Paint not sticking to primer

[Robbie Tussin]

I had a very frustrating experience last night. I was finishing up a Revell Subaru STI. The paint was looking great, probably the best paint job I've done yet (thanks Treehugger Dave for sharing your painting techniques). I masked off the body to paint the black trim around the windows, which was literally the last thing I had to do before final assembly. When I peeled off the masking tape, the paint came off with it, leaving just the primer underneath. Afterward, I was able to peel most of the paint off the body in large chunks. For some reason the paint didn't stick to the primer. The primer, paint, and clear was all Duplicolor stuff. I painted it about a month ago, so it isn't like it was fresh paint. I was using tamiya masking tape, which isn't even very sticky. I must have done something wrong either prepping or painting, but I can't figure out what. Right now I'm stripping it so I can redo it and I don't really want this to happen again. Anyone have any ideas why this might have happened? Thanks!

[Modelmartin]

Thanks Treehugger Dave for sharing your painting techniques

There's your problem!!

Seriously, though, it sounds like a classic case of too much stick on the tape and not enough on the paint. Even though the Tamiya tape isn't that sticky for masking tape, it is still too much for what you are using it for. Try Scotch tap (the frosty kind) pressed on your hand once , pulled off and then stuck on your model. Bare-metal foil is good for masking window trim, too. For the paint, it almost sounds like you might have waited too long between primer and color? Lacquer does dry completely and becomes more brittle. I would have masked and sprayed the trim sooner but that isn't too critical. Even with all of my experience I still occasionally have a problem with pulling up paint. I think it is because a good model car paint job is thin and lacks strength. 1/1 paint jobs are a mile thick in comparison and hold up well.

Good luck and try, try again.

[E St. Kruiser50]

I had a very frustrating experience last night. I was finishing up a Revell Subaru STI. The paint was looking great, probably the best paint job I've done yet (thanks Treehugger Dave for sharing your painting techniques). I masked off the body to paint the black trim around the windows, which was literally the last thing I had to do before final assembly. When I peeled off the masking tape, the paint came off with it, leaving just the primer underneath. Afterward, I was able to peel most of the paint off the body in large chunks. For some reason the paint didn't stick to the primer. The primer, paint, and clear was all Duplicolor stuff. I painted it about a month ago, so it isn't like it was fresh paint. I was using tamiya masking tape, which isn't even very sticky. I must have done something wrong either prepping or painting, but I can't figure out what. Right now I'm stripping it so I can redo it and I don't really want this to happen again. Anyone have any ideas why this might have happened? Thanks!

Hey Robby

If you go back and re-read my post on painting, go to the second half, about multi-color paint jobs, there is a reference there on tape pulling up paint and how to avoid it, and there are some added benefits mentioned that'll help you too.

I posted a COOL FACED EMOTICON WITH SUN GLASSES, and arrows pointing towards the paragraph, so you can find it.....I ADDED BOLD PRINT TO THE PART ABOUT TAPE PULLING PAINT.

By the way, Tamiya tape is all I have used since it was intrduced, and HAVE NEVER HAD ANY ISSUE WITH IT - I LOVE IT .

JUST BE CAREFULL WITH THE 2" TAPE - SOMETHING ABOUT THE STICKY GUM AND ATTACKING CLEAR PLASTIC AND LEAVING A RESIDUE .

I was able to extract this from the painting thread for you.

I hope this helps

>>>> Alright, now when the priming and taping is done, we're ready for color.

I spray the sides first, two or light color coats - light and medium ONLY, just enough for coverage, as it'll be clear coated - wait 15 minutes and then shoot 2 coats of clear - LIGHT and MEDIUM to a nice gloss, but not heavy - this is called an inter-coat clear coat, and is done for two reasons.

First, this gives you a surface to tape against, AND THE PAINT WON'T PULL UP WITH THE TAPE , and second, it gives you a NEUTRAL surface to do clean up any area's on the separation line, after the second color has been sprayed, without sanding on the color surface and disturbing the color finish, even going through it OUCH !! .

Edited November 12, 2009 by Treehugger Dave

[Ddms]

... wait 15 minutes and then shoot 2 coats of clear - LIGHT and MEDIUM to a nice gloss, but not heavy - this is called an inter-coat clear coat...

I can see how this technique could save a lot of grief. Duly noted and recorded for future use.

But... just in case someone is looking for wide tape that has less adhesion and less cost than Tamiya's wide stuff, 3M Scotch makes a blue tape specifically for delicate surfaces. Unsurprisingly, it's labeled "Delicate Surfaces." I get it at my local hardware store; I'm sure it's widely available.

[Robbie Tussin]

Cool. Thanks for your suggestions guys. That makes sense to spray some clear before doing the second color. I didn't even think of that because painting the trim was sort of an afterthought. I initially tried to paint it freehand with a brush, but my hands just aren't steady enough and I made a mess.

Also, I think I probably did wait too long between primer and paint. It was probably at least four or five days after I primed before I painted it. I followed the time frame between coats of paint that treehugger dave laid out in his tutorial, but it didn't occur to me that I have to do the same with the primer. Once the first little piece of paint came off, the rest just practically fell off like it wasn't stuck at all. Oh well, at least it made stripping the body really easy. I just rubbed it with a toothbrush and took almost all the paint off the body. Its just about ready for attempt number 2. Hopefully it works better this time.

[E St. Kruiser50]

Also, I think I probably did wait too long between primer and paint. It was probably at least four or five days after I primed ....

In my experience you can never let primer dry too long. 5 days is usually about how long I let it dry anyway, before the final sanding.

But as someone here suggested, you may have gone TOO FINE ON THE SANDPAPER, when you prepped the primer.

I never go finer than 800 grit, with wet or dry paper.

I usually sand dry, before shooting color.

[Ddms]

I never go finer than 800 grit, with wet or dry paper.

Neither do I, but only because it's more efficient. With U-POL and Tamiya TS-Series syn lacquers, "key" or "tooth" has no effect on adhesion. The coats melt together, so the next coat will stick regardless.

Yet another good reason for using syn lacquers instead of enamels and acrylics.

[BigGary]

Here's my 2 cents. How much did you handle the car while primered, and was it left where any kind of oil base substance could land on it? Oil from hands and smoke from grease in the kitchen could be on there and you might not know it. Also, your paint could have been contaminated with something. I don't know, but just suggestions.

Gary