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Author Topic: Painting woes part duex  (Read 149 times)

Offline MSgtUSAFRet

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Painting woes part duex
« on: March 08, 2019, 08:05:35 am »
Hey Gurus,

I have had a terrible time with trying to get my Enterprise C painted. See my thread starting here for more details.

So I had stripped the model down to the primer using rubbing alcohol and, after some time allowing the alcohol to driy, I applied Vallejo Model Air paint to the ship. The paint on the secondary hull and the primary hull seem to be stable and staying in place.

However, when I went to mask the pylons, and cutting away a portion of the mask, the lifted up with the Tamiya masking - an issue I haven't had with on the other section. The primer stayed in place, but the paint did not.

I painted using recommended pressure and thinning mix, I used a hair dryer on lowest heat setting to help set the paint, I let the paint dry longer than 48-72 hours before trying to mask or handle the model piece. Humidity was high - it always is in my location - but using a hair dryer was thought to compensate for that. It was cool at the time of painting, but not jacket weather or worse.

I dunno what is going on and, TBH, am "one more time in the spray booth" away from setting this venture aside and moving on; which is a shame considering the work I have put into this and the time spent.

I would love to read your thoughts.

Thanks for the help,

Steve
"To be honest with you, Picard, a significant number of my crew members have expressed a desire to return even knowing the odds. Some because they can't bear to live without their loved ones, some because they don't like the idea of slipping out in the middle of a fight."

Online Tiburon

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Re: Painting woes part duex
« Reply #1 on: March 08, 2019, 07:02:32 pm »
Sorry you are having such a bad tine with the paint. Do you use adhesion promoter on your paint?

The first model I made was a 1/72 scale space shuttle. I did not use the adhesion promoter and  as a result the paint peeled with the tape in some places. Had to redo.

Is the primer a different type of paint from the base color? I was wondering if maybe it is having trouble adhering to a different type of material acrylic vs lacquer etc...?
« Last Edit: March 08, 2019, 07:05:26 pm by Tiburon »
Phil

Offline simi

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Re: Painting woes part duex
« Reply #2 on: March 08, 2019, 09:44:19 pm »
Hmm, what kind of primer were you using?  Seems like you dotted the I's and crossed all the T's on this as far as taking the right precautions.  The one thing you didn't mention that could possibly be the issue is the layer thickness.  If you throw on really thick layers of paint, it will tend to lift more than if you do multiple thin layers.  I occasionally get lifting but that's usually the cause.  Multiple thin layers FTW.  The fact that the primer stuck but the paint lifted to me kinda points towards that. 

Also - how long did you leave the tamiya tape on the kit for?  I try not to leave the masking tape on too long (basically as soon as the paint is dry enough to touch safely I carefully remove the tape).  Not sure if this is something to be concerned about - but I've recall hearing that keeping the tape on for a long time might cause it to pull up the paint more too.

 
Cheers!

Simi
« Last Edit: March 08, 2019, 09:47:57 pm by simi »
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Offline Spencer

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Re: Painting woes part duex
« Reply #3 on: March 09, 2019, 09:33:33 am »
Interesting that it didn't happen on the other areas you mention. It sounds like the acrylic didn't adhere to the primer on the pylons as well. Hmm ...

In addition to what Tiburon and simi said:

Am I right in that you've already stripped the color off once? If so, did you sand the primer, or try to strip that at all? I've found that you need your primer
coat to be as uniform as possible and not really "messed with". I usually put a final light, unifying, pass of primer down before I spray my color. A residual
fleck of previous color, or dust, or residual fingerprints will create weak points that can then snowball.

Second, did you de-tack the Tamiya tape? In my play arounds with Vallejo, I've found I need to run the tape across my work surface or the back of my hand
to reduce the tackiness. I've had little lift when doing that.

Third, humidity could still be the cause. If you really dig into Vallejo's literature, somewhere, it says permanency can take several days, if not a couple weeks.
You really don't have to wait that long, and that's where using multiple, light layers is really important. But if the other areas you painted behaved, then it might not be the problem.

Don't be deterred! Sometimes, paint lift is just the game you play with acrylics.

Spencer


P.S. A thin layer of clear can also help to keep the paint underneath from lifting. A clear matte with "tooth" for the upper layer to adhere too.
« Last Edit: March 09, 2019, 09:40:02 am by Spencer »
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Offline Shawn McClure

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Re: Painting woes part duex
« Reply #4 on: March 10, 2019, 11:55:06 am »
Man, this painting stuff is a pain.  Sorry you are having trouble Steve.  And... as usual... I have no advice for you.  You are so welcome.   :o
Sorry you are having problems though.

