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  #21  
Old 03-06-2011, 11:01 PM
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Mark II Mark II is offline
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Pulling the tape off can often produce tiny "ruffles" along the masked edge even if it doesn't pull off any of the pant itself. So that's another reason why it is good to remove it while the paint is still somewhat liquid; the paint can still flow a little bit and even out or "settle down" the masked edge after the tape is removed.

I don't know about any black stripe decal; my kit came with the current stick-on decal set, which I decided not to use. When I saw the 1970s Alpha decor I immediately thought of using pinstripe tape for the vertical stripe. What came as a complete surprise to me was the fact that I could, with care, peel it back off without damaging the underlying paint and adjust it to get it straight. I ended up having to do that twice, and yet the pinstriping still clings tenaciously.
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  #22  
Old 03-07-2011, 04:08 PM
BPRescue BPRescue is offline
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I have done a bit of painting, not necessarily rockets, but using many different kinds of paints/finishes. The issue you are having can be caused by so many different things. Incompatibility in paint types, heat, moisture, old paint, bad paint, inferior base coat, no primer, etc. Gloss can present the issue more prominently because the surface you are bonding with grabs less than matte, flat, etc.

Just like anything when you troubleshoot, you can’t go for the most complex explanation first and need to keep it simple. I tend to wonder if you removed your tape at that magic moment where failure was imminent. It is well known that removing tape when it is wet works well. You can also remove it when it is dry as well with good results. In your instance, it may be that you removed it at the perfect time where the paint was starting to set, but did not have a good bond with the surface below. So, in this case removing the tape earlier; or later would have worked.

Something I think I am missing is those who say the remove tape when the paint is wet, however have more than one coat. In that regard, how do you coat it a second time and get the tape matched perfectly to your prior lines? This would be difficult for even the most skilled of modelers.

Yet another issue is that if you put coats on too quickly. If your 1st coat does not have enough time to set, and you hit it a 2nd time, and even a 3rd time, it can be the same exact thing as doing one heavy coat as the layers will bond together and become fragile. The only difference in this example would be that you would not have a run problem. Running is not the only reason you do not want a thick coat. Allowing enough time in between coats to set, will make a stronger and better finish. Anyway, in this instance, where multiple coats are sprayed within minutes of each other can cause a reaction in all coats and weaken them enough to tear apart as you lift the paint off. In this example where multiple coats are sprayed quickly, even if you wait until dry, you will still have a weaker/less durable surface that will easily be dinged/chipped and in some instance separate from the bonding surface, be it primer, another paint, etc.

I read another post where someone talks about using the tape to “cut” the paint. This does work well, and though you don’t have to do it for every application, it is a good habit to get into since it is much easier to lift paint, than to pull it. I have also found that using a good tape helps. Home Depot has Blue tape that I use for just about everything. It releases well and does not cause stress to fragile base coats. I cannot remember what it is called, but you will find two different types of blue tape there. One is thicker and if you look closely, you can tell it has an imperfect outer surface. The best tape I have found is blue as well, but it is thinner and perfectly smooth. Yet another poster on here mentioned the tape being a culprit; then realized he was talking about a cleaner edge. I have found that using this tape not only provides a better edge, with no bleeding, it also allows safer removal than the other stuff. I think being thinner has something to do with it since there is less edge area to grab curing paint. Either way, there is no doubt it creates the cleanest of edges, but also limits failures when removing. I will look for the exact name when I have some time, but again holding them side by side you can tell the difference. I know 3M makes it.

When I paint, I usually put on 3 or 4 VERY thin coats. The first coat may look bad in that it does not show uniform color/cover the primer, however the intent is not to provide” full coverage” on each coat, but instead multiple thin coats that collectively create the uniform coverage you are trying to obtain. With thin coats, it sets faster allowing fast recoat times and does not build up against edges. After the final coat dries a bit, I will remove the tape and never have issues. Keeping in mind, it can be 2 hours or more before I remove the tape, it clearly is not wet. Using this tactic, I get perfect tape line, with a minimal lip.

It can be other issues, such as bad paint, old, moisture, etc. but I would start simple, even run some tests and see what you find. BTW, I mentioned primer as being a possible issue. I should clarify and indicate a lack of primer can cause failure. Paint will react differently if primer is not used even if the paint you are covering has “cured”. This chemical reaction can cause the paint underneath to blister. In that regard, it is always best to prime…

I guess this is like most things; people use the tactic that works for them. Hopefully this supplied enough to help identify a possible issue.
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  #23  
Old 03-07-2011, 07:56 PM
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Remove the tape after the last coat. Each coat's solvents soften the layer that's already there, making it easier to remove tape smoothly.
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  #24  
Old 03-08-2011, 06:20 AM
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When you are masking for a second color, you are almost always preparing to add a darker color over a lighter color. In such situations, one coat is sufficient. In the OP's situation, which is quite typical, he was applying black on top of a base color of white. He would have had to have been using truly inferior paint, or have been applying it to a high relief surface, or both, to have needed to apply more than one coat.

Waiting until the paint is completely dry before removing the tape mask does work, but it almost always leaves a small raised ridge along the mask line. When you are painting small models with some detail, such a phenomenon can be very apparent and unsightly.
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