Paint lifting w/ tape....need advice

The "light bulb in a vented box" works better. I would add a small fan blowing into an open side of the box.

What I use is a forced air food dehydrator. It has a heating element with a thermostat and a small fan.

I live in northern ILLness—the relative humidity never goes below 50% from April to October, so I know what you mean. I've also lived in coastal Florida and muggid South Carolina, where your models grow mold before the paint cures.

Triarius wrote:

To insure full cure, wait at least a full 24 hours at room temperature and not more than 50% relative humidity. Force curing with mild heat and circulating air can reduce this time to an hour or two, and is especially useful in cooler, damper conditions.

I'm in Houston. It's almost never under 50% humidity here.  And I plan on cutting back on the A/C this summer.  Would you suggest running a hot blow dryer to force cure?  

Glad it worked out for you.

Andy 

Update:

So I considered using paper or post-its and thought it would be difficult to get the curves right at the wing roots.  I bought some of the low-tack blue painters tape, de-tacked it as suggested, and it worked wonderfully.  So it turns out the main problem here was the tape, not really the paint, although priming may have eliminated the trouble to start with.  Now I have some straight lines to work with and should be able to use post-its to mask for the repairs on the blue sections.  Thanks to all of your for the help.

Thanks for the tips.

Wulf, I'll try the paper or post-its.  I've actually used post-its before with good results on smaller areas.

I'd really like to salvage what I've done without stripping it down, but next time I'll be sure to use a primer. 

That's good advice from Andy and Marc, and I'd like to add some recommendations:

Model Master acrylics seem to have more trouble with adhesion than most other respectable brands. But ALL acrylics benefit to some degree from priming. Personally, I use a Tamiya light gray acrylic as primer, because Tamiya acrylics adhere very well when properly applied.

Properly applied defined: To a sterile surface. No, I don't mean use an autoclave! But the model surface must be free of all contaminants. Regardless of what you use to wash the model, the final rinse should be with distilled or deionized water—this can be just a wipe with a staturated, lint free cloth or paper towel. An alcohol rinse/wipe also works, although I would recommend using ethyl/denatured alcohol rather than isopropyl, as they evaporate faster and have a greater affinity for water. I also prefer washing in a Simple Green solution or using a surfactant cleaner. The latter, allowed to evaporate fully, sometimes helps adhesion. However, surfactant cleaners sometimes vary in composition over time. Windex (with ammonia) is a fairly reliable brand and evaporates completely.

Finally, before applying your masking, make sure that the underlying paint is fully cured. This is critical. Acrylics dry rapidly, but cure slowly, especially with regard to surface bond. This is just as true for Future (PPFTWFutureS) as for any other acylic coating you are likely to use on a scale model. To insure full cure, wait at least a full 24 hours at room temperature and not more than 50% relative humidity. Force curing with mild heat and circulating air can reduce this time to an hour or two, and is especially useful in cooler, damper conditions.

1) Clean the surface to be painted first. 

2) Prime

3) Apply a base coat, allowing it to fully cure. Acrylics may appear to dry quickly, but they are not fully cured for about 24 hrs.

4) Reduce the tack of whatever type of tape you prefer to use. Slowly remove it by peeling it back over itself.

Following these steps should solve the problem.

I almost always take the tape... blue painters or Tamiya... and stick it to theback of my hand to reduce the tack.  Then peel the tape at 90 degreess to itself when removing.

You HAVE GOT TO PRIME! That's the bottom line. Acrylics don't bite into the plastic like enamels or lacquers. The paint will lift everytime. Model Master makes a white or gray acrylic primer. Prime it and wait for 24+ hours before masking. Second, even though you wash the model, wash it really well with liquid soap. In addition, you can rub it down with some alcohol for the areas you handle a lot during construction.

The 3M blue painters masking works well if it's the DELICATE SURFACE type. It will specify on the label. I use it all the time and have no trouble.

It seems you are past the point of priming. If you have to mask, I would recommend the damp paper technique or post-it notes. For the damp paper mask, take some plain white paper, cut it to shape and dip it into some tempid water. Don't let it get soggy, just damp. Let the excess drip off and place on the model. Make sure there is no water droplets along the edges of the paper. If needed, after you place the paper on the model, let it sit and dry a minute. The water tension will hold the paper in place well enough for masking purposes. However, spray at a LOW psi and at a 90 degree angle to the surface. Otherwise you may run the risk of blowing the paper off. Right after spraying, remove the paper...pretty simple and effective. Post -it notes are excellent too. Their low tac section will not lift paint but will hold well enough to mask. Once again, low psi and 90 degrees to the surface. Hope this helps....

Andy