Damned weatherman...

[travlineasy]

The local weather doodle predicted mostly cloudy and 85 degrees for yesterday, zero percent chance of precip. Well, it was mostly cloudy, about 85 degrees, and because there was no rain in the forecast, I spent the better part of 5 hours and two rolls of blue masking tape, preparing the boat for painting the slick surfaces between the rub-rail and toe-rail. Today's forecast was for clear, light winds and about 75 degrees--perfect for painting.

Well, last night about 2 a.m. the thunder boomers rolled through, the rain came down in torrents, but only lasted about 20 minutes. This morning, the sky was 100-percent overcast, temperature was 51 degrees at 9 a.m., and the forecast was for temperatures to rise to about 60--much too cold and damp for applying two-part, epoxy paint. The next, forecasted , warm, sunny day is this coming Thursday (keeping my fingers crossed).

Based upon the knowledge that I cannot be the only person on the forum that has ever experienced this type of problem, I have a question: How long can I leave that blue masking tape in place before it leaves lots of sticky residue behind? Most of it is applied to hardware--not on the fiberglass. But, there are a few short stretches of about 3 feet where it is on the glass.

Also, the paint it Petit, which was purchased at West Marine. Should I remove the masking tape while the paint is wet, or should I wait for it to dry before removing it. I asked the good-looking, young gal at West Marine, but she didn't have a clue what I was talking about.

Thanks in advance,

Gary

[msmith10]

Could be worse, Gary. The girl at West could have been homely.
If it was good quality tape you should be able to leave it on for several days without worrying about residue. I like to remove it after the paint is well into the tacky stage but before it gets really hard. That way if it scrapes against the new paint it doesn't bung it up or get stuck in it. If you're not fussy you can take it off as soon as it is tacky and won't run.

[c25novi]

Weatherman - I always get a good laugh at the 5 day forecast, around here there's less than a 50/50 chance they can predict today's weather right!

Paint tape - I've had problems with leaving the tape on too long and then the paint doesn't split evenly along the tape line taking too much paint off :-(

I wait for about an hour and put on some gloves and remove the tape while it's still pretty wet. It's messy and you have to be very careful but it leaves behind a nice sharp line.

[smurphny]

The blue tape will come off even after a 3-5 days but I wouldn't leave it any longer. It's a real bear to get off once it chemically bonds to the paint. I spent an hour this morning with acetone getting some regular masking tape off that sat for two days, got wet and dried on!! The upper level air pattern is still rotating around the stubborn Canadian maritime low which has sat its a$$ over the NE for a month now. It keeps pulling cold air down from Canada. Has been below freezing in this neck of the woods at night and mostly cloudy, cool and damp most days for the last few weeks.

http://weather.noaa.gov/pub/fax/PPAE11.gif

[travlineasy]

Thanks everyone for your help. I hope to get the painting done by late tomorrow afternoon and remove the tape right away.

Thanks again,

Gary

[Flybyknight]

Originally Posted by msmith10

Could be worse, Gary. The girl at West could have been homely.
If it was good quality tape you should be able to leave it on for several days without worrying about residue. I like to remove it after the paint is well into the tacky stage but before it gets really hard. That way if it scrapes against the new paint it doesn't bung it up or get stuck in it. If you're not fussy you can take it off as soon as it is tacky and won't run.

That's the way I see it also.
Dick

[TakeFive]

I think that blue tape is rated to be removable for 2 weeks, but that may just be for interior applications. Temperature and moisture fluctuations outside may shorten it.

I would be more concerned with your decision to use the blue tape in the first place. I use the blue tape for rough edging only. If you plan to paint onto the tape and pull it off to create a fine line, you might be better off with the green-yellow "line tape."

[Barquito]

I have a question about taping: If you are going to be putting 2 coats on, do you remove the tape after each coat? I might need to wait a week between coats.

[CarbonSink62]

If I paint twice, I tape twice. It can be tough to get the same line; life is like that.

I hear the 'frog tape' is really good. Anyone used it?

[TakeFive]

Originally Posted by Barquito

I have a question about taping: If you are going to be putting 2 coats on, do you remove the tape after each coat? I might need to wait a week between coats.

This depends very much on the type of paint.

If the paint is formulated to have relatively little cohesive strength, like ablative bottom paint, you can leave the tape long after the paint is dry. You could easily do 2 coats a week apart without re-taping.

If, however, the paint is formulated to make a durable film with a lot of cohesive strength, you would need to remove the tape before it fully cures, otherwise you might chip the edge or, worse, peel a large film off the substrate. The epoxy example mentioned above is a good example of this. Epoxy cures to a very strong film, which necessitates removing the tape when it is at the gelatinous stage.

For multiple coats, tape is not your only problem. A paint that cures (2 part epoxy, 2-part isocyanate like Awlgrip, air cure enamels, etc.) can have poor inter-coat adhesion. You either need to do the second coat within a day or so (when there is still enough residual uncured content for the coats to chemically bond) or scuff sand between coats to give something for the second coat to grab onto. I believe that many solvent based bottom paints are lacquers (not emanels), so they don't actually cure - the solvent just evaporates off leaving a dry film that could be redissolved with the proper solvent. For these paints, the solvent from a second coat "strikes into" the prior coat, giving pretty good adhesion even after the prior coat is dry.