Masking tape peeling paint off of primer - what'd I do wrong?

[TheCowGod]

Hey guys. My name's Dan, and I'm in Knoxville, TN. I've been browsing around here quite a bit, but this is my first post. I recently built an EA Tremolo on perfboard and put it in an unfinished 1590B. It works great and was a good learning experience, so I decided to try my hand at painting the enclosure to start learning how that works. Given that I like cows, I went with a cow-spotted look, figuring I'll call the pedal a Tremoolo. That obviously called for coating the whole box in white, followed by masking out spots and then painting the black.

Based on the info I found here in the FAQ, I used self-etching primer and lacquer paints:



I sanded the enclosure with 400 grit sandpaper, then did two coats of primer, waiting about 2 hours between coats. Then three coats of white, waiting about an hour between each coat:



After the third coat, I let it dry overnight. In the morning, I masked the cow spots with blue painter's tape:



Another light coat of white (I remember reading that this can help keep the next color from seeping under the masking tape):



Then a coat of black on the top of the enclosure, wait an hour, turn it over and do two coats of black on the bottom -- 10 minutes between coats, and then an hour to let that set. Then turn it back over and one final coat of black on the top, and I let that dry for about 2.5 hrs.



After those 2.5 hrs, I tried to peel off the masking tape to start working on decals. The tape came up OK in some places, but it pulled up the white paint off of the primer in most others. The primer still looks great, but the white paint didn't seem to stick to the primer very well at all. I can just pull the paint off in whole sheets.



So any idea what my mistake was? I'm eager to try again. What should I do differently next time? More drying time? Thinner coats? I definitely succumbed to the temptation to apply too-thick coats. I'm also unsure about the air temperature -- it's about 40-50 deg F outdoors, so I did this in my closed garage, which is probably closer to 60, but still pretty cool. I set my space heater blowing on the enclosure whenever I was in the garage, but didn't feel comfortable leaving it running for hours unattended.

I understand lacquer doesn't require baking, but maybe it'd make more sense to buy the cheap toaster oven and use whatever types of paints do require it (enamels? ) ? I'm open to whatever direction makes the most sense, I'm just not sure what to try differently the second time around. Guide me, oh internet Thanks for this great resource, I've learned so much so quickly, just by browsing around and reading threads.

Dan

[linny1982]

hi dan. i'm new around here to but i've been painting lots of different things for years. with tin spraypaints the lighter the coats and the longer you let them dry the better. it may also help if you let the primer dry 24hrs or more and give it a wet sand with 400 grit (being carefull not to rub through on the corners). this will key the surface and give the paint something to hold onto. only other thing is to make sure you use low adhesion tape. if your tape is to sticky just stick it to a clean surface first. it will remove some of the adhesive. hope this helps

andrew

[alanlan]

Looks to me like the paint ain't compatible with the primer as it has come clean off.  I don't see why anyone should need to sand primer except to remove any rough bits of dust which have settled on the surface etc.  Primer is designed to be painted on top of without too much extra hard work as long as you keep it clean inbetween.

[Quackzed]

++if your doing cow spots or taping off some spots, remove the tape when the layer of paint over the spots is still WET.
once it dries, the paint will be too solid and will not tear or let the tape go...it'll pull up the paint around it...
it might simply be risky to tape up a very recently painted anything...
    although drying times are printed on the can, most paints require a long time before they fully cure.
I paint paintings in oil, and one of the hard facts is that they requre a LONG time to cure.
on the order of months to years. no kidding. (museums see oil paintings as ' fully cured' only after like 100 years.
i mean you can usually handle them carefully in a week, but thats just the surface of the paint...
granted, spray paint doesn't take THAT long, but it still takes some time...
    if you want to tape it up, let it cure for at least 3-4 days first, and for extra safety, hit it with a layer of furniture polish or car wax before taping. don't leave the tape on long,, as tape cures too.
...also, for better paint adhesion you could prime then let dry then, sand the primer, just enough to get rid of the shiny smooth surface and give the next layer of paint something to grip. being carfull not to sand 'through' the primer.
   also, laying paint on thickly will leave uncured paint beneath a skin of "dry" paint. so things will look dry, but wont BE fully dry. make the first few coats of color on the primer
very thin, like misty. not fully covering the primer, let set (read can drying times) hours. another mist coat, (dry) then you can do a first thin coat of color.
-- whatever you do, don't frighten or anger anything you've just painted.
-- paint like your feeding a fish.

