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-   -   Blue masking tape: How long to leave on? (http://www.diychatroom.com/f4/blue-masking-tape-how-long-leave-25127/)

digexpressions 08-12-2008 08:29 PM

Blue masking tape: How long to leave on?
 
I am going to be painting around the windows in my office and have taped around the casing. How soon after painting the walls should I remove the tape? I will most likely be doing two coats. The reason I ask is the last time I did this, when I went to remove the tape, the paint started peeling and coming up with the tape. Should I have waiting longer for the paint to dry harder? Or should I have removed it shortly after the second coat so that the paint didn't dry as thick? Trying to avoid the same thing happening. Thanks!

Nestor_Kelebay 08-12-2008 10:53 PM

That happened to me this summer as well.

I think I solved the problem by changing primers. I was painting over bare wood and used Zinsser's Bullseye 123 as the primer, followed by two top coats of a exterior flat pretinted brown. I had a heck of a time with the paint pulling off with the tape, and when the paint pulled off, it left bare exposed wood, not primer. That indicated to me that the problem was at the wood/primer interface, not the primer/paint interface.

Next time, I used a local paint company's (Northern Paint) exterior latex primer and two top coats of the same exterior flat pretinted brown, and NONE of the paint pulled off with the tape.

I think the problem is that Zinsser's Bullseye 123 is not only real sticky, but it sticks better to the painter's masking tape than it does to the bare wood (or other substrates, too). I was painting window frames on different sides of my building, and some of the difference could have been due to the different exposure to the Sun, too. Also, when using the Bullseye 123 we had good weather and we top coated only a few hours after priming. With the locally made primer, it rained a few hours after we primed, so we didn't top coat till the following Monday (cuz my nephew was doing the work). I really don't see how the rain or waiting period would have affected the problem, tho. I'm thinking the biggest hunk of the problem was from using a primer that stuck better to the tape and itself than it did the bare wood. The other primer didn't do that, so maybe it doesn't stick to itself or the masking tape as well.

I always pull the tape off as soon as we finish the second top coat. We did that in both cases here, too. I can see that this would help because perhaps the second coat hadn't even formed a film when we pulled the tape off, so the second coat at least didn't contribute to the problem. But, me thinks the problem is more with the primer than the paint anyhow, and so my best guess is that asking how long to leave the tape on is the wrong question. I think if you use a different primer, it won't matter how long you leave the tape on, you'll get equally better results.

Try a different primer.

EPI 08-12-2008 11:14 PM

I don't usually use tape since it gives one a false since of giving a straight line.

I think the problem might more be that the coating hasn't cured all the way it usually takes 24 to 48 hrs for a coating to cure. but to be on the safe side you should take a blade and cut around the edges. This will cut the coating between the tape and frame.

sirwired 08-13-2008 10:28 AM

Really for things like window casings, you should not use tape at all. Why? First, as you discovered, you can pull off the paint underneath. Two, paint bleeding under the edges of the paint can be an unsighly problem, that can only be prevented by burnishing the tape against the surface, which causes even more peeling on removal.

Get yourself a Purdy 2 1/2" Angle Sash brush, take a deep breath, and do the lines free-hand. This is called "cutting in". There are a zillion videos on YouTube on this if you need some tips.

I only use tape for knobs, hinges, and stained woodwork.

SirWired

slickshift 08-14-2008 04:56 PM

Well, tape should be used to avoid splatter on trim, not as a tool to cut lines
Sometimes people tape and think they can wave the brush in the general direction of the corner and think the tape will "make it work" and look fine
In reality the tape used in that manner will nearly always lift something

If using the tape properly, and little or no paint gets on it, then the time to leave on is marked on the tape package
Some can be removed cleanly after a week or so, some nearly a month
Either can lift paint if the paint is blobbed on there


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