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paint problems - - - tamiya on airfix


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Started painting my 1/72 Grumman F4F-4.  And got surprised and disappointed.  Primed the outer wing panels with Tamiya white fine surface primer, and it was both blotchy and had poor coverage.  Drew away from any surface disturbance (panel lines, inspection panels) and blotchy spots of uneven coverage on the detail-free areas.  I got the tail surfaces and flaps painted - - - but the Tamiya rattle-can white covers terribly, drawing away from surface detail leaving gray lines showing through.  I am somehow doing something(s) wrong, but I have no idea what I'm messing up.  This is all new and disturbing country for me.  I do not remember these problems when using the very same rattle cans on other projects, none of them Airfix.  Something I need to do prior to trying to paint?  I'd washed the parts with naphtha and alcohol before painting and dried them with compressed air.  

 

Suggestions, ideas? 

 

And if frustrations overcome me, suggestions on stripping back to bare plastic, what's to do?  Alcohol immersion, brake fluid immersion?  

 

Thanks!

Edited by peter havriluk
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If the paint is pulling away from surface features, I wonder if the plastic had some surface contaminant? Some people will always wash the plastic before working with it. I sometime do that if it looks or feels like it's needed. But, I always give the ready-to-paint model a once over with 91% isopropyl alcohol using cosmetic cotton pads and cotton buds.

 

If you do need to strip the model, I've found Mr Thinner to be aggressive enough to remove the paint but not to damage the plastic. I just did this very task because some too-old Alcad went on all blotchy and rough.

Edited by dnl42
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Sorry to hear that, since it covers poorly, I think it may be too thin/not mixed up well. Have you shaken the can thoroughly? I ask because you didn't mentioned it. Depending on how long the can has been stored, not only at home but also in the shop, it can take a while to get it well mixed up. There are small steel balls in the can, you should then hear clearly when they hit the metal bottom of the can, instead of a thick layer of primer. I doubt it's the plastic, but just to make sure, you could try it on sprue runners or spare parts of other kits, to see if it cover well there. Or on a black cat :-) 

 

Otherwise it have to a bad can then I guess. But if it was indeed not well mixed up, then be careful, there may be too little thinner in the can now, even you get it well mixed up, the primer may be too thick now, that will create other problems.

 

I don't know how bad it looks, maybe after a few good layers it will still be OK. Isopropyl alcohol or rubbing alcohol is not very aggressive but it can certainly remove Tamiya lacquer primer, I tried with 99 point some thing % before, , it has no effect on plastic and clear plastic at all, at least no visible, the primer can be slowly but surely rubbed off. Immersion should work too but that will probably messed up the painting elsewhere like the cockpit.
 

Edited by delide
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Thanks, folks.  Good advice about the rattle cans.  I do shake vigorously prior to use, but reality doesn't respect opinions.  I think the easiest fix is to darken the hobby shop's door tomorrow and buy a new can of white paint and see what happens.  The one I'm fussing about is nearly empty, see advice above about end-of-can thickening, which I hadn't thought to be a problem. 

 

I've used this can of white 'fine' primer on a few projects already, but those cans hold about twice what the color cans do, and I think it's about half down.  And prior use didn't raise any alarms. And I'll test it on a known good surface before trying to paint airplane parts again.

 

Meanwhile all the parts that I'd painted (outer wing panels, empennage, flaps) are sitting in brake fluid for a while.  Enough circling the problem.  Back up to the beginning and restart.

 

I'll speak up when I'm done with the project as to how I got it done.  

 

Thanks, everybody.

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6 hours ago, Milo said:

One other thing about rattle cans, I soak them in hot water for 10 minutes or so.  That seems to make a difference with flow...

This.

 

Yeah, I often do this although I've never had any problems with Tamiya spray paints even when shooting them in normal room temp. 

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Parts in brake fluid for days, scrubbed off.  Air dried. Soap and hot water.  Air dried.  Alcohol wipedown.  Air dried.  New can of primer.  Same results.  Removed same before it dried.   I give up, on this particular model.  Humbrol acrylic primer worked just fine. Proud  owner of a mystery. 

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I’m a major fan of Tamiya spray and have transitioned to using their various silver colors for bare metal. No more so-called metal products for me! BUT, one thing I think effects how they spray is temperature. I experienced a curdling effect last winter when I was spraying outside in temepratures around 40 degrees. The can specifies spraying in warmer temperatures; can’t remember the range but was above 60 If I remember. I also lay on a misty coat first followed by heavier shiny coats. Heavy early coats have resulted in a “bird’s eye” effect. 

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Bill, I think we're singing out of the same hymnbook.  Temperature in the shop was measured at 69 degrees F.  I got what you called a 'bird's eye' effect on the first application past the mist coat.  Seeing as I got the effect from both cans of primer, one shiny new and the first one half down, this seems to be a feature.  Surprising to me is that I'd not experienced it before.  What also surprised me was what I saw a change in behavior, for the worse, as I'd painted the cowling and auxiliary fuel tanks with the same materials and had no problems,  days before I got surprised with the flying surfaces.  I had been very pleased how the Tamiya paints and primers had fine atomization and covered well.  Learn something every day.  And the Humbrol spray acrylic primer covered and behaved just as I'd experienced with Tamiya's primers. 

 

Thanks!

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