[TheCowGod]

Hmm, OK. Yeah, this blue tape is supposed to be less sticky than regular masking tape, and I stuck it all down onto a cutting board first to cut out the spots before peeling it up and sticking it on the enclosure. Maybe this time I'll use a surface that it can stick to a little better, to get more of the adhesive off.

Yeah, before starting the paint, I tried sanding the primer with wet 400 grit, and it seemed like it immediately started getting back down to the bare metal, so I stopped. I think I might get the rest of this white/black paint off, do another coat or two of primer, and let them dry a full day before I start with paint. Then I'll do as you guys suggest -- a few light coats of paint that don't fully cover the primer first. That was my main problem -- when I'd do the first coat of paint in a new color, it bugged me to see just a light speckling of it with the previous color showing through, so I'd keep applying till it covered it. I'll have to resist that urge.

Man, patience has never been a strong point of mine Historically I haven't really put effort into making my projects look nice either -- once it works, that's good enough for me. But seeing all the amazing-looking pedals you guys have posted has encouraged me to try making something look pretty for once in my life Thanks for the input, let's see how this goes the second time around.

Dan

[TheCowGod]

Although interestingly, the remaining white/black paint is a lot harder to get off of the primer now after another night's drying. Think I'll have to just sand it off. So I guess my other lesson is to give each coat longer to dry. Dry to the touch really doesn't mean that it's fully dry. We're learning! Thanks guys

Dan

[davent]

I second, third the motion for many light/dry coats of paint. You might also want to drop by an art supply store and pick up a sheet of frisket film, which is a very low tack semi clear sheet used for creating masks. Around here you can buy as little as an 8x14" sheet or rolls of the stuff. Never had paint lift using it for masking.

dave

[ItZaLLgOOd]

I'll stick the tape on my jeans or my shirt before I apply it to an already painted surface.  I've never had a problem.

[TheCowGod]

I sanded most of the color off, did another 3 coats of primer, letting each one dry for several hours, then wet-sanding with 600 grit before beginning the paint. This time around I went much slower, doing thin, light coats and leaving several hours between coats:



I let the primer dry overnight before starting on the white, and let the white dry overnight before masking and painting the black, and I let the black dry overnight before peeling off the masking tape. This time it worked BETTER, in that it didn't peel up the paint EVERYWHERE, but the paint still peeled up in 4 or 5 places, and from there it spread pretty quickly. Sigh.



Then I noticed this note on the roll of tape:



"Do not use on lacquer." Hmm.

I think I'm going to try frisket film as davent suggested, but even so, I think it's time to change paint types. I picked lacquer paint because this post suggested it, but it seemed like lacquer paint was sort of a compromise just to avoid having to bake it in a toaster oven -- the only colors I found lacquer available in where black, white, and clear, which fortunately happened to be the only colors I needed for this project. But it seems like it's not worth the trouble -- I certainly don't mind the $10 expense for a cheap toaster oven.

So what's a good alternative? Enamel?

Dan

[jacobyjd]

Something to consider--

It looks like you're only waiting overnight. Without baking (to accelerate gas-off), I've had spray paints (acrulic and enamel) stay tacky for over a week before. you may want to try giving it a full 24 or 48 hours before applying the tape.

[pjwhite]

Another thing to consider is how well the bare metal is cleaned before the first coat of primer.  If there is ANY dust, oil or other contaminant on the surface, it will lessen the hold of the paint, and be more prone to flaking or peeling off.

After the last sanding, clean the surface thoroughly with contact cleaner, acetone, 99% alcohol or some other solvent that will evaporate completely.
And bake the paint, too.

[Quackzed]

hmmm.
you need to remove the masking (tape or frisket etc..) before the paint on top of the tape dries.

i think this was your only mistake...

you said...                " I let the black dry overnight before peeling off the masking tape."

if you had sprayed the black over the tape  then immediately  removed the tape while the black paint was still wet, the tape would have come off easily.

maybee you can peel off the whole top layer and try  again, and not have to go all the way back to the beginning?

[newfish]

Am just getting into the fancy-pants painting you guys do and have learned a ton from this thread already.

FWIW, if you don't have access to Acetone etc. (nail varnish remover...), I've been very lucky so far with a domestic vinegar solution (strong one!).

1 part Vinegar to 1 part water.  I wash the plain, sanded boxes in this before patting dry with paper towels (yes, I know - stray fibres and all...)

So far, my Primer has bedded down quite happily.

I do leave it for a day or two between coats though.

Might treat myself to a Toaster Oven soon.  I'd really like to have 'shiny' boxes one day...