic primers cause they have a good chance to lift specially MM acryl primer that is simply trash. 

I can't use rattle cans near my place so it's airbrush only. Also don't like fumes. Just using acrylics.

You mentioned above you used Vallejo surface primer. That product is not sandable, so I suspect that is your problem attempting to correct the pull up. IMO, you are never going to get a perfect edge at this point. I used that product once, and had this exact thing happen to me. It has poor adhesion and doesn't sand at all. (unless it's had a month to cure, .....maybe) It's great for figure painters becuase it does a wonderful job of self-levelling and surface detail simply pops.

starwarsdude

I can't use rattle cans near my place so it's airbrush only. Also don't like fumes. Just using acrylics.

In that case, Stynylrez is really your best, if not only choice. (Yes, I know I'm repeating previously given advice).

starwarsdude

Yes exactly... sanding is just ripping off more paint and I still have a step (with a much larger area to repaint)

That's a perfect explanation of what Vallejo Primer does when you try to sand it. Well said!

starwarsdude

I will consider it a education and stop using Vallejo acrylic primer. My next Falcon will have Badger Stynlrez primer.

Atta boy.