Painter's tape sticking to new caulk

I just finished some outside painting and am having a problem with painter's tape that is sticking to new caulking around windows. It's latex type caulk that was applied a couple weeks ago. Then painter's tape was applied recently over it to mask off the windows. The caulk, while cured enough for painting, etc, is apparently not cured enough to keep it from bonding to the tape. I spotted this problem and even switched to the lowest adhesion painter's tape for delicate surfaces. Even so, after one to two days, it's sticking to the caulk underneath and when you go to pull it off, it starts lifting the nice smooth caulk job up with it. Doesn't seem to actually pull the caulk out of a gap, but it does rough up what's there, make it stringy, a mess, etc.

Any ideas on how to get it off? I tried using a hair dryer, no effect. I tried removing it on mornings when it was cold, no effect. I tried brushing on some mineral spirits, that might have helped a little. I even bought some Mossbacker's super special stuff that was highly rated for removing tape, gum, etc. No effect. I think part of the problem is that the tape now has paint over top of it too, so it's harder for anything to penetrate. I was thinking of trying either multiple coats of mineral spirits over a couple days or possibly acetone? Of course one main concern is that I also don't want to damage the new paint. The tape is just on the metal window frame, but still some small amount of anything I use is going to get to the very edge of the paint.

I would think this would be a common problem, caulking then taping, painting is done a lot. But can't find anything about it. I guess one way pro painters probably avoid it is by putting up two coats of paint, same day, then removing the tape right away. But being DIY, weather, etc, I've typically had at least 2 days between putting it on and taking it off.

Any ideas?

Reply to
trader_4
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Remove within 24 hours of taping. AND keep out of sun!

I found 6 year old paint came off using that blue painter's tape. I had a shelf board to paint, so lenaed it up against a blank wall, placced about

3 inches wide of tape to prevent painting the wall, only to find.. that the paint that got onto the tape evidently diffused right through softening the fairly old [at least should be cured in 6 years!] When I pulled the tapeoff, sure enough paint came off in the pattern of the paint on top the tape! I mean pulled off, too.
Reply to
RobertMacy

I think the bottom line here is that you put the tape over the caulk before it was dry enough.

Acrylic latex caulks don't have a chemical curing process like polyurethane caulks or oil based paints. Instead, they undergo a physical transformation as they "dry", exactly like acrylic latex paints do as they "dry".

I'll explain the physical transformation that occurs in latex paints, and exactly the same thing happens in acrylic caulks, but with different solvents and different resins:

A latex paint consists of a slurry of solids suspended in a liquid.

The solids consist of:

  1. Hard transparent and colourless plastic resins made of one of two kinds of plastic

  1. coarse solids called "extender pigments" that cause the paint to dry to a rougher finish. Were it not for extender pigments, all paints would dry to a high gloss finish.

e. fine solid particles called "coloured pigments" that give the paint it's colour.

The liquid those solids are suspended in consists of: A. water, and B. a low volatility water soluble solvent called a "coalescing agent" or "coalescing solvent". Probably the most commonly used coalescing solvent is a product called "Texanol" made by the Eastman Chemical Company.

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C. glycerine, which is added with the colourants called for in the tint formula when the paint is tinted at the point of sale.

When the paint is applied to a wall or ceiling, the first thing that happens is the water starts to evaporate. As the water evaporates, each of the hard spherical plastic resins finds itself in a bath of coalescing solvent at steadily increasing concentration. The coalescing solvent gets absorbed into the hard clear spherical plastic resins causing them to become very soft and sticky.

The forces of surface tension and capillary pressure which cause tiny droplets of water to coalesce into large heavy rain drops then take over to cause each soft sticky plastic resin to stick to and pull on each of it's neighbors. As that happens, there is a rapid reduction in the number of liquid/plastic interfaces which reflect and refract light to produce the colour white in an observers eyes, and the paint film darkens slightly as a result.

In proper film formation, all of the soft sticky plastic resins pull on each other with sufficient force to eliminate the phase boundaries around each resin, and the result is a solid soft sticky film of clear plastic with the extender and coloured pigments suspended in it very much like raisins in raisin bread.

Then, over the next 12 to 48 hours, the coalescing solvent evaporates from the paint film filling the room with that "freshly painted smell". You can create that freshly painted smell in any room simply by using a spray bottle to mist some Texanol into the air.

