I had the hull glassed with 2 fill coats, should have done 3. I then put the deck on, glassed it, scored the first layer at the tape line and pulled the tape/fiberglass off. Everything was going great. Next, I let the epoxy cure for about 3hours. I then wiped the hull down (denatured alcohol)avoiding the fresh layer. The hull was sanded but looked like it could use some more fill coats so I thought when I was filling the weave on the deck I would add another coat or two on the hull at the same time. After the first fill coat I noticed that the epoxy where the tape was was not flowing right. I tried rolling it more thoroughly but to no avail. It appears the denatured alcohol did not remove the adhesive residue. I’ll add photos. Apparently I should have used something else to wipe the tape residue off, maybe lacquer thinner or something else? I’ve sanded it all back down and certainly don’t want this to happen again.
Yeah, tape residue is nasty and the longer it stays the nastier it gets. Denatured alcohol does nothing about it. The only way I’ve been able to wash it off is with some kind of petroleum distillate, which itself doesn’t play well with epoxy. So sanding is your best bet.
If you must put tape on bare wood keep in mind that:
- You shouldn’t press hard; that works the adhesive residue into the pores.
- A fine line masking tape leaves less residue than most other types.
- You need to get the tape off the bare wood as soon as possible.
Laszlo
Ouch!
tell us more about the tape. i use tape in a lot of steps…and as laszlo says, you need to be careful of residue.
that said, depending on the particular part of the construction, i have, through the school of hard knocks, developed some approaches that have minimized those knocks…that i would be happy to share. i just can’t figure out from your description, what was the tape application step that created the residue problem (e.g., were you using tape to mask an area, were you using tape to hold something in position? some other step?). And to the extent you can clearly identify the substrate (wood, epoxy, a painted surface) and what you expected to do on the surface after the tape removal (more epoxy, paint or varnish), that would be helpful.
without the specifics, some general conclusions i have from a lot of builds are:
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pay for good, “fresh” tape from reputable brands like 3m. …which generally, relative to their use, leave little residue
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do not leave tape in place any longer than needed (the longer its in place, the more likely to leave residue than not and
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inspect after tape is pulled to ensure that you have a clean surface prior to the next application (could be paint, or more epoxy, or varnish) and to use the right cleaner in anticipation of that step.
i hope, absent more details, that this is helpful.
h
Thanks Laszlo and Howard,
The application that I was using the tape for was to protect the epoxy/glass surface on the hull from the raw fiberglass that I was applying to the deck. This makes for cutting a clean line after coating the deck. I was using blue painters tape. I will use 3M tape whenever possible, I’m a big believer in 3M products. The tape had been on for maybe a week. I have since sanded everything back down including the deck and hull. The instructions call for wiping the cured epoxy surface down with lacquer thinner but not specifically for removing tape residue. I’ve been using denatured alcohol which I believe was a mistake. I will try this for the next 2 fill coats keeping a close eye out for “alligator skin” is best description of it. You can see the blue tape under the raw cloth in the first photo.
One suggestion of last resort when an epoxy coating is going bad… I’ve never had as bad an event as your pictures show, but over the years have hit a contaminated (non-stick) patch or two that became evident during coating, or more frequently pushed a little too long in trying to use epoxy that was setting up, and thus got stringy and milky in the final spreading process. I’ve found it better to grab a well-wet alcohol rag and scrub the bad stuff off right away. The result can be that less effort is required to sand out the more minor “washed off” area blemishes prior to the next recoating. For me this seems to save time on sanding, and limits the chance of creating sand-thru’s or a wavy surface as you try to sand off aligator skin/orange peel, or milky-stringy epoxy patches that you’ve let harden in place.
Doug,
All is clear now. I use that same technique, just with different tape - 2" wide clear plastic packing tape.
I also typically leave the tape on the boat for less than a day. If it’s a hot day build, it can be only a few hours. That’s not enough time for residue to become a problem with that particular tape.
I think that you’ve also got something else going on there - the type of tape. That blue painter’s tape is more textured so that epoxy sticks to it somewhat. I don’t know if that interacts with the adhesive in forming residue. I do know, however, that I’ve never had an issue with the packing tape over multiple boats. I’d recommend that you switch to that in the future.
Laszlo