Good day! After being a lurker for so long and learning as much as I can, I think I now need to post a question.

I'm trying to learn masking and painting and I seem to have some difficulty with the former. I painted a (scrapped) part and let it cure for 24-48 hours. Masked it then painted it again. I always seem to get some of the paint bleeding into the masked part.

Can anyone please give me some tips on how to avoid this and how to mask altogether?

Thanks!

What brand and type of masking tape did you use?

I would suggest using a masking fluid. You can find a bottle for around $8 and it does not feather. I stumbled upon a perfect camo job the first time I tried it on armor. Just thin with some water and spray it on or don't thin and hand brush it. If you want tape, I use 3M masking and have had no problems with it bleeding. Remember, several light coats. Hope this helps.

I used a not-so-sticky non-hobby masking tape; I'm considering 3M next.



Hmm... I've heard of masking fluids when I first started in this hobby as a kid (Mask Sol methinks); I'll look into it. Anyway, I'm using spray cans and tried to paint the part in one sweep. Should I try to apply light coats first, let it cure, then apply another coat then? Would that not be time-consuming?

The best tape I have used is from Tamiya but it is not the cheapest option.

I rely on 3M blue painters tape, Tamiya masking tape, and poster putty for most of my masking needs.
If you are covering your model in one pass with a spray can, it's probably too thick and obscuring details. 2 or 3 light coats, just enough to get a consistent finish, is the way to go. Is it time consuming? Sure, but then this whole hobby is! Patience will pay off.
As Mr. Miyagi advised, "Wax on, wax off. Wax on, wax off..."

Tamiya masking tape works very well for me. I airbrush a thin mist over the masked area to sort of seal the edges. I let it dry and then I start to airbrush. I always paint from the masking tape to the area to be painted. I do not point the airbrush toward the edges. When you remove the tape pull it towards the painted area so that whatever paint which might still be a little fresh can fall to the paint and not the covered part.

Always spray thin coats and slowly build up. The paint will tack dry, or dry, in a couple of minutes or so, not time consuming by any means. What spray paint are you using?

I'm currently using Tamiya spray cans but will also be handbrushing some of the parts (@SSGToms: which is why I was thinking of time as a constraint; although admittedly, time and patience are two reasons why this hobby is great.)

I wasn't worried about painting the entire part because I noticed that Tamiya's spray cans seems thin enough to not cause any loss in the details; nonetheless, I will try to paint in lighter coats. And if I handbrush, since I will have the paint thinned, I will definitely be applying several thin coats.

Follow-up question: I read on 3M's website they recommend scoring the masked part after painting and before removing the tape, does this apply to plastic models as well?
http://solutions.3m.com/wps/portal/3M/en_US/Scotch-BlueBrand/Scotch-Blue/Tips-and-Techniques/How-to-Mask/Importance-of-Scoring/

I've also read in someone's blog that he sands the tip of the tape just before lifting the tape off. I imagine that this will scratch the paint job, no matter how high the grit. I have tried it and I ended up with scratches. Or maybe I'm doing it wrong...

I would not recommend scoring tape on plastic models, even if you are really good at touch up.

As far as sanding the edges goes, if you have good control over a small piece of sandpaper, sanding stick, or file and can keep it right at the edge of the tape, then you will be able to sand the skin that is connecting the painted surface to the tape and avoid lifting the paint off of the model's surface when you remove the tape. The downside of this is that fine dust particles can get stuck on the surface if the paint is still tacky.

Another trick you can employ to avoid lifting is to roll the edges of the tape, although this could easily create feathered edges on your paint job.

Bluetack would be a great alternative if you can find some. It is reusable and shouldn't give you the problems that tape can give you.

And just as a side note, when you apply your clear/sealer over the paint job it will smooth the surface between different paint colors. This shouldn't be an issue to begin with, but if you apply any of your paint thickly then this will take care of that problem.

Thanks, JeremyH!

I think I will try the sanding technique as it seems to be the best option (from what you offered). Rolling the edges seems to give a higher chance of damaging the paint job.

Re: bluetack, how do you maintain a straight line? By using a ruler? What about if it's a curved edge that you're masking? I'm assuming though that if the paint dries on the bluetack, it will make it less malleable. Or am I wrong?

Actually I meant roll the edges over before you apply the tape, if that makes sense? Obviously not possible if you've already applied the tape and painted

And yes, bluetack will start becoming less usable depending on how much foreign material (paint) is in it.

Another method I've heard of - but not used - is once you've masked - give the area another coat of the base colour - and this seals any gaps, then spray the next colour !

Hmmm -- the sanding idea seems to complicate things more, just my opinion.

Re: 3M Blue Painters Tape -- I haven't really looked around, so am not sure if its locally available. Have tried various locally available DIY-variety masking tapes, but its a pain when you get one that is so sticky it ruins the paint job. And I've had the bleeding problem as well using such tapes. I'd swear by the Tamiya tape -- yes its pricey, but it does the job well.

For straight lines, best to stick with tape. For curved ones, Blue-Tac is good to work with. It doesn't get less malleable after getting paint over it. It just gets less usable as adhesion gets lesser over several re-uses, but I doubt if its because of the paint that got on it.

Cheers