As the coalescing solvent evaporates from the paint film, the plastic hardens up again to the same hardness the plastic resins originally were in the liquid paint before the can was opened. Only, instead of being microscopically small spheres of plastic, they now consists of a continuous solid film of plastic with pigments suspended inside it.

The above explains why latex paints darken as they dry. Initially, there is reflection and refraction of light at every plastic/liquid interface, and so latex paint is white for the same reason that clowds and snow is white. Your eye sees all the different colours of refracted and reflected light coming from everywhere in the paint film as the colour "white". As the plastic resins coalesce into a solid film, there is a rapid reduction in the amount of reflection and refraction of light within the paint film, and the paint darkens in very much the same way that snow loses it's white colour as it melts to form water.

Also, over tinting the paint with too much colourant can ruin latex paints. The reason for this is that the coalescence process requires that the concentration of coalescing solvent in the plastic resins become high enough to fully soften the resins so that they deform easily to form a solid continuous film with no voids in it. If there was too much glycerine added when tinting the paint, that will dilute the concentration of coalescing solvent in the wet paint film after the water evaporates. The concentration of coalescing solvents might not be high enough to soften the plastic resins sufficiently that they deform easily enough to form a solid continuous film.

And finally, painting with a latex paint in cold temperatures can be problematic because every plastic gets harder when it's cold, and the cold temperature can make the clear plastic resins too hard to soften sufficiently from the absorbtion of coalescing solvents alone. That's why you're not supposed to paint when the outdoor temperature will fall below 50 deg. F at night.

What very well may have happened is that by pushing the tape on the "dry to the touch" caulk, you prevented the remaining coalescing solvent in the caulk from evaporating normally from the caulk. The result would be that the plastic resins at the surface of the caulk would have turned softer and stickier as they absorbed coalescing solvent for a second time. If you pushed the painter's tape onto those sticky resins, they would have stuck to the adhesive on the tape, and your now pulling that tape off is taking chunks of acrylic caulk with it.

I don't see any way around this problem. The resins are sticking to the tape adhesive just as they would wood or glass. I'd say your best bet it to just pull the tape off, and paint over the caulk so that it sheds water easily. I'm concerned that if you leave the caulk rough, then water will collect on it and mold will start growing in those collection points. Better to paint over the caulk so that the water drains off the paint surface after a rain.

Next time, allow more time for the caulk to dry before applying the painter's masking tape.

Reply to
nestork

That the caulk was not fully cured was my first thought too. But as I said before, in some cases the caulk had two weeks+ to cure, including days that were 60s, even 70s. And I don't see any difference in how the tape then stuck to those caulked spots versus how it stuck to caulked spots that had ~3 days to cure. I still think that you're right, if the caulk was on there for a year, then the tape probably wouldn't stick. But I would think painters would be having this problem all the time, because I doubt they caulk, then wait more than a few days. I have seen painters say it's best to remove the tape as soon as the paint is dry to the touch, but they didn't go into anything beyond that. I was thinking that they were just referring to the fact that with any tape, if you leave it on too long, especially in the hot sun, etc, then it can be difficult to get off. But I wasn't prepared for this bonding to the new caulk thing in just one or two days problem.

Reply to
trader_4

In news: snipped-for-privacy@googlegroups.com, trader_4 belched:

Try some naptha, I also use WD-40 to remove spray adhesive from my hands, so you might even try some of it or just kerosene

Reply to
ChairMan

Reply to
LHolen

I just had the same thing happen, froggie painters tape, caulk 2 weeks old, 58 degrees, rough sawn ceder, latex paint, tried to take the tape off as s oon as i finished a window area (?twenty minutes), pulled out big pieces of caulk even from the joint. Did anyone try treating the caulk first with ve g oil?

Reply to
LHolen

d, 58 degrees, rough sawn ceder, latex paint, tried to take the tape off as soon as i finished a window area (?twenty minutes), pulled out big pieces of caulk even from the joint. Did anyone try treating the caulk first with veg oil?

IDK how you treat caulk around a window with oil and not have it interfere with applying the paint. How do you keep the oil only on the caulk, withou t it being on the adjacent wood? And how will tape then stick to it at all?

Reply to
trader_4

Same problem. New windows with cedar wrap. Yellow froggers tape. Caulk had about 2 to dry before I taped and painted. Not pulling off caulk. Will probably just have to recalk. I don't see any other way to fix it.

Reply to
TDiaz

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