Tamiya Primer Problem

Tools, Techniques, and Reference Materials Painting and airbrushing
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(I originally posted this question in the Intro section and got some excellent thoughts, but a couple of folks suggested I post it in the Painting section and see if anyone had any further ideas.)

New to the forum, but I have been building plastic models 4ever. Mostly SF vehicles, some cars. Call me an “Old Newbie?” Although I’ve been at the hobby pretty much my whole life, I am continually frustrated in my attempts to improve my paint jobs. If I get a decent one, and use the same techniques or materials again, the next time it comes out crummy. So I am definitely missing something.

Today, I used Tamiya Fine White Primer on a car body, and on certain portions of the body it looks like sandpaper, I mean really rough. I’ve used the same primer before with good results, but I’ve also wrecked a couple of models by getting that super-rough finish, and trying to remove it with paint cleaner. (I won’t do that again, believe me!)

So what makes for an extremely rough primer coat? Not enough layers? Too many layers? High humidity? Bad mojo? I painted it outside, warm day, new can of primer, body was carefully washed beforehand. I think the humidity was high, though. I did several light coats, and I figure something is up because the finish is extremely uneven, some areas being almost good, and others being awful.

(Since this post, I was able to sand the finish to something reasonably smooth. The roughest spots were very easy to sand - almost chalk-like.)

I bet this is an extremely common problem, that you guys figured out a million years ago, but if any of you would be so kind as to enlighten a very old newbie what I am doing wrong, it would be greatly appreciated. Pix below, but beware - they are grizzly!

2

Wow that looks like my ceiling. Sorry I have no clue but will be checking to see what the more experienced have to say.

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Was there much wind when you were applying the primer? Its hard to really see good detail in the photos, but it sort of looks like an extreme version of orange peel, where the paint is practically dry when it hits the surface of the model. Any wind at all can cause that. Or it could just be that the nozzle is spitting. Have you tried holding the can upside down and spraying briefly to clear the nozzle? Something I have done to permanently remove the environmental and mechanical variables of using a rattle can is to not use them at all. I decant all of my rattle cans into 4 ounce mason jars so I can airbrush them instead. I just took one of the mason jar lids, drilled a hole in it, and then installed a 1/4" ID rubber gromet to use when decanting. I then take a party straw and epoxy that to the rattle can nozzle. Once that cures, you can decant an entire 3 ounce rattle can into that jar and use tiny bits at a time for airbrushing. I used to have the same problems you’re having with all kinds of primers and paints in rattle cans, having to paint outside. Since adopting the decanting method, I have not had a single issue, and the models look better with the vastly thinner primer and paint on them…the details pop. The Tamiya Surface Primers have a great nozzle and lay down paint better than most rattle cans, but its still too thick for my liking now that I’ve seen the results of decanting and airbrushing.

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I also suspect the paint is drying midair.

I don’t use much spray can anymore, but Tamiya rattle can primer is about the most forgiving rattle can model paint out there. Since you mentioned you have trouble painting, it could be techique.

In a nutshell, press the nozzle and start your sweep off the model. Use a smooth steady motion and never stop, continuing off the model before you release the nozzle. Repeat on the next pass, overlapping at whatever works with the previous one. That’s really all there is too it. If it is rough, you are too far away. If the coverage is too light, you are sweeping too fast. If it pools or turns ‘glossy’, you are going to slow or you paused.

Eagle already hit on the other variables, wind, temp and humidity. I’ve sprayed tamiya outside in some pretty unforgiving conditions and can’t say I’ve ever had a problem.

If this is too basic, I mean no harm. Since you stated painting is troublesome, I just figured why not make sure the basics are covered.

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I thought I answered this already. It went on too dry, probably from too great a distance in warm conditions… Sorry if everyone already stated that or if somehow I double posted.

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yes, you did mention this previously, and I did appreciate it!

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Yes indeed, there was a decent breeze going, and although I tried to wait until the breeze died down, it was not “still” by any means. Plus, it was 90 and high humidity. And I think I was too far away. Thanks for clarifying all this. I like the idea of decanting and airbrushing the rest - that way I don’t waste the rest of the paint. Many thanks!

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I appreciate all input, and none is too basic! It seems that no matter how old I get, there are still basic things which need to be relearned all the time. I have much to learn with painting, that is for sure! I feel like I am still idling in my adolescent modeling mode, even today. I am certain that hanging around the FSM forums will help that considerably…

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If you decide to go the decanting route, a few things to remember from mistakes I made when first trying it:

  1. Make sure to shake the rattle can to thoroughly mix the paint before decanting it. If you don’t do that, the pigment that settled to the bottom of the can will be trapped in the can forever.

  2. Be very careful about stirring freshly-decanted paint. Stir it slowly, by hand, and don’t use a motorized paint stirrer if you have one. I used my motorized stirrer the first time and the paint immediately frothed up and went all over my cutting mat due to the propellant gas that takes a while to come out of solution.

  3. Don’t put the mason jar lid on tightly. Just put it on and give it a couple of turns. It will need about 2 hours to off-gas to where its safe to tightly screw on the lid. Haven’t had a jar explode yet, but it is a possibility while its off-gassing.

After you have had your jars of decanted paint for a few days, it will be safe to use a motorized stirrer without causing the paint to froth. The Tamiya primers, on the other hand, you should always stir by hand. There is a component in their primers that settles to the bottom and turns into a gel. That’s normal, so don’t worry that your primer is ruined. It just has to be stirred slowly and carefully to get everything back together without a glob of gel getting stuck on your motorized stirrer and flinging primer everywhere.

Heh…as you can see…I’ve made pretty much every mistake you can make when decanting, so all my advice is more of a “Don’t be like me!”.

:smiley:

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I can’t tell you how much I appreciate this advice. This will be my first decanting for airbrushing purposes, and I’m sure I would not have thought of any of these things, and made a big fat mess as usual. I’m printing out your directions and following them to the letter. My only experience in decanting is capturing a little bit of a spray color into a bottle for detail and touch-up work. Many Thanks!

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You’re very welcome! It was a painful learning experience, so its good to be able to help someone else avoid that pain. LOL

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This problem exist in airbrush also. But what I found is like what everybody was saying, it dries up on the way to your model. Just to share, I have been using a 0.3 airbrush for everything. And priming is the frustrating part for me. The airbrush atomized the paint so well that it dries up on its way to my model. Resulting in a gritty finish. I read somewhere that you need to spray a larger volume of paint so it wont dry up. Fortunately, I have a 0.5 airbrush that I was so scared to use last time. And when I use that for priming. The result was night and day! Its so smooth that it really change my perception for bigger needle airbrush. It put down a lot of paint without running and the result are just stellar. And I am trying to get the Iwata RG3L with 1.0 needle so I can finish my Deagostini falcon.