Shawn
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Offline Decoman

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Re: Painting woes part duex
« Reply #5 on: March 10, 2019, 03:25:49 pm »
I am no expert, but I never trust the adhesive qualities of Tamiya masking tape, to never tear off paint.
So, I always place the masking tape on my hand, to remove some of the adhesiveness.

Offline MSgtUSAFRet

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Re: Painting woes part duex
« Reply #6 on: March 11, 2019, 07:49:38 am »
Sorry you are having such a bad tine with the paint. Do you use adhesion promoter on your paint?

Is the primer a different type of paint from the base color? I was wondering if maybe it is having trouble adhering to a different type of material acrylic vs lacquer etc...?

Phil, thanks for the response! No, I didn't use an adhesion promoter; despite being advised to do so. Guess I'll get some. Naive me assumed the paint basic paint would have that already mixed in. Lesson learned. The primer was Krylon primer for plastic sold at Walmart. Since I applied the primer in Nov 2017, there shouldn't have been an issue with off-gassing; only the window for adding an over-coat had long since passed - I think it is around 48 hours following application of the primer. I've read where I should have stayed in the same "family" /brand as the paint but, didn't.

The one thing you didn't mention that could possibly be the issue is the layer thickness.  If you throw on really thick layers of paint, it will tend to lift more than if you do multiple thin layers.

Simi, thanks for your response! I do seem to have an issue with this; I tend to want to cover in one go. I know better. On the + side - I did try another spot with a different color paint and made sure to dry between layers. I also sanded the surface of the primer to promote adhesion. It "seems" to be working better. Haven't really tested it yet to assure the validity of that statement yet either, so...

Also - how long did you leave the tamiya tape on the kit for? 

Simi, in this case, I applied the masking over the area, cut it away to reveal the area to be painted and, when I removed the tape, it peeled up the paint. grand total of 7-10 mins in contact with the paint?! Although, now I am concerned that the tape I have left on the saucer for nearly a week, as I am working to mask for the third paint color this week and intend to mask out the secondary color. If that makes sense. The initial saucer masking with have been in contact with the base coat for nearly two weeks once I get everything said and done. sigh. Guess I'll be careful in removal and expect touchups.

Am I right in that you've already stripped the color off once? If so, did you sand the primer, or try to strip that at all?

Second, did you de-tack the Tamiya tape? In my play arounds with Vallejo, I've found I need to run the tape across my work surface or the back of my hand
to reduce the tackiness. I've had little lift when doing that.

Third, humidity could still be the cause. If you really dig into Vallejo's literature, somewhere, it says permanency can take several days, if not a couple weeks.
You really don't have to wait that long, and that's where using multiple, light layers is really important. But if the other areas you painted behaved, then it might not be the problem.

Don't be deterred! Sometimes, paint lift is just the game you play with acrylics.

Spencer


P.S. A thin layer of clear can also help to keep the paint underneath from lifting. A clear matte with "tooth" for the upper layer to adhere too.

Thanks Spencer!

First, yes, I have stripped it once and no, I didn't sand the primer before application. AAAAAGGGGGAAAGAH! Okay. Naive me, again, didn't know that the paints would be SOOOOOOO finicky about going down. I now have more respect for the awesome paint jobs I see here.

Second, No, I didn't de-tack the tape; learning alot here - didn't think I had to. Plus I didn't want paint leak so I made use to burnish the edges quite well.

Third, humidity is a factor here in Houston. I could bring the parts, once painted, in the house as the AC generally takes the humidity out of the air so that should help. That is a solution, along with the hair dryer, short of buying a dehumidifier chamber. ;)

Thanks for the clear coat tip. Hadn't thought of that!

Shawn! XD Thanks for the empathy!

Decoman, thanks for the opinion. Coupled with the advice I have gotten above, I think I will try "de-tacking" the tape. I assumed (there's that word again!) that, since Tamiya tape is used by professional Gundam modelers, that it would be exactly what is needed straight off the role. Looks like I was wrong.


All, thanks for your help and your replies! I will carry on (I REALLY want to see this one done!) and finish. Thanks again for helping me get the best possible result!

Very much appreciated.

Steve





"To be honest with you, Picard, a significant number of my crew members have expressed a desire to return even knowing the odds. Some because they can't bear to live without their loved ones, some because they don't like the idea of slipping out in the middle of a fight."

Offline RossW

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Re: Painting woes part duex
« Reply #7 on: March 11, 2019, 09:52:19 am »
In my experience, you should not need to detack Tamiya tape (household painter tape, perhaps). Detacking can also introduce fibres or lint or hair which can end up embedded in the paint. As always, YMMV.

But I think if the primer did not peel off then the issue is probably more to do with the Vallejo paints. I have found some paints adhere better than others (e.g. Tamiya, Mission Models) but probably the thickness of the application, humidity and time before masking are more important. Can you do some tests on spare parts before re-doing your model?

 




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